WO2005001420A2 - Method and apparatus for sensing hydrogen gas - Google Patents

Method and apparatus for sensing hydrogen gas Download PDF

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Publication number
WO2005001420A2
WO2005001420A2 PCT/US2004/017324 US2004017324W WO2005001420A2 WO 2005001420 A2 WO2005001420 A2 WO 2005001420A2 US 2004017324 W US2004017324 W US 2004017324W WO 2005001420 A2 WO2005001420 A2 WO 2005001420A2
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WO
WIPO (PCT)
Prior art keywords
hydrogen
layer
top surface
substrate
nanoparticle
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Application number
PCT/US2004/017324
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French (fr)
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WO2005001420A3 (en
Inventor
Kwok Ng
Greg Monty
Yunjun Li
Zvi Yaniv
Prabhu Soundarrajan
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Nano-Proprietary, Inc.
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Application filed by Nano-Proprietary, Inc. filed Critical Nano-Proprietary, Inc.
Priority to EP04754029A priority Critical patent/EP1629259A4/en
Priority to CA002523583A priority patent/CA2523583A1/en
Priority to JP2006515084A priority patent/JP4629665B2/en
Priority to KR1020057022671A priority patent/KR101110532B1/en
Publication of WO2005001420A2 publication Critical patent/WO2005001420A2/en
Publication of WO2005001420A3 publication Critical patent/WO2005001420A3/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
    • G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
    • G01N33/005—H2
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y15/00—Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G01N27/125—Composition of the body, e.g. the composition of its sensitive layer
    • G01N27/127—Composition of the body, e.g. the composition of its sensitive layer comprising nanoparticles

Definitions

  • the present invention relates to hydrogen gas sensors and, more particularly, to hydrogen gas sensors and switches that utilize metal nanowires.
  • Hydrogen is now used in the transportation, petrochemical, food processing, microchip, and spacecraft industries. Each of these industries needs reliable hydrogen sensors for many applications, for example, pinpointing leaks to prevent the possibility of explosions in production equipment, transport tanks, and storage tanks. Advances in fuel cell technology will provide numerous future applications for hydrogen sensors. Hydrogen sensors, in some instances, could be used to warn of an imminent equipment failure.
  • Hydrogen sensor packages are also needed to monitor hydrogen concentration in the feed gas to fuel cells for process control. Hydrogen sensor packages in fuel cells require high sensitivity. Such sensor packages should have a wide measurement range spanning from below 1% up to 100% hydrogen. The measurement range is dependent on which fuel cell technology is used and the status of the fuel cell. Detectors are needed also to monitor for leaks in the delivery system. For transportation and other portable applications, hydrogen detectors operating in ambient air are needed to ensure the safety of hydrogen/air mixtures and to detect hydrogen leaks before they become a hazard. At high hydrogen concentration levels, issues associated with the potentially deteriorating effect on the oxygen pump operation must be addressed. Finally, hydrogen sensors must be highly selective in monitoring hydrogen in ambient air.
  • the alpha-to-beta phase transition in the nanowire material is the mechanism for operation of these sensors. There is first a chemical absorption of hydrogen by the palladium nanocrystals of the nanowire. This causes expansion of the lattice by as much as 5-10%, causing the palladium nanocrystals that were initially isolated from each other to touch and form an excellent low-resistance wire.
  • Favier et al. A lack of complete characterization of the palladium nanowires has limited the understanding of those devices.
  • the Favier et al. method and apparatus utilizes nanowires that are electrochemically prepared by electrodepositon onto a stepped, conductive surface such as graphite.
  • the present invention is directed to an improved method and apparatus for sensing hydrogen gas.
  • An embodiment comprises the steps of depositing an insulating layer onto a silicon substrate, depositing a metal layer on the top surface of the insulating layer, and depositing a plurality of nanoparticles onto the side- wall of the metal layer.
  • the metal layer may be removed.
  • Another embodiment of the present invention is directed to a hydrogen sensing apparatus comprising nanoparticles deposited on a substrate to form one or more nanoparticle paths which conduct electricity in the presence of hydrogen and wherein the nanoparticles were formed in close proximity to the substrate and not transferred off of a conductive substrate.
  • Another embodiment of the present invention is directed to a method of sensing hydrogen including depositing a first layer of material onto a second layer of material, depositing a metal layer on the second layer of material, depositing a third layer of material on the metal layer, removing a portion of the metal layer to expose one or more side- walls of the metal layer, depositing nanoparticles on the side-walls of the metal layer, and sensing a change of resistivity of the nanoparticles when they are exposed to hydrogen.
  • An embodiment of the present invention is directed to a palladium-silver alloy nanowire technology that eliminates the (1) unpredictable formation of palladium nanowires; (2) narrow temperature range of operation; and (3) narrow range of sensitivity to hydrogen concentration.
  • a basis of the present invention is the ability to co-deposit palladium and palladium-silver alloy nanoparticles or nanowires electiOchemically on a patterned surface without the need for a transfer process.
  • the present invention operates by measuring the resistance of many metal nanowires arrayed in parallel in the presence of hydrogen gas.
  • the present invention may also operate by, in the presence of hydrogen, measuring the resistance of nanowires deposited as a film.
  • the nanowires or nanofilm contain gaps that function as open switches in the absence of hydrogen. In the presence of hydrogen, the gaps close and behave like closed switches. Therefore, the resistance across an arcay of palladium or palladium alloy nanowires or nanofilm is high in the absence of hydrogen and low in the presence of hydrogen.
  • the nanowires or nanofilm are typically composed of palladium and its alloys.
  • any other metal or metal alloy having a stable metal hydride phase such as copper, gold, nickel, platinum and the like may also be used.
  • path is meant to encompass nanowires, nanofilm, and/or any potentially electrically conductive path.
  • nanowires were electrochemically prepared by electrodepositon onto a stepped surface such as graphite. The nanowires were then transferred off of the graphite onto a polystyrene or cyanoacrylate film. The transfer process contributed to a decrease in sensitivity and operating range for hydrogen sensors. It is an object of the present invention to increase sensitivity and operating range of the hydrogen sensors by dispensing with the need to transfer nanowires during fabrication.
  • FIGURE 1 is an image from a scanning electron microscope (SEM) of a nanoparticle thin film
  • FIGURE 2 is an SEM image of 300 nm palladium nanowires prepared by side-wall-electroplating technique
  • FIGURE 3 is a graph of hydrogen sensor responses at varying hydrogen concentrations at 70°C
  • FIGURE 4 is a graph of hydrogen sensor responses at varying hydrogen concentrations at 70°C
  • FIGURE 5a is a schematic representation of one embodiment of the present invention
  • FIGURE 5b is a graph of hydrogen sensor responses at 100°C with hydrogen concentrations of 0.5%
  • FIGURE 5c is a graph of hydrogen sensor responses during 5 cycles of testing at 1% hydrogen concentration at 120°C
  • FIGURE 6a is a schematic representation of one embodiment of the present invention
  • FIGURE 6b is a graph of responses for the hydrogen sensor from FIGURE 6a at room temperature at varying levels of hydrogen as shown
  • FIGURE 6c is a graph of responses for the hydrogen sensor from FIGURE 6a at 70°C at varying levels of hydrogen as shown
  • FIGURE 6d is a graph of responses for the hydrogen sensor from FIGURE 6a at room temperature at varying levels of hydrogen as shown
  • FIGURE 7a is a schematic representation of another embodiment of the present invention
  • FIGURE 7b is a graph of responses for the hydrogen sensor from FIGURE 7a at room temperature at varying levels of hydrogen as shown
  • FIGURE 7c is a graph of responses for the hydrogen sensor from FIGURE 7a at 120° at varying levels of hydrogen as shown
  • FIGURE 8a is a schematic representation of an early stage of fabrication of an embodiment of the present invention
  • FIGURE 8b is
  • the incorporation of silver with palladium also addresses the issue of sensitivity of the nanowires to different levels of hydrogen concentrations.
  • Pure palladium nanowires typically do not provide enough sensitivity to allow detection over a large range of hydrogen concentrations. At room temperature, pure palladium nanowires are able to detect a concentration of about 2% hydrogen. At higher temperatures, pure palladium wires require a higher concentration of hydrogen for detection.
  • the incorporation of silver in palladium nanowires provides a greater range of detection suitable to make hydrogen sensors.
  • the substrate for an embodiment can be any insulating surface such as polymer, glass, silicon, or silicon nitride. A thin layer of titanium is deposited onto the substrate to fonn a conductive area for electroplating.
  • a photoresist pattern is prepared on the top of the substrate by lithography. Palladium or palladium-silver alloy nanoparticles/nanowires are then electroplated on the exposed titanium surface.
  • the palladium electroplating bath contains 1 mM PdCl 2 , 0.1 M HCl in water.
  • the palladium-silver electroplating bath contains 0.8 mM PdCl 2 , 0.2 mM AgN0 3 , 0.1 M HCl, 0.1 M NaN0 3 , and 2 M NaCl in deionized water.
  • FIGURE 1 shows an image of a nanoparticle thin film that consists of nanoparticles with a 100 nm diameter.
  • FIGURE 2 shows an image of 300 nm palladium nanowires prepared by side wall technique.
  • FIGURE 3 and FIGURE 4 show the response of a palladium-silver alloy hydrogen sensor at 70°C for varying hydrogen concentrations over time. Note that the devices are essentially OFF when no hydrogen is present and palladium alloy-nanocrystals in the device act as an "open circuit" with very-high resistance.
  • the palladium alloy-nanocrystals in the device touch each other through expansion of the lattice. This causes any nanogaps in the wires to close (ON state) and the nanowires behave as a "short circuit" with very-low resistance.
  • the sensors have a highly desirable characteristic in that the sensors require essentially zero power in the absence of hydrogen. The sensor acts like an open circuit in the absence of hydrogen and only draws a small amount of power when an alarm condition occurs. This is the ideal situation for a good hydrogen detector: OFF in the absence of hydrogen, and ON only when hydrogen is present.
  • FIGURE 5 a a particular embodiment of making a hydrogen sensor involves evaporating a
  • a photoresist (not shown) is patterned on the titanium layer 302 in a well-known manner.
  • a layer 304 of nanoparticles of palladium-silver alloy are then electroplated onto the surface.
  • the device is heated to 500°C for 2 hours in air to oxidize the titanium layer.
  • FIGURE 5b displays test results for this embodiment at 100°C.
  • an exemplary sensor of the instant embodiment was tested for 3 cycles with hydrogen concentrations of 0.5%, 1.5%, and 2%.
  • FIGURE 5c displays results for tests at 120°C with 1% hydrogen concentrations.
  • FIGURE 5c illustrates that the sensor did not degrade after 5 cycling tests.
  • FIGURE 6a Another embodiment of the present invention is depicted schematically in FIGURE 6a.
  • a 5000 A layer 602 of SiNx is deposited on a silicon substrate 600.
  • a layer 604 of 1000 A thick titanium is then deposited on layer 602.
  • lithography a pattern (not shown) is created on the substrate.
  • a thin film 606 of palladium-silver nanoparticles is electroplated to layer 604.
  • the palladium-silver alloy was electroplated at 300 ⁇ A for 1 second and 20 ⁇ A for 600 seconds.
  • oxidizing the titanium 604 forms Ti ⁇ 2- In one example, the titanium was exposed to 500°C air overnight.
  • FIGURES 6b-6d illustrate results achieved by testing the exemplary embodiment as depicted in
  • FIGURE 6a illustrates test results performed at room temperature.
  • the device was first tested at room temperature with hydrogen concentrations ranging from 0.5% to 4%.
  • the voltage applied was 0.1V.
  • the current was about 3E-6A with no hydrogen present.
  • the current rose to 7E-6A at 0.5% hydrogen and 1E-5A at 1% hydrogen.
  • the response was slowly saturated at around 3% hydrogen concentration with a current of 1.2E- 5 A, about 400% of the current at OFF state.
  • FIGURE 6c illustrates test results performed at 70°C for the exemplary embodiment as depicted in
  • FIGURE 6a At 120°C, the sensor did not respond to hydrogen.
  • the results shown in FIGURE 6c were achieved after slowly reducing the temperature from 120°C to 70°C.
  • FIGURE 6c illustrates that the sensor was essentially non-operational when the temperature was raised to 120°C, but the sensor regained its operation when the temperature was reduced to 70°C.
  • FIGURE 6d illustrates test results for the embodiment depicted in FIGURE 6a after cooling the device from 70°C to room temperature.
  • the device responded to hydrogen with similar magnitude as the previous test at room temperature, illustrated in FIGURE 6b.
  • the OFF state the device had a current of about 1.5E-6A.
  • the current was about 7E-6A at 4% hydrogen.
  • FIGURE 7a shows a silicon substrate 700 deposited with 5000 A of SiNx, forming layer 702. Next, 200 A of titanium is deposited to form layer 704.
  • a layer 706 of palladium-silver is electroplated to titanium layer 704.
  • palladium-silver was electroplated at 300 ⁇ A for 1 second and 20 ⁇ A for 600 seconds.
  • Test results of an example of the instant embodiment are illustrated in FIGURE 7b. The results in FIGURE 7b were achieved at room temperature.
  • FIGURES 8a-8e Another embodiment of the present invention is depicted schematically in FIGURES 8a-8e.
  • Si0 2 is deposited on a silicon substrate 800 to form a 5000 A layer 802 of Si0 2 .
  • SiNx or other suitable materials may be substituted for Si0 2 .
  • Titanium 200 A thick is deposited to form layer 804.
  • the photoresist 806 is deposited on the substrate and patterned by photolithography leaving the assembly substantially as depicted in FIGURE 8b, with layer 804 having two side- walls.
  • Nanowires 808 made from palladium-silver alloys are then electroplated onto the side-walls of the titanium 804.
  • palladium-silver was electroplated using a side-wall plating technique at 300 ⁇ A for 1 second and 20 ⁇ A for 600 seconds. Since the sidewall of the metal is the only place exposed to the electrolytic bath, the palladium-silver will be deposited on the sidewall only and form the nanowires at the edge of the metal lines.
  • the remaining titanium 804 is etched away, leaving the assembly as shown in FIGURE 8c.
  • the titanium 804 could be oxidized at high temperature or left on the substrate.
  • the sensor is functional witliout removing the metal layer, but has a low S N ratio. The removal of the metal layer provides higher S/N ratio.
  • the substrate can be used as a working electrode in a three- electrode plating system with a saturated calomel electrode (SCE) as the reference electrode and platinum wire as the counter electrode.
  • SCE saturated calomel electrode
  • the three electrodes can be immersed in a palladium silver alloy plating solution bath solution consisting of 2.5 mM of PdC12, 0.5 mM of Ag ⁇ 0 3 , 0.05 M of NaN0 3 , 0.05 M of HCl, and 2 M (20g in lOOmL) of NaCl in water.
  • a standard electrochemical program, namely chronopotentiometry can be used for this process.
  • the electrochemical plating conditions can be as follows: using a pure palladium plating bath, apply -300 ⁇ A for 10 sec, then apply -20 ⁇ A for 450sec. After electroplating, the substrate can be immersed in acetone, followed by IPA and water to remove the photoresist on the surface.
  • the side-wall plating technique for an embodiment as shown in Figure 8(c) and operational at room temperature can be accomplished as follows: the substrate can be used as a working electrode in a three- electrode plating system with a saturated calomel electrode (SCE) as the reference electrode and platinum wire as the counter electrode.
  • SCE saturated calomel electrode
  • the three electrodes can be immersed in a pure palladium plating bath consisting of 1 mM of PdCl 2 and 0.1 M HCl in water.
  • a standard electrochemical program namely chronopotentiometry can be used for this process.
  • the electrochemical plating conditions can be as follows: using pure palladium plating bath, apply -300 ⁇ A for 10 sec, then apply -20 ⁇ A for 450sec. After electroplating, the substrate can be immersed in acetone, followed by IPA and water to remove the photoresist on the surface.
  • FIGURE 8d depicts an embodiment created by patterning the substrate using photolithography to electroplate multiple nanowires 808 to the side- walls of titanium strips 804.
  • FIGURE 8(d) is made in the similar fashion as outlined in 8(a) to 8(c); however, FIGURE 8(d) shows multiple nanowires arranged in an array.
  • a hydrogen sensor is utilized by connecting conductors to the ends of the array of nanowires which electrically connects the nanowires in parallel.
  • silver paste is applied to the ends of the array of nanowires and separate wires are connected to the silver paste on each end.
  • a voltage is then applied across the parallel nanowires, and the resultant current is measured to determine whether there is hydrogen present.
  • the particular embodiment as described in Figure 8d can be fabricated as follows: 5000 A Si0 2 , item 802, is deposited on a 4 inch silicon wafer, item 800, using a E-beam evaporator followed by a layer of 200 A titanium, item 804. The substrate is then coated with a photoresist hexamethylenedisilane (HMDS) for 30 seconds at 700 RPM followed by a positive photoresist for 90 seconds at 3000 RPM. The substrate is then exposed under UV light with a homemade H-Sensor 5mm line mask (not shown) for 25 sec and further developed by photoresist developer diluted for 40 seconds.
  • HMDS photoresist hexamethylenedisilane
  • the substrate is then rinsed with water for 30 minutes, dried using a blow drier, and heated in an oven for 10 minutes at 120°C.
  • the titanium layer not covered by the photo resist is then etched away by a titanium etchant, exposing the sidewall of the titanium layer over the entire substrate.
  • the pattern is exposed under UV with homemade mask (not shown) for 25 seconds after proper alignment of the sensor pattern.
  • the substrate is then developed by 400 K developer diluted for 40 seconds.
  • the substrate is then rinsed with water for 30 minutes, dried using a blow drier, and heated in an oven for 10 minutes at 120°C.
  • the sidewall plating technique is then used to electroplate the nanoparticles 808 onto the substrate.
  • FIGURE 8e shows the results from testing an example of the embodiment as depicted in FIGURE 8c.
  • the test began at room temperature. The temperature was increased to 103°C, then 136°C, and then 178°C. As the temperature increased, the current increased due to the larger thermal expansion coefficient of palladium- silver compared to SiNx. The palladium-silver nanowires 808 expanded faster than the substrate and the resistance lowered. With the test chamber at 103°C, the sensor was tested with hydrogen concentrations of 0.25%), 1.0%, and 4.0%).
  • FIGURE 9a - 9b depicts another embodiment of the present invention.
  • the embodiment of FIGURE 9a - 9b produces response curves typical of other embodiments described herein, but the embodiment in FIGURE 9a - 9b is suitable for fabricating hydrogen sensors to be operable both in ambient air and under oil, such as transformer oil.
  • the embodiment of FIGURE 9a - 9b can be fabricated using photolithography as follows: First, a 5000 A layer 912 of silicon nitride is deposited on a 4 inch silicon wafer 900 using a E-beam evaporator followed by a layer 902 of 200°A titanium.
  • the substrate is then coated with a photoresist hexamethylenedisilane (HMDS) for 30 seconds at 700 RPM followed by a positive photoresist for 90 seconds at 3000 RPM.
  • HMDS photoresist hexamethylenedisilane
  • the substrate is then exposed under UV light with homemade H-Sensor 5mm line mask (not shown) for 25 sec and further developed by photoresist developer diluted for 40 seconds.
  • the substrate is then rinsed with water for 30 minutes, dried using a blow drier, and heated in an oven for 10 minutes at 120°C.
  • a layer 904 of 100 A chromium and 300 A gold, item 906, is deposited using E-Beam.
  • the resistance of the substrate can be measured to be less than 10 ohms.
  • the photoresist is lifted off using appropriate stripper followed by heating in oven for 30 minutes at 90°C and subsequent drying.
  • the substrate is then coated with a photo resist 908 for 30 seconds at 700 RPM followed by positive photoresist for 90 seconds at 3000 RPM.
  • the pattern is exposed under UV with homemade mask (not shown) for 25 seconds after proper alignment of the sensor pattern.
  • the substrate is then developed by photoresist developer diluted for 40 seconds.
  • the substrate is then rinsed with water for 30 min, dried using a blow drier, and heated in an oven for 10 minutes at 120°C.
  • a plating technique is then used to electroplate the nanoparticles 910 onto the substrate. Note, in an embodiment the sidewall plating technique is not used because the titanium is not etched in this process.
  • FIGURES 10a- lOd show various applications for the present invention.
  • FIGURE 10a depicts an application for utilizing hydrogen sensors to monitor hydrogen levels inside a vehicle and within a fuel cell. Sensors in the vehicle cabin monitor to ensure that dangerous concentrations of hydrogen do not create an unsafe condition for drivers and passengers. Sensors within the fuel cell ensure proper operation and health of the fuel cell.
  • FIGURE 10b represents a fuel cell used to monitor the health of the fuel cell. The hydrogen sensor is placed to ensure proper hydrogen levels in the intake and to monitor the hydrogen level in the exhaust.
  • FIGURE lOd depicts an application for monitoring hydrogen concentration in and around a home utilizing a fuel cell.
  • FIGURE lOc depicts yet another application for hydrogen sensors in power equipment.
  • power transformers and switchmg equipment are often filled with insulating oil. A breakdown or contamination of the insulating oil can cause short circuits and lead to dangerous explosions and fires. Some potential failures are predicted by monitoring for buildups of hydrogen and other gases in the transformer oil.
  • FIGURE 10c shows a hydrogen sensor placed under the insulating oil of a transformer. Another sensor could be placed above the oil to monitor hydrogen levels.
  • hydrogen sensors may also be placed in any application where a buildup of hydrogen signals a dangerous condition.
  • the present invention relates to using palladium-silver alloy thin film (or array, network) and nano/meso wires as an active element for hydrogen sensing applications.
  • Embodiments of the present invention can detect 0.25% hydrogen in nitrogen.
  • metal for example, titanium
  • oxidizing a titanium layer to Ti0 2 and preparing conductive palladium or palladium-silver nanostructures on the less conductive titanium or Ti0 2 surface, there is no need for the transfer process which caused degradation of the sensor at high temperature.

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Abstract

A hydrogen sensor and/or switch fabricated from an array of nanowires or a nanoparticle thick film composed of metal or metal alloys. The sensor and/or switch demonstrates a wide operating temperature range and shortened response time due to fabrication materials and methods. The nanowires or nanoparticle thick films demonstrate an increase in conductivity in the presence of hydrogen.

Description

METHOD AND APPARATUS FOR SENSING HYDROGEN GAS CROSS-REFERENCE TO RELATED APPLICATIONS The present invention claims priority to U.S. Provisional Application Serial No. 60/475,558. TECHNICAL FIELD The present invention relates to hydrogen gas sensors and, more particularly, to hydrogen gas sensors and switches that utilize metal nanowires.
BACKGROUND INFORMATION Like any fuel, hydrogen stores large amounts of energy, and handling hydrogen requires safety precautions. As the use of hydrogen fuel becomes more common, there will be an increased need for reliable hydrogen sensors. Hydrogen is now used in the transportation, petrochemical, food processing, microchip, and spacecraft industries. Each of these industries needs reliable hydrogen sensors for many applications, for example, pinpointing leaks to prevent the possibility of explosions in production equipment, transport tanks, and storage tanks. Advances in fuel cell technology will provide numerous future applications for hydrogen sensors. Hydrogen sensors, in some instances, could be used to warn of an imminent equipment failure.
Electrical transformers and other electrical equipment are often filled with insulating oil to provide electrical insulation between energized parts. The presence of hydrogen in the insulating oil can indicate a failure or potential explosion. Hydrogen sensors could be utilized both under the insulating oil and in the air immediately above the insulating oil. Therefore, closely monitoring hydrogen levels in and around equipment containing insulating oil could be an effective tool in predicting and preventing equipment failure. As fuel cell technology advances, fuel cells will see greater use as power sources for both vehicles and homes. Since hydrogen can be a highly explosive gas, each fuel cell system needs hydrogen detectors to sense and alarm in the event of a hydrogen leak. Hydrogen detectors can also be placed inside a fuel cell to monitor the health of the fuel cell. Hydrogen sensor packages are also needed to monitor hydrogen concentration in the feed gas to fuel cells for process control. Hydrogen sensor packages in fuel cells require high sensitivity. Such sensor packages should have a wide measurement range spanning from below 1% up to 100% hydrogen. The measurement range is dependent on which fuel cell technology is used and the status of the fuel cell. Detectors are needed also to monitor for leaks in the delivery system. For transportation and other portable applications, hydrogen detectors operating in ambient air are needed to ensure the safety of hydrogen/air mixtures and to detect hydrogen leaks before they become a hazard. At high hydrogen concentration levels, issues associated with the potentially deteriorating effect on the oxygen pump operation must be addressed. Finally, hydrogen sensors must be highly selective in monitoring hydrogen in ambient air. There are many commercially available hydrogen sensors, however, most of them are either very expensive or do not have a wide operating temperature range. Additionally, most sensors sold today have heaters included with the sensor to maintain elevated operating temperatures, requiring high power consumption that is undesirable for portable applications. Favier et al. pioneered the use of palladium nanowires in 2001 by producing a demonstration hydrogen detector. The disclosure of Favier et al. can be read in an article published in Science, Vol. 293, September 21, 2001. Hydrogen sensors prepared by this method have incredible properties due to the nature of the chemical/mechanical/electrical characteristics of the nanotechnology of palladium nanowires. The hydrogen sensors operate by measuring the conductivity of metal nanowires arrayed in parallel. In the presence of hydrogen gas, the conductivity of the metal nanowires increases. The alpha-to-beta phase transition in the nanowire material is the mechanism for operation of these sensors. There is first a chemical absorption of hydrogen by the palladium nanocrystals of the nanowire. This causes expansion of the lattice by as much as 5-10%, causing the palladium nanocrystals that were initially isolated from each other to touch and form an excellent low-resistance wire. However, there are many drawbacks to systems as produced and disclosed by Favier et al. A lack of complete characterization of the palladium nanowires has limited the understanding of those devices. Also, the Favier et al. method and apparatus utilizes nanowires that are electrochemically prepared by electrodepositon onto a stepped, conductive surface such as graphite. This presents a problem because nanowires prepared on conductive surfaces are required to be transferred off of the conductive surface so that the conductivity of the nanowire array can be measured more readily. Such transfers of nanowires cause degradation of hydrogen sensing at higher temperatures. In summary, the major issues with pure palladium nanowires prepared on step edges of graphite are: (1) unpredictable formation of palladium nanowires; (2) narrow temperature range of operation; and (3) narrow range of sensitivity to hydrogen concentration. As a result, there is a need in the art for an apparatus and method for (1) predictably forming palladium and palladium alloy nanowires; (2) increasing the temperature operating range of sensors; and (3) increasing the range of hydrogen concentrations that can be measured.
SUMMARY OF THE INVENTION The present invention is directed to an improved method and apparatus for sensing hydrogen gas. An embodiment comprises the steps of depositing an insulating layer onto a silicon substrate, depositing a metal layer on the top surface of the insulating layer, and depositing a plurality of nanoparticles onto the side- wall of the metal layer. In an embodiment, the metal layer may be removed. Another embodiment of the present invention is directed to a hydrogen sensing apparatus comprising nanoparticles deposited on a substrate to form one or more nanoparticle paths which conduct electricity in the presence of hydrogen and wherein the nanoparticles were formed in close proximity to the substrate and not transferred off of a conductive substrate. Another embodiment of the present invention is directed to a method of sensing hydrogen including depositing a first layer of material onto a second layer of material, depositing a metal layer on the second layer of material, depositing a third layer of material on the metal layer, removing a portion of the metal layer to expose one or more side- walls of the metal layer, depositing nanoparticles on the side-walls of the metal layer, and sensing a change of resistivity of the nanoparticles when they are exposed to hydrogen. An embodiment of the present invention is directed to a palladium-silver alloy nanowire technology that eliminates the (1) unpredictable formation of palladium nanowires; (2) narrow temperature range of operation; and (3) narrow range of sensitivity to hydrogen concentration. A basis of the present invention is the ability to co-deposit palladium and palladium-silver alloy nanoparticles or nanowires electiOchemically on a patterned surface without the need for a transfer process. The present invention operates by measuring the resistance of many metal nanowires arrayed in parallel in the presence of hydrogen gas. The present invention may also operate by, in the presence of hydrogen, measuring the resistance of nanowires deposited as a film. The nanowires or nanofilm contain gaps that function as open switches in the absence of hydrogen. In the presence of hydrogen, the gaps close and behave like closed switches. Therefore, the resistance across an arcay of palladium or palladium alloy nanowires or nanofilm is high in the absence of hydrogen and low in the presence of hydrogen. The nanowires or nanofilm are typically composed of palladium and its alloys. One of ordinary skill recognizes that any other metal or metal alloy having a stable metal hydride phase such as copper, gold, nickel, platinum and the like may also be used. Herein the use of the term "path" is meant to encompass nanowires, nanofilm, and/or any potentially electrically conductive path. In the prior art, nanowires were electrochemically prepared by electrodepositon onto a stepped surface such as graphite. The nanowires were then transferred off of the graphite onto a polystyrene or cyanoacrylate film. The transfer process contributed to a decrease in sensitivity and operating range for hydrogen sensors. It is an object of the present invention to increase sensitivity and operating range of the hydrogen sensors by dispensing with the need to transfer nanowires during fabrication.
BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: FIGURE 1 is an image from a scanning electron microscope (SEM) of a nanoparticle thin film; FIGURE 2 is an SEM image of 300 nm palladium nanowires prepared by side-wall-electroplating technique; FIGURE 3 is a graph of hydrogen sensor responses at varying hydrogen concentrations at 70°C; FIGURE 4 is a graph of hydrogen sensor responses at varying hydrogen concentrations at 70°C; FIGURE 5a is a schematic representation of one embodiment of the present invention; FIGURE 5b is a graph of hydrogen sensor responses at 100°C with hydrogen concentrations of 0.5%,
1.5%, and 2%; FIGURE 5c is a graph of hydrogen sensor responses during 5 cycles of testing at 1% hydrogen concentration at 120°C; FIGURE 6a is a schematic representation of one embodiment of the present invention; FIGURE 6b is a graph of responses for the hydrogen sensor from FIGURE 6a at room temperature at varying levels of hydrogen as shown; FIGURE 6c is a graph of responses for the hydrogen sensor from FIGURE 6a at 70°C at varying levels of hydrogen as shown; FIGURE 6d is a graph of responses for the hydrogen sensor from FIGURE 6a at room temperature at varying levels of hydrogen as shown; FIGURE 7a is a schematic representation of another embodiment of the present invention; FIGURE 7b is a graph of responses for the hydrogen sensor from FIGURE 7a at room temperature at varying levels of hydrogen as shown; FIGURE 7c is a graph of responses for the hydrogen sensor from FIGURE 7a at 120° at varying levels of hydrogen as shown; FIGURE 8a is a schematic representation of an early stage of fabrication of an embodiment of the present invention; FIGURE 8b is a schematic representation of an intermediate stage of fabrication of an embodiment of the present invention; FIGURE 8c is a schematic representation of a final stage of fabrication of an embodiment of the present invention; FIGURE 8d is a schematic representation of an embodiment of the present invention configured into an array of nanowires; FIGURE 8e is a graph of test results from an embodiment of the present invention tested at varying hydrogen levels and 103°C, 136°C and 178°C; FIGURE 9 is a schematic representation of an embodiment of the present invention; FIGURE 10a is an illustration of hydrogen sensors used for automobile applications; FIGURE 10b is an illustration of hydrogen sensors within a fuel cell; FIGURE 10c is an illustration of hydrogen sensors used for transformer applications; and FIGURE lOd is an illustration of hydrogen sensors used for home applications. DETAILED DESCRIPTION In the following description, numerous specific details are set forth such as specific alloy combinations, etc. to provide a thorough understanding of the present invention. However, it will be obvious to those skilled in the art that the present invention may be practiced without such specific details. Some details have been omitted in as much as such details are not necessary to obtain a complete understanding of the present invention and are within the skills of persons of ordinary skill in the relevant art. Refer now to the drawings wherein depicted elements are not necessarily shown to scale and wherein like or similar elements are designated by the same reference numeral through the several views. The present invention is directed to an improved apparatus and method for sensing hydrogen gas. The addition of silver to the palladium nanowires significantly increases the operating temperature range of the sensor. The incorporation of silver with palladium also addresses the issue of sensitivity of the nanowires to different levels of hydrogen concentrations. Pure palladium nanowires typically do not provide enough sensitivity to allow detection over a large range of hydrogen concentrations. At room temperature, pure palladium nanowires are able to detect a concentration of about 2% hydrogen. At higher temperatures, pure palladium wires require a higher concentration of hydrogen for detection. However, the incorporation of silver in palladium nanowires provides a greater range of detection suitable to make hydrogen sensors. The substrate for an embodimentcan be any insulating surface such as polymer, glass, silicon, or silicon nitride. A thin layer of titanium is deposited onto the substrate to fonn a conductive area for electroplating. A photoresist pattern is prepared on the top of the substrate by lithography. Palladium or palladium-silver alloy nanoparticles/nanowires are then electroplated on the exposed titanium surface. The palladium electroplating bath contains 1 mM PdCl2, 0.1 M HCl in water. The palladium-silver electroplating bath contains 0.8 mM PdCl2, 0.2 mM AgN03, 0.1 M HCl, 0.1 M NaN03, and 2 M NaCl in deionized water. The nanoparticles/nanowires are deposited at -50 mV vs SCE for 600 sec with one second large overpotential pulse (-500 mV vs SCE). FIGURE 1 shows an image of a nanoparticle thin film that consists of nanoparticles with a 100 nm diameter. FIGURE 2 shows an image of 300 nm palladium nanowires prepared by side wall technique. FIGURE 3 and FIGURE 4 show the response of a palladium-silver alloy hydrogen sensor at 70°C for varying hydrogen concentrations over time. Note that the devices are essentially OFF when no hydrogen is present and palladium alloy-nanocrystals in the device act as an "open circuit" with very-high resistance. When the device is exposed to hydrogen, the palladium alloy-nanocrystals in the device touch each other through expansion of the lattice. This causes any nanogaps in the wires to close (ON state) and the nanowires behave as a "short circuit" with very-low resistance. The sensors have a highly desirable characteristic in that the sensors require essentially zero power in the absence of hydrogen. The sensor acts like an open circuit in the absence of hydrogen and only draws a small amount of power when an alarm condition occurs. This is the ideal situation for a good hydrogen detector: OFF in the absence of hydrogen, and ON only when hydrogen is present. Turning to FIGURE 5 a, a particular embodiment of making a hydrogen sensor involves evaporating a
1000 A layer 302 of titanium onto a polymide film 300 such as Kapton. One of ordinary skill in the art will recognize that any insulating material such as glass or silicon may be substituted for Kapton. Next, a photoresist (not shown) is patterned on the titanium layer 302 in a well-known manner. A layer 304 of nanoparticles of palladium-silver alloy are then electroplated onto the surface. The device is heated to 500°C for 2 hours in air to oxidize the titanium layer. FIGURE 5b displays test results for this embodiment at 100°C. In this test, an exemplary sensor of the instant embodiment was tested for 3 cycles with hydrogen concentrations of 0.5%, 1.5%, and 2%. FIGURE 5c displays results for tests at 120°C with 1% hydrogen concentrations. FIGURE 5c illustrates that the sensor did not degrade after 5 cycling tests. Another embodiment of the present invention is depicted schematically in FIGURE 6a. In this embodiment, a 5000 A layer 602 of SiNx is deposited on a silicon substrate 600. A layer 604 of 1000 A thick titanium is then deposited on layer 602. Using lithography, a pattern (not shown) is created on the substrate. A thin film 606 of palladium-silver nanoparticles is electroplated to layer 604. In one example of the instant embodiment, the palladium-silver alloy was electroplated at 300 μA for 1 second and 20 μA for 600 seconds. Next, oxidizing the titanium 604 forms Tiθ2- In one example, the titanium was exposed to 500°C air overnight.
Following oxidation of the titanium, another layer 608 of palladium-silver is deposited to layer 606. In one example, palladium-silver was electroplated at 300 μA for 1 second and 20 μA for 200 seconds. FIGURES 6b-6d illustrate results achieved by testing the exemplary embodiment as depicted in
FIGURE 6a. FIGURE 6b illustrates test results performed at room temperature. The device was first tested at room temperature with hydrogen concentrations ranging from 0.5% to 4%. The voltage applied was 0.1V. The current was about 3E-6A with no hydrogen present. The current rose to 7E-6A at 0.5% hydrogen and 1E-5A at 1% hydrogen. The response was slowly saturated at around 3% hydrogen concentration with a current of 1.2E- 5 A, about 400% of the current at OFF state. FIGURE 6c illustrates test results performed at 70°C for the exemplary embodiment as depicted in
FIGURE 6a. At 120°C, the sensor did not respond to hydrogen. The results shown in FIGURE 6c were achieved after slowly reducing the temperature from 120°C to 70°C. FIGURE 6c illustrates that the sensor was essentially non-operational when the temperature was raised to 120°C, but the sensor regained its operation when the temperature was reduced to 70°C. FIGURE 6d illustrates test results for the embodiment depicted in FIGURE 6a after cooling the device from 70°C to room temperature. The device responded to hydrogen with similar magnitude as the previous test at room temperature, illustrated in FIGURE 6b. In the OFF state, the device had a current of about 1.5E-6A. In the ON state, the current was about 7E-6A at 4% hydrogen. This result showed about 400% change in magnitude between OFF and ON states. The difference in current of the OFF state before and after high temperature testing might indicate some degradation, but the relative changed in resistance (400%) was about the same. The embodiment depicted in FIGURE 6a provides a way to prepare a hydrogen sensor without using the transfer method. However, unlike using Kapton, the tested device did not work at 120°C. In fact, the sensitivity of the sensor decreased as the temperature increased. Nevertheless, the sensor showed good sensitivity at room temperature with more stable and less noisy response curves. Another embodiment of the present invention is shown schematically in FIGURE 7a. FIGURE 7a shows a silicon substrate 700 deposited with 5000 A of SiNx, forming layer 702. Next, 200 A of titanium is deposited to form layer 704. A layer 706 of palladium-silver is electroplated to titanium layer 704. In an example of the instant embodiment, palladium-silver was electroplated at 300 μA for 1 second and 20μA for 600 seconds. Test results of an example of the instant embodiment are illustrated in FIGURE 7b. The results in FIGURE 7b were achieved at room temperature. A second experiment performed at 120°C yielded the results shown in FIGURE 7c. Although at 120°C the change between OFF state to ON state was not very large, the device from this embodiment was able to detect hydrogen at 0.5% concentration both at room temperature and 120°C. Another embodiment of the present invention is depicted schematically in FIGURES 8a-8e. In this embodiment, Si02 is deposited on a silicon substrate 800 to form a 5000 A layer 802 of Si02. One of ordinary skill in the art recognizes that SiNx or other suitable materials may be substituted for Si02. Titanium 200 A thick is deposited to form layer 804. Next, the photoresist 806 is deposited on the substrate and patterned by photolithography leaving the assembly substantially as depicted in FIGURE 8b, with layer 804 having two side- walls. Nanowires 808 made from palladium-silver alloys are then electroplated onto the side-walls of the titanium 804. In one example of the instant embodiment, palladium-silver was electroplated using a side-wall plating technique at 300 μA for 1 second and 20 μA for 600 seconds. Since the sidewall of the metal is the only place exposed to the electrolytic bath, the palladium-silver will be deposited on the sidewall only and form the nanowires at the edge of the metal lines. Next, the remaining titanium 804 is etched away, leaving the assembly as shown in FIGURE 8c. Alternatively, the titanium 804 could be oxidized at high temperature or left on the substrate. The sensor is functional witliout removing the metal layer, but has a low S N ratio. The removal of the metal layer provides higher S/N ratio. The side-wall plating technique for an embodiment as shown in Figure 8(c) and operational at high temperatures can be accomplished as follows: the substrate can be used as a working electrode in a three- electrode plating system with a saturated calomel electrode (SCE) as the reference electrode and platinum wire as the counter electrode. Using conventional electrochemical deposition/plating, the three electrodes can be immersed in a palladium silver alloy plating solution bath solution consisting of 2.5 mM of PdC12, 0.5 mM of AgΝ03, 0.05 M of NaN03, 0.05 M of HCl, and 2 M (20g in lOOmL) of NaCl in water. A standard electrochemical program, namely chronopotentiometry can be used for this process. For formation of the nanowires on the substrate, the electrochemical plating conditions can be as follows: using a pure palladium plating bath, apply -300 μA for 10 sec, then apply -20 μA for 450sec. After electroplating, the substrate can be immersed in acetone, followed by IPA and water to remove the photoresist on the surface. The side-wall plating technique for an embodiment as shown in Figure 8(c) and operational at room temperature can be accomplished as follows: the substrate can be used as a working electrode in a three- electrode plating system with a saturated calomel electrode (SCE) as the reference electrode and platinum wire as the counter electrode. Using conventional electrochemical deposition/ plating, the three electrodes can be immersed in a pure palladium plating bath consisting of 1 mM of PdCl2 and 0.1 M HCl in water. A standard electrochemical program, namely chronopotentiometry can be used for this process. For formation of the nanowires on the substrate, the electrochemical plating conditions can be as follows: using pure palladium plating bath, apply -300 μA for 10 sec, then apply -20 μA for 450sec. After electroplating, the substrate can be immersed in acetone, followed by IPA and water to remove the photoresist on the surface. FIGURE 8d depicts an embodiment created by patterning the substrate using photolithography to electroplate multiple nanowires 808 to the side- walls of titanium strips 804. FIGURE 8(d) is made in the similar fashion as outlined in 8(a) to 8(c); however, FIGURE 8(d) shows multiple nanowires arranged in an array. A hydrogen sensor is utilized by connecting conductors to the ends of the array of nanowires which electrically connects the nanowires in parallel. In an embodiment, silver paste is applied to the ends of the array of nanowires and separate wires are connected to the silver paste on each end. A voltage is then applied across the parallel nanowires, and the resultant current is measured to determine whether there is hydrogen present. Using palladium-silver alloy nanowires, the current is higher in the presence of hydrogen than in the absence of hydrogen. The particular embodiment as described in Figure 8d can be fabricated as follows: 5000 A Si02, item 802, is deposited on a 4 inch silicon wafer, item 800, using a E-beam evaporator followed by a layer of 200 A titanium, item 804. The substrate is then coated with a photoresist hexamethylenedisilane (HMDS) for 30 seconds at 700 RPM followed by a positive photoresist for 90 seconds at 3000 RPM. The substrate is then exposed under UV light with a homemade H-Sensor 5mm line mask (not shown) for 25 sec and further developed by photoresist developer diluted for 40 seconds. The substrate is then rinsed with water for 30 minutes, dried using a blow drier, and heated in an oven for 10 minutes at 120°C. The titanium layer not covered by the photo resist is then etched away by a titanium etchant, exposing the sidewall of the titanium layer over the entire substrate. The pattern is exposed under UV with homemade mask (not shown) for 25 seconds after proper alignment of the sensor pattern. The substrate is then developed by 400 K developer diluted for 40 seconds. The substrate is then rinsed with water for 30 minutes, dried using a blow drier, and heated in an oven for 10 minutes at 120°C. The sidewall plating technique is then used to electroplate the nanoparticles 808 onto the substrate.
After electroplating, the substrate is immersed in acetone followed by IPA and water to remove the photoresist from the surface. In an embodiment, the nanowires 808 are separated from the titanium 804 without removing them from 802. FIGURE 8e shows the results from testing an example of the embodiment as depicted in FIGURE 8c. The test began at room temperature. The temperature was increased to 103°C, then 136°C, and then 178°C. As the temperature increased, the current increased due to the larger thermal expansion coefficient of palladium- silver compared to SiNx. The palladium-silver nanowires 808 expanded faster than the substrate and the resistance lowered. With the test chamber at 103°C, the sensor was tested with hydrogen concentrations of 0.25%), 1.0%, and 4.0%). As FIGURE 8e shows, the sensor responded to each concentration level. The device was functional even at 178°C. FIGURE 9a - 9b depicts another embodiment of the present invention. The embodiment of FIGURE 9a - 9b produces response curves typical of other embodiments described herein, but the embodiment in FIGURE 9a - 9b is suitable for fabricating hydrogen sensors to be operable both in ambient air and under oil, such as transformer oil. The embodiment of FIGURE 9a - 9b can be fabricated using photolithography as follows: First, a 5000 A layer 912 of silicon nitride is deposited on a 4 inch silicon wafer 900 using a E-beam evaporator followed by a layer 902 of 200°A titanium. The substrate is then coated with a photoresist hexamethylenedisilane (HMDS) for 30 seconds at 700 RPM followed by a positive photoresist for 90 seconds at 3000 RPM. The substrate is then exposed under UV light with homemade H-Sensor 5mm line mask (not shown) for 25 sec and further developed by photoresist developer diluted for 40 seconds. The substrate is then rinsed with water for 30 minutes, dried using a blow drier, and heated in an oven for 10 minutes at 120°C. A layer 904 of 100 A chromium and 300 A gold, item 906, is deposited using E-Beam. In an embodiment, the resistance of the substrate can be measured to be less than 10 ohms. The photoresist is lifted off using appropriate stripper followed by heating in oven for 30 minutes at 90°C and subsequent drying. The substrate is then coated with a photo resist 908 for 30 seconds at 700 RPM followed by positive photoresist for 90 seconds at 3000 RPM. The pattern is exposed under UV with homemade mask (not shown) for 25 seconds after proper alignment of the sensor pattern. The substrate is then developed by photoresist developer diluted for 40 seconds. The substrate is then rinsed with water for 30 min, dried using a blow drier, and heated in an oven for 10 minutes at 120°C. A plating technique is then used to electroplate the nanoparticles 910 onto the substrate. Note, in an embodiment the sidewall plating technique is not used because the titanium is not etched in this process. After electroplating, the substrate was immersed in acetone, followed by IPA and water to remove the photoresist on the surface. FIGURES 10a- lOd show various applications for the present invention. FIGURE 10a depicts an application for utilizing hydrogen sensors to monitor hydrogen levels inside a vehicle and within a fuel cell. Sensors in the vehicle cabin monitor to ensure that dangerous concentrations of hydrogen do not create an unsafe condition for drivers and passengers. Sensors within the fuel cell ensure proper operation and health of the fuel cell. FIGURE 10b represents a fuel cell used to monitor the health of the fuel cell. The hydrogen sensor is placed to ensure proper hydrogen levels in the intake and to monitor the hydrogen level in the exhaust. Similarly, FIGURE lOd depicts an application for monitoring hydrogen concentration in and around a home utilizing a fuel cell. Hydrogen sensors in the home monitor for dangerous levels of hydrogen to protect occupants by preventing explosive buildups of hydrogen. FIGURE lOc depicts yet another application for hydrogen sensors in power equipment. As discussed previously, power transformers and switchmg equipment are often filled with insulating oil. A breakdown or contamination of the insulating oil can cause short circuits and lead to dangerous explosions and fires. Some potential failures are predicted by monitoring for buildups of hydrogen and other gases in the transformer oil. FIGURE 10c shows a hydrogen sensor placed under the insulating oil of a transformer. Another sensor could be placed above the oil to monitor hydrogen levels. One of ordinary skill in the art recognizes that hydrogen sensors may also be placed in any application where a buildup of hydrogen signals a dangerous condition. The present invention relates to using palladium-silver alloy thin film (or array, network) and nano/meso wires as an active element for hydrogen sensing applications. Embodiments of the present invention can detect 0.25% hydrogen in nitrogen. With the present invention, by preparing a very thin layer of metal (for example, titanium) or oxidizing a titanium layer to Ti02 and preparing conductive palladium or palladium-silver nanostructures on the less conductive titanium or Ti02 surface, there is no need for the transfer process which caused degradation of the sensor at high temperature. Test results show that palladium or palladium-silver nanoparticles (or nanowires) on titanium (or Ti02) can be used to detect very low concentration (0.25%) of hydrogen at very high temperature (178°C). Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

WHAT IS CLAIMED IS:
1. An apparatus for sensing hydrogen comprising: a substrate wherein a plurality of nanoparticles is deposited on the substrate to form at least one nanoparticle path, wherein the at least one nanoparticle path exliibits an increase in electrical conductivity in the presence of hydrogen and a decrease of electrical conductivity in the absence of hydrogen and wherein the at least one nanoparticle path was formed in close proximity to the substrate using a side-wall plating technique, and wherein the electrical conductivity of the at least one nanoparticle path is readily discernable over the electrical conductivity of the substrate due to the non-conductive nature of the substrate.
2. The apparatus of claim 1 wherein the at least one nanoparticle path forms at least one nanowire.
3. The apparatus of claim 1 wherein the plurality of nanoparticles are deposited to at least one side- wall of a metal layer; and wherein the metal layer is on the substrate while depositing the plurality of nanoparticles and the metal layer is removed from the substrate after depositing the plurality of nanoparticles.
4. The apparatus of claim 1 wherein the at least one nanoparticle paths is composed of a combination of Pd and Ag.
5_ The apparatus of claim 1 wherein the substrate is composed of SiNx
The apparatus of claim 1 wherein the substrate is composed of S-O2.
7. An apparatus for sensing hydrogen comprising: a semiconductor substrate having a top surface; a layer of Ti02 disposed on the top surface of the semiconductor substrate, wherein the layer of Ti02 has a top surface; and a nanoparticle path disposed on the top surface of the layer of Ti02 wherein the nanoparticle path has a top surface and wherein the nanoparticle path exhibits an increase in conductivity in the presence of hydrogen.
8. The apparatus of claim 7 wherein the layer of Ti02 is formed by oxidizing a layer of Ti having a top surface and wherein the layer of Ti is oxidized after the nanoparticle path is disposed on the top surface of the layer of Ti.
9. The apparatus of claim 7 comprising a second nanoparticle path disposed on the top surface of the nanoparticle path after the layer of Ti02 is formed by oxidizing the layer of Ti.
10. An apparatus for sensing hydrogen comprising: a semiconductor substrate having a top surface; a layer of SiNx disposed on the top surface of the semiconductor substrate wherein the layer of SiNx has a top surface; a Ti layer disposed on the top surface of the SiNx layer wherein the Ti layer has at least one side-wall; and a plurality of nanoparticles disposed on the top surface of the SiNx wherein the plurality of nanoparticles form a path of nanoparticles having higher conductivity in the presence of hydrogen than in the absence of hydrogen.
1 1. The apparatus of claim 10 wherein the plurality of nanoparticles is disposed on the SiNx layer by side- wall plating the plurality of nanoparticles to the at least one side- wall of the Ti layer.
12. An apparatus for sensing hydrogen comprising; a semiconductor substrate having a top surface; a first metal layer deposited on the top surface of the semiconductor substrate wherein the first metal layer has a top surface; a second metal layer deposited on the top surface of the first metal layer creating a covered region of the top surface of the first metal layer and an exposed region of the top surface of the first metal layer, and wherein the second metal layer has at least one side-wall; and a plurality of nanoparticles disposed to the at least one side-wall of the second metal layer and a plurality of nanoparticles disposed to the exposed region of the first metal layer, wherein the plurality of nanoparticles form at least one nanoparticle path exliibiting increased conductivity in the presence of hydrogen.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006121349A1 (en) * 2005-05-09 2006-11-16 Nano Cluster Devices Limited Hydrogen sensors and fabrication methods
US7762121B2 (en) 2003-06-03 2010-07-27 Applied Nanotech Holdings, Inc. Method and apparatus for sensing hydrogen gas
US8715536B2 (en) 2009-09-14 2014-05-06 Industrial Technology Research Institute Conductive material formed using light or thermal energy, method for forming the same and nano-scale composition

Families Citing this family (50)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9056783B2 (en) 1998-12-17 2015-06-16 Hach Company System for monitoring discharges into a waste water collection system
US8958917B2 (en) 1998-12-17 2015-02-17 Hach Company Method and system for remote monitoring of fluid quality and treatment
US7454295B2 (en) 1998-12-17 2008-11-18 The Watereye Corporation Anti-terrorism water quality monitoring system
US20060011487A1 (en) * 2001-05-31 2006-01-19 Surfect Technologies, Inc. Submicron and nano size particle encapsulation by electrochemical process and apparatus
US6890412B2 (en) * 2001-08-27 2005-05-10 Surfect Technologies, Inc. Electrodeposition apparatus and method using magnetic assistance and rotary cathode for ferrous and magnetic particles
JP2006513041A (en) * 2002-12-05 2006-04-20 サーフェクト テクノロジーズ インク． Coated magnetic particles and their applications
US7001669B2 (en) * 2002-12-23 2006-02-21 The Administration Of The Tulane Educational Fund Process for the preparation of metal-containing nanostructured films
US8920619B2 (en) 2003-03-19 2014-12-30 Hach Company Carbon nanotube sensor
US20070125153A1 (en) * 2005-10-21 2007-06-07 Thomas Visel Palladium-Nickel Hydrogen Sensor
US20070240491A1 (en) * 2003-06-03 2007-10-18 Nano-Proprietary, Inc. Hydrogen Sensor
US7399400B2 (en) * 2003-09-30 2008-07-15 Nano-Proprietary, Inc. Nanobiosensor and carbon nanotube thin film transistors
US20050244811A1 (en) * 2003-12-15 2005-11-03 Nano-Proprietary, Inc. Matrix array nanobiosensor
WO2005076977A2 (en) * 2004-02-04 2005-08-25 Surfect Technologies, Inc. Plating apparatus and method
KR20080036627A (en) * 2005-08-03 2008-04-28 나노-프로프리어터리, 인크. Continuous range hydrogen sensor
NL1030299C2 (en) * 2005-10-28 2007-05-03 Advanced Chem Tech Optical switching device.
US8903474B2 (en) * 2005-12-06 2014-12-02 Pen Inc. Analysis of gases
KR100779090B1 (en) * 2006-07-18 2007-11-27 한국전자통신연구원 Gas sensor using zinc oxide and method of forming the same
KR100870126B1 (en) 2006-12-27 2008-11-25 연세대학교 산학협력단 A method for manufacturing hydrogen sensors by using Pd nano wire
JP4263747B2 (en) * 2007-01-26 2009-05-13 株式会社日本製鋼所 Hydrogen remaining amount sensor
US7810314B2 (en) * 2007-06-12 2010-10-12 Ford Global Technologies, Llc Approach for controlling particulate matter in an engine
US8519446B2 (en) * 2007-08-29 2013-08-27 Applied Nanotech Holdings, Inc. Etch resistant gas sensor
US20090058431A1 (en) * 2007-08-29 2009-03-05 Applied Nanotech Holdings, Inc. Etch resistant gas sensor
EP2083262B1 (en) * 2008-01-28 2014-05-07 Micronas GmbH Resistive hydrogen sensor
CN102037349A (en) * 2008-04-06 2011-04-27 H2Scan公司 Protective coatings for solid-state gas sensors employing catalytic metals
US8028561B2 (en) * 2008-09-30 2011-10-04 Qualitrol Company, Llc Hydrogen sensor with air access
US8501269B2 (en) * 2008-10-16 2013-08-06 Apollo, Inc. Sensitive materials for gas sensing and method of making same
US8441361B2 (en) * 2010-02-13 2013-05-14 Mcallister Technologies, Llc Methods and apparatuses for detection of properties of fluid conveyance systems
US8312759B2 (en) * 2009-02-17 2012-11-20 Mcalister Technologies, Llc Methods, devices, and systems for detecting properties of target samples
US20120036919A1 (en) * 2009-04-15 2012-02-16 Kamins Theodore I Nanowire sensor having a nanowire and electrically conductive film
KR101283685B1 (en) * 2009-11-23 2013-07-08 한국전자통신연구원 Environment Gas Sensor and Method for Preparing the Same
US20110138882A1 (en) * 2009-12-11 2011-06-16 Electronics And Telecommunications Research Institute Semiconductor gas sensor having low power consumption
US8839658B2 (en) 2011-03-31 2014-09-23 Qualitrol Company, Llc Combination of hydrogen and pressure sensors
US8511160B2 (en) 2011-03-31 2013-08-20 Qualitrol Company, Llc Combined hydrogen and pressure sensor assembly
US8707767B2 (en) 2011-03-31 2014-04-29 Qualitrol Company, Llc Combined hydrogen and pressure sensor assembly
EP2773941A1 (en) * 2011-11-04 2014-09-10 Danmarks Tekniske Universitet Resonant fiber based aerosol particle sensor and method
KR101358245B1 (en) * 2012-03-19 2014-02-07 연세대학교 산학협력단 Hydrogen sensor and method for manufacturing the same
GB2507042B (en) * 2012-10-16 2018-07-11 Schlumberger Holdings Electrochemical hydrogen sensor
US10605795B2 (en) * 2015-02-17 2020-03-31 H2Scan Corporation Method for measuring gas concentrations based on sensor response times
CN108112263B (en) * 2015-08-28 2020-11-03 松下半导体解决方案株式会社 Gas sensor and fuel cell vehicle
JP2017111015A (en) * 2015-12-17 2017-06-22 株式会社日立製作所 Hydrogen measurement device and hydrogen measurement method
CN106018490A (en) * 2016-05-13 2016-10-12 湖北大学 Palladium-silver nano-film hydrogen-sensitive element and manufacturing method
NL2017885B1 (en) * 2016-11-29 2018-06-11 Sencio B V Sensor package and method of manufacturing the same
KR101908373B1 (en) * 2017-03-10 2018-10-17 한국전력공사 System, apparatus and method for monitoring hydrogen gas in transformer
JPWO2019077814A1 (en) * 2017-10-18 2020-11-26 ソニーセミコンダクタソリューションズ株式会社 Charge detection sensor and potential measurement system
US12111281B2 (en) * 2018-11-21 2024-10-08 Hyaxiom, Inc. Hydrogen concentration sensor
US11824238B2 (en) 2019-04-30 2023-11-21 Hyaxiom, Inc. System for managing hydrogen utilization in a fuel cell power plant
US11567022B2 (en) 2019-06-05 2023-01-31 General Electric Company Sensing system and method
US12000794B2 (en) 2020-12-08 2024-06-04 Hyaxiom, Inc. Hydrogen concentration sensor
US11768186B2 (en) 2020-12-08 2023-09-26 Hyaxiom, Inc. Hydrogen concentration sensor
EP4300089A1 (en) * 2021-02-25 2024-01-03 Japan Science and Technology Agency Gas sensor

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030079999A1 (en) 2001-07-20 2003-05-01 The Regents Of The University Of California Hydrogen gas sensor
WO2004020978A2 (en) 2002-08-30 2004-03-11 Nano-Proprietary, Inc. Formation of metal nanowires for use as variable-range hydrogen sensors

Family Cites Families (89)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US23428A (en) * 1859-03-29 lewis
US79999A (en) * 1868-07-14 Improvement in tiee-feime attachment
US139003A (en) * 1873-05-20 Improvement in submerged force-pumps
US132361A (en) * 1872-10-22 Improvement in metallic packings for piston-rods
GB800285A (en) 1956-08-23 1958-08-20 Gen Motors Corp Improvements in or relating to internal combustion engine electric ignition distributor apparatus
US3672388A (en) * 1969-06-19 1972-06-27 Gen Electric Sensor and control system for controlling gas partial pressure
US3864628A (en) * 1973-05-29 1975-02-04 Inst Gas Technology Selective solid-state gas sensors and method
GB1481509A (en) * 1973-07-18 1977-08-03 Nat Res Dev Ion selective electrodes and in methods of measuring the concentrations of ions
US4222045A (en) * 1979-05-04 1980-09-09 Firetek Corporation Capacitive shift fire detection device
US4324760A (en) * 1981-04-01 1982-04-13 General Electric Company Hydrogen detector
US4450007A (en) * 1982-12-13 1984-05-22 Cabot Corporation Process for electroslag remelting of manganese-base alloys
US4583048A (en) * 1985-02-26 1986-04-15 Rca Corporation MSK digital demodulator for burst communications
US4760351A (en) * 1986-08-22 1988-07-26 Northern Illinois University Multiple oscillator device having plural quartz resonators in a common quartz substrate
US4782334A (en) * 1987-08-13 1988-11-01 Meaney Thomas A Vapor or gas detector and alarm system
US5014908A (en) * 1989-11-27 1991-05-14 Emerson Electric Co. Control circuit using a sulphonated fluorocarbon humidity sensor
US5251233A (en) * 1990-12-20 1993-10-05 Motorola, Inc. Apparatus and method for equalizing a corrupted signal in a receiver
US5117441A (en) * 1991-02-25 1992-05-26 Motorola, Inc. Method and apparatus for real-time demodulation of a GMSK signal by a non-coherent receiver
SE513657C2 (en) * 1993-06-24 2000-10-16 Ericsson Telefon Ab L M Method and apparatus for estimating transmitted symbols of a receiver in digital signal transmission
US5962863A (en) * 1993-09-09 1999-10-05 The United States Of America As Represented By The Secretary Of The Navy Laterally disposed nanostructures of silicon on an insulating substrate
US5338708A (en) * 1993-12-20 1994-08-16 E. I. Du Pont De Nemours And Company Palladium thick film compositions
GB9408542D0 (en) * 1994-04-29 1994-06-22 Capteur Sensors & Analysers Gas sensing resistors
US5888614A (en) * 1995-06-06 1999-03-30 Donald H. Slocum Microperforated strength film for use as an anti-infiltration barrier
US5670115A (en) * 1995-10-16 1997-09-23 General Motors Corporation Hydrogen sensor
US5778022A (en) * 1995-12-06 1998-07-07 Rockwell International Corporation Extended time tracking and peak energy in-window demodulation for use in a direct sequence spread spectrum system
FI956360A (en) * 1995-12-29 1997-06-30 Nokia Telecommunications Oy Method for detecting connection set bursts and receivers
ES2251004T3 (en) * 1996-04-04 2006-04-16 Siemens Aktiengesellschaft PROCEDURE FOR PARAMETRIZATION OF A RECEIVER EQUIPMENT, AS WELL AS THE CORRESPONDING RECEIVING EQUIPMENT AND RADIO STATION.
US6652967B2 (en) * 2001-08-08 2003-11-25 Nanoproducts Corporation Nano-dispersed powders and methods for their manufacture
US5905000A (en) * 1996-09-03 1999-05-18 Nanomaterials Research Corporation Nanostructured ion conducting solid electrolytes
US5886614A (en) * 1997-04-11 1999-03-23 General Motors Corporation Thin film hydrogen sensor
US6231744B1 (en) * 1997-04-24 2001-05-15 Massachusetts Institute Of Technology Process for fabricating an array of nanowires
US6494079B1 (en) * 2001-03-07 2002-12-17 Symyx Technologies, Inc. Method and apparatus for characterizing materials by using a mechanical resonator
US6525461B1 (en) * 1997-10-30 2003-02-25 Canon Kabushiki Kaisha Narrow titanium-containing wire, process for producing narrow titanium-containing wire, structure, and electron-emitting device
US20030135971A1 (en) * 1997-11-12 2003-07-24 Michael Liberman Bundle draw based processing of nanofibers and method of making
US6023493A (en) * 1998-01-20 2000-02-08 Conexant Systems, Inc. Method and apparatus for synchronizing a data communication system to a periodic digital impairment
JP2958452B2 (en) * 1998-02-26 1999-10-06 工業技術院長 Method for producing composite porous sensor
US6006582A (en) * 1998-03-17 1999-12-28 Advanced Technology Materials, Inc. Hydrogen sensor utilizing rare earth metal thin film detection element
DE19819575C1 (en) * 1998-04-30 2000-03-16 Siemens Ag Hydrogen sensor
US6029500A (en) * 1998-05-19 2000-02-29 Advanced Technology Materials, Inc. Piezoelectric quartz crystal hydrogen sensor, and hydrogen sensing method utilizing same
US6120835A (en) * 1998-10-05 2000-09-19 Honeywell International Inc. Process for manufacture of thick film hydrogen sensors
JP3473460B2 (en) * 1998-11-20 2003-12-02 富士電機株式会社 Horizontal semiconductor device
US6277329B1 (en) * 1999-03-22 2001-08-21 Camp Dresser & Mckee Inc. Dissolved hydrogen analyzer
US6465132B1 (en) * 1999-07-22 2002-10-15 Agere Systems Guardian Corp. Article comprising small diameter nanowires and method for making the same
US6450007B1 (en) * 1999-12-01 2002-09-17 Honeywell International Inc. Robust single-chip hydrogen sensor
US6730270B1 (en) * 2000-02-18 2004-05-04 Honeywell International Inc. Manufacturable single-chip hydrogen sensor
US6634213B1 (en) * 2000-02-18 2003-10-21 Honeywell International Inc. Permeable protective coating for a single-chip hydrogen sensor
EP1261427B1 (en) * 2000-03-02 2011-03-02 Microchips, Inc. Microfabricated devices and methods for storage and selective exposure of chemicals
US6935158B2 (en) * 2000-03-17 2005-08-30 Wayne State University MIS hydrogen sensors
US6893892B2 (en) 2000-03-29 2005-05-17 Georgia Tech Research Corp. Porous gas sensors and method of preparation thereof
US6673644B2 (en) * 2001-03-29 2004-01-06 Georgia Tech Research Corporation Porous gas sensors and method of preparation thereof
US6535658B1 (en) * 2000-08-15 2003-03-18 Optech Ventures, Llc Hydrogen sensor apparatus and method of fabrication
KR20090049095A (en) * 2000-12-11 2009-05-15 프레지던트 앤드 펠로우즈 오브 하버드 칼리지 Nanosensors
EP1215485B1 (en) 2000-12-12 2011-03-16 Sony Deutschland GmbH Selective chemical sensors based on interlinked nanoparticle assemblies
US6594885B2 (en) * 2000-12-26 2003-07-22 General Electric Company Method of making a coil
EP1374309A1 (en) * 2001-03-30 2004-01-02 The Regents Of The University Of California Methods of fabricating nanostructures and nanowires and devices fabricated therefrom
JP2002340830A (en) * 2001-05-11 2002-11-27 Mitsubishi Heavy Ind Ltd Hydrogen gas detecting device and manufacturing method thereof
DE10123876A1 (en) * 2001-05-16 2002-11-28 Infineon Technologies Ag Nanotube array comprises a substrate, a catalyst layer having partial regions on the surface of the substrate, nanotubes arranged on the surface of the catalyst layer parallel
US7055650B2 (en) * 2001-05-17 2006-06-06 Jlg Industries, Inc. Saw accessory for aerial work platform
JP3995082B2 (en) * 2001-07-18 2007-10-24 日鉱金属株式会社 Hafnium silicide target for gate oxide film formation and method of manufacturing the same
EP1278061B1 (en) * 2001-07-19 2011-02-09 Sony Deutschland GmbH Chemical sensors from nanoparticle/dendrimer composite materials
US6843902B1 (en) * 2001-07-20 2005-01-18 The Regents Of The University Of California Methods for fabricating metal nanowires
KR100552661B1 (en) * 2001-10-26 2006-02-20 삼성에스디아이 주식회사 Conductive inorganic nano-particle with good ion conductivity, ion conductive polymer membrane comprising the same and preparing method thereof
US20050072213A1 (en) * 2001-11-26 2005-04-07 Isabelle Besnard Use of id semiconductor materials as chemical sensing materials, produced and operated close to room temperature
US6737286B2 (en) * 2001-11-30 2004-05-18 Arizona Board Of Regents Apparatus and method for fabricating arrays of atomic-scale contacts and gaps between electrodes and applications thereof
AU2003225839A1 (en) * 2002-03-15 2003-09-29 Nanomix. Inc. Modification of selectivity for sensing for nanostructure device arrays
US7522040B2 (en) * 2004-04-20 2009-04-21 Nanomix, Inc. Remotely communicating, battery-powered nanostructure sensor devices
US20030189202A1 (en) * 2002-04-05 2003-10-09 Jun Li Nanowire devices and methods of fabrication
US6788453B2 (en) * 2002-05-15 2004-09-07 Yissum Research Development Company Of The Hebrew Univeristy Of Jerusalem Method for producing inorganic semiconductor nanocrystalline rods and their use
JP2003340830A (en) * 2002-05-29 2003-12-02 Ricoh Co Ltd Method for manufacturing microlens metal dowel die
AU2003269926A1 (en) 2002-07-30 2004-02-16 The Regents Of The University Of California Superlattice nanopatterning of wires and complex patterns
US7237429B2 (en) 2002-08-30 2007-07-03 Nano-Proprietary, Inc. Continuous-range hydrogen sensors
US7287412B2 (en) * 2003-06-03 2007-10-30 Nano-Proprietary, Inc. Method and apparatus for sensing hydrogen gas
US20040071951A1 (en) * 2002-09-30 2004-04-15 Sungho Jin Ultra-high-density information storage media and methods for making the same
JP5025132B2 (en) 2002-10-29 2012-09-12 プレジデント・アンド・フェローズ・オブ・ハーバード・カレッジ Manufacture of carbon nanotube devices
US7052588B2 (en) * 2002-11-27 2006-05-30 Molecular Nanosystems, Inc. Nanotube chemical sensor based on work function of electrodes
US7163659B2 (en) * 2002-12-03 2007-01-16 Hewlett-Packard Development Company, L.P. Free-standing nanowire sensor and method for detecting an analyte in a fluid
US7001669B2 (en) * 2002-12-23 2006-02-21 The Administration Of The Tulane Educational Fund Process for the preparation of metal-containing nanostructured films
US6770353B1 (en) * 2003-01-13 2004-08-03 Hewlett-Packard Development Company, L.P. Co-deposited films with nano-columnar structures and formation process
US20040173004A1 (en) 2003-03-05 2004-09-09 Eblen John P. Robust palladium based hydrogen sensor
US20070125153A1 (en) * 2005-10-21 2007-06-07 Thomas Visel Palladium-Nickel Hydrogen Sensor
US20070240491A1 (en) * 2003-06-03 2007-10-18 Nano-Proprietary, Inc. Hydrogen Sensor
US7047792B1 (en) * 2003-07-07 2006-05-23 University Of South Florida Surface acoustic wave hydrogen sensor
SE526927C2 (en) * 2003-11-24 2005-11-22 Hoek Instr Ab Real-time analysis of gas mixtures
US20060289351A1 (en) * 2004-07-02 2006-12-28 The University Of Chicago Nanostructures synthesized using anodic aluminum oxide
KR20080036627A (en) 2005-08-03 2008-04-28 나노-프로프리어터리, 인크. Continuous range hydrogen sensor
EP1946070B1 (en) 2005-09-22 2015-05-20 Applied Nanotech Holdings, Inc. Hydrogen sensor
KR200415359Y1 (en) 2006-02-22 2006-05-02 유서종 Comp for scalp treatment
JP4262265B2 (en) * 2006-06-20 2009-05-13 キヤノン株式会社 Semiconductor integrated circuit
GB0800285D0 (en) 2008-01-09 2008-02-13 Joinson Kenneth Grit repellent sock
KR100851621B1 (en) 2008-04-25 2008-08-12 아이닉스 주식회사 Alopecia-healing comb using laser

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030079999A1 (en) 2001-07-20 2003-05-01 The Regents Of The University Of California Hydrogen gas sensor
WO2004020978A2 (en) 2002-08-30 2004-03-11 Nano-Proprietary, Inc. Formation of metal nanowires for use as variable-range hydrogen sensors

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
FAVIER ET AL., SCIENCE, vol. 293, 21 September 2001 (2001-09-21)
See also references of EP1629259A4

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7762121B2 (en) 2003-06-03 2010-07-27 Applied Nanotech Holdings, Inc. Method and apparatus for sensing hydrogen gas
WO2006121349A1 (en) * 2005-05-09 2006-11-16 Nano Cluster Devices Limited Hydrogen sensors and fabrication methods
US8715536B2 (en) 2009-09-14 2014-05-06 Industrial Technology Research Institute Conductive material formed using light or thermal energy, method for forming the same and nano-scale composition

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