WO2006121349A1 - Capteurs d'hydrogene et leurs methodes de fabrication - Google Patents

Capteurs d'hydrogene et leurs methodes de fabrication Download PDF

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Publication number
WO2006121349A1
WO2006121349A1 PCT/NZ2006/000101 NZ2006000101W WO2006121349A1 WO 2006121349 A1 WO2006121349 A1 WO 2006121349A1 NZ 2006000101 W NZ2006000101 W NZ 2006000101W WO 2006121349 A1 WO2006121349 A1 WO 2006121349A1
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film
clusters
contacts
hydrogen
conduction
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PCT/NZ2006/000101
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English (en)
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Simon Anthony Brown
Andreas Lassesson
Joris Van Lith
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Nano Cluster Devices Limited
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Publication of WO2006121349A1 publication Critical patent/WO2006121349A1/fr

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    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
    • G08B17/117—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means by using a detection device for specific gases, e.g. combustion products, produced by the fire
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D21/00—Processes for servicing or operating cells for electrolytic coating
    • C25D21/12—Process control or regulation
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/003—Electroplating using gases, e.g. pressure influence
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D7/00—Electroplating characterised by the article coated
    • C25D7/006—Nanoparticles
    • 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

Definitions

  • the present invention relates to methods of preparing cluster films and the fluid sensors formed by such methods. More particularly but not exclusively the invention relates to a method of preparing such structures by the assembly of conducting nanoparticles.
  • the lattice constant of the palladium crystal in the ⁇ phase is 3.5% larger than that of the ⁇ phase.
  • the change happens over a relatively small pressure range, which also means that the mechanical and electrical properties of Pd are here most sensitive to the P H2 -
  • the specific pressure at which the phase change happens is strongly temperature dependent, but at 2O 0 C it is around 2x10 3 Pa [I].
  • Poisoning of the palladium surface is caused by physisorbed and chemisorbed molecules.
  • Physisorbed molecules like H 2 O, O 2 , CO and CH 2 can be replaced by hydrogen by subjecting the surface to a high hydrogen pressure.
  • Chemisorbed molecules like H 2 S and SO 2 are very difficult to remove. All these molecules prevent the hydrogen from diffusing into the bulk, therefore they increase the response time of the hydrogen concentration in the bulk to a change in hydrogen pressure from the outside. Some molecules even reduce the response and thus pose a real problem for thin film Pd sensors.
  • US patent application 2003/0079999 discloses a hydrogen sensor which achieves a decrease in resistance on absorption of hydrogen into the sensor material.
  • the prior art relies on an array of wires which are incomplete (i.e. where at least some of the wires have gaps).
  • the methodology of the invention relied on electrodeposition to form the wires on surface steps on a graphite substrate and the wires had to be lifted off the graphite substrate in an epoxy matrix.
  • US patent application 2005/6849911 describes a hydrogen sensor and/or switch from a number of columns of Pd-Ag alloy nanoparticles fabricated using electrodeposition.
  • US patent applications 2005/0155858, 2004/0261500 and 2004/0070006 describe variations on that theme.
  • Barr [3] looked at the conductance-temperature characteristic of discontinuous palladium films by electron beam evaporation of atomic vapour onto cooled rock salt substrate.
  • the model that Barr uses to describe his data assumes that the electrical conduction is due to quantum mechanical tunnelling.
  • the model assumes two competing effects on exposure to hydrogen. First surface absorption of hydrogen by palladium decreases the Fermi levels of the palladium islands and thus increases the effective barrier height between two islands, decreasing the conductance. Second, a hydrogen induced expansion of the lattice constant decreases the barrier width and hence increases the conductance.
  • a further series of papers from Binghamton University [4,5,6] discuss the effects of hydrogen absorption on the electrical conduction of discontinuous palladium films on glass substrates within the model of Barr [3].
  • An alternative object is to provide an alternative method for the preparation of nanoscale fluid sensors particularly hydrogen sensors, using metal clusters.
  • a hydrogen sensor device comprising a non-contiguous film(s) of nanoscale metal or semiconductor clusters running substantially between two or more contacts and responsive to the presence of hydrogen gas, and a detector in communication with the contacts such that the contacts and the non-contiguous film(s) form a circuit.
  • the response of the device to the presence of hydrogen gas is a change in electrical resistivity between the two or more contacts, where the conduction is due to one of the following processes: ohmic conduction within the film between the two or more contacts; tunnelling conduction within the film between the two or more contacts; a combination of ohmic and tunnelling conduction within the film between the two or more contacts.
  • the non-contiguous film(s) comprises a series of networks of metal or semiconductor clusters on an insulating or semiconducting substrate.
  • the clusters are of palladium or an alloy thereof.
  • the clusters comprise palladium mixed with one or more of silver, rhodium, ruthenium, yttrium and/or nickel.
  • the clusters are of yttrium, or palladium coated yttrium.
  • the intermediate film is discontinuous.
  • the intermediate film is metallic and the principal mode of conduction between the plurality of particles making up the intermediate film is tunnelling conduction.
  • one or more gap(s) in the noncontiguous film(s) close to form at least one continuous link between the contacts thereby decreasing the resistivity of the circuit due to ohmic conduction.
  • the gap(s) in the film open thereby increasing the resistivity of the circuit.
  • the width of the gap(s) in the non-contiguous film(s) will decrease thereby decreasing the resistivity of the circuit due to tunnelling conduction.
  • the width of the gap(s) in the film may increase thereby increasing the resistivity of the circuit.
  • the width of at least some of the gap(s) in the non-contiguous film(s) decrease thereby decreasing the resistivity of the circuit due to tunnelling conduction, and additionally one or more gap(s) in the non-contiguous film(s) close to form at least one continuous link between the contacts thereby decreasing the resistivity of the circuit due to the formation of an ohmic conduction path.
  • the number of discontinuous links is sufficiently large that tunnelling conduction dominates the conductive properties of the film.
  • tunnelling conduction is substantially the sole means of conduction between the contacts upon exposure to hydrogen gas.
  • the non-contiguous film(s), or the non-contiguous film(s) together with the intermediate film comprises a network of clusters whose surface coverage in the region between the contacts is close to the percolation threshold in two dimensions.
  • the non-contiguous film(s), or the non-contiguous film(s) together with the intermediate film comprise a network of particles whose volume filling fraction is close to the percolation threshold in three dimensions.
  • the average diameter of the clusters is between 0.3nm and l,000nm. More preferably the average diameter of the clusters is between 0.3nm and lOOnm.
  • the average diameter of the clusters is between 0.3 and 5nm
  • clusters of less than 5nm allows modification or optimisation of the amount of hydrogen gas absorbed.
  • the clusters have been formed by inert gas aggregation.
  • the method of creation of the vapour which aggregates to form the clusters is by thermal evaporation, sputtering, magnetron sputtering (either AC or DC), arc discharge, electron beam heating or laser irradiation.
  • the substrate is selected from one of the group consisting of silicon, silicon nitride, silicon oxide, aluminium oxide, indium tin oxide, germanium, gallium arsenide or another III-V semiconductor, quartz, or glass.
  • the intermediate film is composed of nanoparticles selected from one of the group consisting of Au, Ag, Cu, Sb, Bi or Pb.
  • the nanoparticles of the intermediate film have diameters less than 20nm.
  • the nanoparticles of the intermediate film have diameters less than 5nm.
  • the clusters of the non- contiguous film exist as loosely formed aggregates of more than one cluster, or as coalesced masses or islands of clusters.
  • the mode of conduction between the coalesced masses or islands of clusters of the intermediate film is entirely tunnelling conduction.
  • the aggregates of more than one cluster or the coalesced masses or islands of clusters are separated by gaps smaller than 5nm.
  • a further layer of inert material is present between the non-contiguous film(s) and the intermediate film reducing interaction between the particles of these films.
  • the inert material is an insulating oxide, such as Al 2 O 3 .
  • the device includes a layer or modifying material between the substrate and the non-contiguous film(s) effective to dictate the cluster film structure, such as a polymer or organic compound eg siloxane.
  • a layer or modifying material between the substrate and the non-contiguous film(s) effective to dictate the cluster film structure such as a polymer or organic compound eg siloxane.
  • the device further includes a resist or other organic compound or an oxide or other insulating layer on top of the clusters of the non-contiguous film(s).
  • the resist is capable of stabilising the morphology and properties of the film(s) or of protecting the film(s) from damage or of preventing exposure of the film to one or more fluids.
  • the device further includes an outer barrier selected from one of —
  • an activated carbon outer barrier is provided to prevent species contaminating the non-contiguous film while allowing the passage of hydrogen gas.
  • the device there are a plurality of films between the two or more contacts, preferably arranged in a Wheatstone Bridge configuration.
  • the device there are two contacts which are separated by a distance smaller than 200 microns; more preferably separated by a distance less than 1 OOOnm; even more preferably separated by a distance less than 200nm.
  • the geometry of the contacts has been optimised by percolation theory calculations to result in non-contiguous film(s) at a surface coverage of particles on the substrate of less than the percolation threshold for a macroscopic contact separation.
  • some of the particles of the non-contiguous film(s) are insulated from other particles of the non-contiguous film.
  • the detector may additionally or alternatively measures the impedance of the film(s) between the two or more contacts.
  • the detector may be selected from one of the group of a galvanometer, an ohmmeter, a potentiostat, a lock-in amplifier and a multimeter.
  • more than one may be used in a measurement circuit.
  • a multiplicity of measurements may be made at more than one frequency.
  • the device may be incorporated within a circuit comprising a power source and a means of monitoring the current flowing through the circuit and/or a means of monitoring the voltage substantially across the one or more pairs of contacts.
  • the presence of hydrogen gas triggers an alarm.
  • the device includes a heater element to control the temperature of the film(s), preferably the heater element is used to tune the responsiveness of the non-contiguous film(s) to hydrogen gas.
  • the non-contiguous film is a palladium alloy, and the temperature of operation and/or the alloy composition have been selected in order that the maximal or desired sensitivity of the sensor will occur for the hydrogen pressure range of interest.
  • hydrogen gas sensing apparatus comprising at least hydrogen gas sensing devices having two or more electrical contacts and one or more non-contiguous film(s) of nanoscale metal or semiconductor clusters running substantially between the two or more contacts, connected in a circuit with a power source and a means for monitoring the current flowing through the circuit and / or a means for of monitoring the voltage substantially across the one or more pairs of contacts.
  • the clusters have an average diameter between 0.3 nm and 1,000 nm. More preferably the clusters have an average diameter between 0.5 nm and lOOnm. Additionally or alternatively the clusters have an average diameter between 0.3 nm and 5nm.
  • the clusters have been formed by inert gas aggregation.
  • the method of creation of the vapour which aggregates to form the clusters is by thermal evaporation, sputtering, magnetron sputtering (either AC or DC), arc discharge, electron beam heating or laser irradiation.
  • the clusters are of palladium, or an alloy or palladium or yttrium or palladium coated yttrium.
  • the apparatus further includes an alarm which is triggered when hydrogen gas is present.
  • the one or more hydrogen sensing devices is/are a device disclosed above.
  • the apparatus includes a heater element to control the temperature of the noncontiguous film(s).
  • a heater element to control the temperature of the noncontiguous film(s).
  • at least the hydrogen sensing device(s) are at least partially surrounded by a membrane capable of selectively transmitting gases. Or wherein the hydrogen sensing device is contained within a gas permeable housing, or within a housing having at least a gas permeable window.
  • the apparatus includes contaminant removing species or means selected from one or more of:
  • the apparatus includes or is in communication with other sensors capable of detecting fluids other than hydrogen, e.g. in combination with a H 2 S or SO 2 sensor.
  • a method of preparing a nanoscale hydrogen sensor device comprising the steps of:
  • the step of depositing the plurality of particles between the contacts to achieve the non-continuous film(s) comprises one or both the steps of:
  • the plurality of clusters are of palladium or an alloy thereof, or yttrium, or palladium coated yttrium.
  • the alloy is palladium mixed with one or more of silver, rhodium, ruthenium, yttrium and/or nickel.
  • the clusters have an average diameter between 0.3nm and lOOOnm. More preferably the clusters have an average diameter between 0.5nm and lOOnm. Alternatively or additionally the clusters have an average diameter between 0.3nm and 5nm.
  • the metal clusters are prepared by inert gas aggregation.
  • the method of creation of the vapour which aggregates to form the clusters is by thermal evaporation, sputtering, magnetron sputtering (either AC or DC), arc discharge, electron beam heating or laser irradiation.
  • the step of preparation of the metal clusters and/or control of cluster source parameters and/or use of a subsequent step of cluster size selection allows control of the cluster size and thereby allows control of the characteristics of the sensor device including the mode of conduction which will result upon exposure to hydrogen gas.
  • the metal film is prepared from particles of Au, Ag, Cu, Sb, Bi or Pb.
  • the particles of the metal film have diameters smaller than 20nm. More preferably the particles of the metal film have diameters smaller than 5nm.
  • the particles of the metal film are separated by gaps with dimensions smaller than 5nm.
  • the particles of the metal film has been formed by inert gas aggregation and are deposited by uniform deposition onto the substrate resulting in the aggregation of the particles into coalesced masses or island(s) on the substrate surface.
  • the thin film consists of a siloxane, or a polymer layer.
  • the substrate surface modification to increase or decrease the surface roughness.
  • the roughness of the substrate is used to tailor the cluster film structure after deposition.
  • the roughness of the substrate can be used to tailor the sensor characteristics.
  • the substrate roughness is modified using reactive ion etching or wet chemical etching procedures.
  • the resist or organic compound is PMMA, photoresist or SU8, and the insulating layer is SiO x , SiN or Al x O y .
  • the clusters of the non-contiguous film(s) is/are of palladium or an alloy thereof, or yttrium, or palladium coated yttrium.
  • the clusters of non-contiguous film(s) is/are a palladium alloy of palladium mixed with one or more of silver, rhodium, ruthenium, yttrium and/or nickel.
  • the method includes a step prior to the deposition of the particles of applying a resist or other organic compound or an oxide or other insulating layer to the substrate and then processing using lithography to define a region or regions where the metal clusters once deported will form a continuous or discontinuous web between the contacts, and another region where the metal clusters will be insulated from the conducting network.
  • a nanoscale hydrogen gas sensing device prepared according to the above method.
  • a hydrogen gas sensor device comprising an non-contiguous film of nanoscale metal or - semiconducting clusters running substantially between two contacts on an insulating or semiconducting substrate, the non-contiguous film being responsive to hydrogen gas, an intermediate discontinuous metal film between the non-contiguous film and the substrate, wherein the metal clusters of the non-contiguous film are between 0.3 and lOOOnm in diameter, and wherein the mode of conduction within the intermediate film is tunnelling conduction, whilst the mode of conduction of the non-contiguous film upon exposure to hydrogen gas is one of: ohmic conduction within the film between the two or more contacts; tunnelling conduction within the film between the two or more contacts; - a combination of ohmic and tunnelling conduction within the film between the two or more contacts.
  • the intermediate film is of coalesced gold nanoparticles.
  • the clusters are of palladium or an alloy thereof, are of size between 5 - lOOnm.
  • a method of assessing the hydrogen gas content in an environment including contacting the device of as above and/or apparatus as above with the environment and reading or otherwise assessing the output of the detector.
  • a hydrogen sensor device substantially as herein described with reference to one or more of the Figures and/or Examples.
  • Hydrogen sensing apparatus substantially as herein described with reference to one or more of the Figures and/or Examples.
  • Nanoscale as used herein has the following meaning - having one or more dimensions in the range 0.1 to 1000 nanometres.
  • Nanoparticle as used herein has the following meaning - a particle with dimensions in the range 0.1 to 1000 nanometres, which includes atomic clusters formed by inert gas aggregation or otherwise.
  • Nanowire as used herein has the following meaning - a pathway formed by the assembly nanoparticles which is electrically conducting (via ohmic conduction or tunnelling conduction, for example).
  • Contact as used herein has the following meaning - an area on a substrate, usually but not exclusively comprising an evaporated metal layer, whose purpose is to provide an electrical connection between the nanowire or cluster deposited film and an external circuit or any other electronic device. A single contact has a width, w; in respect of two contacts they are separated by a separation L.
  • “Atomic Cluster” or “Cluster” as used herein has the following meaning - a nanoscale aggregate of atoms formed by any gas aggregation or one of a number of other techniques [9].
  • Substrate as used herein has the following meaning - a material comprising one or more layers which is used as the structural foundation for the fabrication of the device.
  • the substrate may be modified by the deposition of electrical contacts, by doping or by lithographic processes intended to cause the formation of surface texturing.
  • Conduction as used herein has the following meaning - electrical conduction which includes ohmic conduction and tunnelling conduction.
  • the conduction may be highly temperature dependent as might be expected for tunnelling devices or a semiconducting nanowire as well as only moderately temperature dependent as might be expected for metallic conduction.
  • Tunneling conduction is conduction by quantum mechanical transport of electrons through a classically insulating barrier between two classically conducting materials or particles.
  • Ohmic conduction as used herein describes all other forms of conduction, excluding tunnelling conduction.
  • Non-contiguous film means a film made up of individual units which may be part of a connected network. It is not restricted to a single linear form but may be direct or indirect. It may also have side branches or other structures associated with it. The individual units may or may not be fully coalesced and the film has at least a limited number of critical pathways.
  • the film may be homogeneous or inhomogeneous.
  • the film may be either non-conducting or conducting (either by ohmic or tunnelling conduction) in the absence of the fluid to be detected (hydrogen gas).
  • the film may be a percolating film close to the percolation threshold, with coverage either above or below the percolation threshold.
  • Percolation Theory as used herein has the following definition- theory relating to the formation of connected structures of randomly occupied sites, where there is a regular lattice of sites (site percolation) or not (continuum percolation).
  • Percolation Theory includes all variations on this theory which allow calculations of important parameters such as the conductivity of a network of sites, probability of percolation and correlation length. It also includes variations on this theory which focus on bonds connecting the site (bond percolation).
  • Percolation Threshold as used herein has the following definition- The least occupancy of the available sites in Percolation Theory at which a connected structure of sites exists which spans one of the dimensions of the system and / or allows electrical conduction across the system.
  • Fluid as used herein has the following definition - a liquid or gaseous substance, material, element, compound or chemical.
  • Figure 1 Current as a function of time for Pd clusters deposited (at 0.2 A/s) on a single pair of contacts separated by 100 ⁇ m.
  • Figure 3 A typical cluster yield from the Pd source as a function of diameter for two different source settings.
  • Figure 4 Resistance as a function of time for the first exposure of three Pd cluster films, with different initial resistances, to hydrogen.
  • Figure 5 Resistance as a function of time for exposure of a Pd cluster film sensor to hydrogen illustrating the short response time of the sensor.
  • Figure 6 Resistance as a function of time for exposure of a thick Pd cluster film to hydrogen illustrating the long response time of the sensor.
  • FIG. 1 Schematic relationship between external hydrogen pressure and hydrogen concentration in bulk Pd.
  • FIG. 11 Scanning Electron Microscopy image of a Pd cluster film, coverage -0.77, exposed to hydrogen.
  • Figure 15 Schematic representation percolating type sensors.
  • Figure 16 Schematic representation percolating tunnelling type sensors.
  • Figure 17 Schematic representation tunnelling type sensors.
  • Figure 20 Arrhenius type plot with the data of temperature of an Au island film.
  • Figure 22 Resistance of Pd cluster films with Au islands after hydrogen exposure as a function of resistance before hydrogen exposure.
  • Figure 23 Resistance between two contacts (separated by lOO ⁇ m) versus temperature for a Pd cluster film on top of SiO 2 , for a sensor where the resistance increased after the initial hydrogen load.
  • Figure 24 Arrhenius type plot with the data of figure 23.
  • Figure 25 Resistance as a function of time for the first exposure of two Pd cluster films, with Au islands, to hydrogen.
  • Figure 26 The response of a Pd cluster sensor (without Au-islands) to repeated hydrogen loads.
  • Figure 27 The response of a Pd cluster sensor (with Au-islands) to repeated hydrogen loads.
  • Figure 28 Stability sensor response of Pd cluster films, for films with and without a polymer cover layer.
  • Figure 30 Resistance between two contacts (separated by lOO ⁇ m) versus temperature for a Pd cluster film on top of SiO 2 , for a sensor where the resistance dropped after the initial hydrogen load.
  • Figure 31 Photograph of a multiple contact sensor containing three individual sensors.
  • the scale is in millimetres.
  • Figure 32 Relative change in resistance as a function of hydrogen pressure for a Pd cluster film sensor made using clusters with 3.5nm diameter.
  • Figure 33 Relative change in resistance as a function of hydrogen concentration for a pure Pd cluster film sensor shown in comparison to the expected response of Pd-Ag and Pd-Ni alloy cluster film sensors.
  • the present invention relates to a method of fabricating percolating films of nanoclusters which act as fluid sensors.
  • One preferred form of the invention is a hydrogen sensor.
  • All three embodiments are nanoscale embodiments relying on the use of nanoscale metal clusters, preferably formed by inert gas aggregation, to form a non-contiguous film or film(s) between the electrical contacts of the sensing device.
  • these films Upon exposure to the fluid to be sensed (which is typically hydrogen gas) these films will respond in certain ways (dependent upon their arrangement, configuration or mode of preparation) giving rise to detection of the fluid.
  • percolating - tunnelling sensors for example, Figure 16
  • tunnelling sensors for example Figure 17
  • a tunnelling sensor may develop percolating/ohmic conduction paths on exposure to hydrogen.
  • control of the device we can maximise or minimise the contribution of either type of conduction to the way in which the device works.
  • Percolating films of clusters have previously been described in the context of the formation of nanowires [9]. The purpose of this document was to provide a method for the preparation of nanowires which were automatically connected to a pair of contacts so as to remove the laborious manipulation of nanoscale building blocks which is a common obstacle to the commercial development of nanoscale devices.
  • a percolating film is comprised of both a very limited number of interconnected pathways (described above as nanowires) and a large number of clusters or isolated pathways which are disconnected from either the contacts, or the nanowires, or both.
  • Figure 15 shows a schematic illustration of a connected pathway (solid line) and several noncontiguous pathways in a percolating film. It is further noted that conduction between isolated pathways or isolated particles may occur by tunnelling conduction.
  • Our novel sensing devices and novel method of preparing these devices rely on the use of nanoscale metal clusters and our ability to control these clusters to form sensors of desired functionality and configuration. Furthermore the combination of cluster deposition technology with lithography and semiconductor device technology is highly advantageous in that is potentially enables ready mass production of the devices.
  • a particular feature of at least preferred embodiments of our technology is the dominance in electrical transport through the devices of tunnelling conduction, which in combination with the change in tunnel barrier width on absorption of hydrogen results in extremely sensitive sensors. Sensors have been achieved whose resistance changes by an order of magnitude on exposure to hydrogen.
  • the advantages of at least preferred embodiments of our technology include that: -
  • the sensors are formed using only simple and straightforward techniques, i.e. cluster deposition and relatively low resolution lithography.
  • the nanocluster transducer is automatically connected to electrical contacts. In-situ monitoring of the electrical current during deposition of the clusters allows the deposition to be controlled to allow formation of a sensor with the desired conducting/ sensing properties.
  • the sensors have an unusually high degree of sensitivity and selectivity.
  • the sensors have a linear response over a substantial part of the hydrogen pressure range of interest. -
  • the sensors work in vacuum and at ambient pressures below atmospheric pressures.
  • the sensors consume little or no electrical power in their ready state (i.e. in the absence of hydrogen).
  • the increase in conductivity of the film may occur because of : i) the connection of previously isolated pathways and clusters to a main conducting path through the percolating film, or ii) the creation of a main conducting path through the percolating film, or iii) a decrease in the size of the gaps between the clusters and a consequent onset of, or increase in, a tunnelling current, or iv) a combination of i-iii above, as discussed in more detail below.
  • a preferred embodiment of the invention is therefore a hydrogen sensor whose sensitivity is tuned via a change of temperature, and which includes a heater and temperature sensor provided to allow control of the temperature.
  • a preferred embodiment of the invention is therefore a hydrogen sensor whose sensitivity is tuned via a change of cluster size.
  • a preferred embodiment of the invention is therefore a hydrogen sensor comprising nanoparticles of such alloy materials. Due to differences in the absorption of hydrogen by alloyed materials, alloying can clearly also be used to control the sensitivity and selectivity of the hydrogen sensor.
  • cluster films between contacts with fixed spacing can be connected in series. In this way the absolute change in resistance of the cluster film series is increased compared to a single cluster film.
  • the contacts can be interdigited to increase the contact area between the cluster film and the contacts. Depending on the readout system that will be used any of these two or a combination can be used to improve fabrication tolerances or signal to noise ratio.
  • IGA inert gas aggregation
  • the metal vapour is often produced by thermal evaporation, but clusters could equally well be formed using cluster sources of any other design, a non-exclusive list of which includes sources which achieve a metal vapour by sputtering, magnetron sputtering (either AC or DC), arc discharge, electron beam heating or laser irradiation, (see e.g. the sources described in the review [10]).
  • the particles are carried through a nozzle by the inert gas stream so that a molecular beam is formed. Particles from the beam can be deposited onto a suitable substrate.
  • a magnetron sputtering source which produces ionised Pd clusters which can readily be mass selected.
  • the Pd clusters are formed in a narrow size range (typically we prefer a mean size l-15nm) and the method is particularly suitable for further mass selection [12] if higher control of the particle size distribution is desired (e.g. a size range 3 ⁇ 0.1nm has been achieved [12]).
  • Figure 3 shows two size distributions created using different source conditions.
  • a preferred embodiment of the invention is one in which electrical transport through the device is by tunnelling conduction, as the modulation of the size of the tunnel gap on absorption of hydrogen results in a dramatic change in electrical resistance.
  • Percolation theory predicts that the variation of conductivity of a percolating film in the range of coverages p>p c is expected to follow the power law relationship ⁇ (p) ⁇ (p -pj' where the exponent t is typically -1.3.
  • the expansion of clusters due to absorption of hydrogen will cause an increase in cluster radius and therefore an increase in surface coverage, p. Due to the form of this relationship, a small change in cluster radius will cause a change in p proportional to the radius squared, and therefore a large increase in (p -p c ) which will lead to a dramatic change in conductivity.
  • films with coverages both just above and just below the percolation threshold are potentially useful as sensors.
  • the sensor will be open circuit prior to exposure to hydrogen, and will become conducting on exposure to hydrogen, resulting in a very large change of resistance.
  • Such films may be advantageous for alarm sensors or when minimising the current flowing is necessary in applications where low power consumption is advantageous.
  • the sensor will be conducting prior to exposure to hydrogen, but will become more conducting on exposure to hydrogen.
  • the senor will have a very small tunnelling current prior to exposure to hydrogen.
  • an increase in tunnelling current may occur because the expansion of the clusters (due to absorption of hydrogen) decreases the size of the tunnelling gap between the clusters. Since the tunnelling current depends exponentially on the gap size, the measured change in resistance may be very large.
  • Such films may be advantageous for alarm sensors or when minimising the current flowing is necessary in applications where low power consumption is advantageous.
  • the scope of the invention includes sensors which include regions in which conduction is by tunnelling, and other regions in which conduction is ohmic. These parts may be arrayed serially, but in the preferred embodiment illustrated in Figure 15 the sensor consists of a limited number of (percolating) paths in which conduction is ohmic while there exist one or more other paths which are discontinuous and in which at least part of the conduction is by tunnelling. In some cases the conduction through the tunnelling paths may exceed or be comparable to the conduction through the ohmic path. In other words in such sensors the conduction upon exposure to the fluid will be contributed to by both ohmic and tunnelling conduction.
  • tunnelling and ohmic conduction cases are for illustrative purposes only, and that there may be examples where tunnelling and ohmic conduction may coexist. This is particularly likely to be the case near to the percolation threshold. For example, if the expansion of the clusters shown in Figure 16 is sufficiently great many of the clusters will make contact with each other and a strongly connected pathway such as that illustrated in Figure 15 may be achieved.
  • the substrate surface between the contacts can be covered with small gold islands by thermal evaporation of a very thin gold layer prior to deposition of the clusters. Due to the surface energies of the materials, Au prefers to form islands on both SiO x and SiN surfaces, rather than a homogeneous thin film. If the coverage of the initial layer of islands is sufficient (but not so high as to cause ohmic conduction) when a voltage is applied between the contacts, there will be a small tunnelling current through the gold islands which can be measured. Then, when clusters are deposited between the contacts, the tunnelling conductance increases exponentially with time (Figure 21).
  • the initial layer of islands are inert and do not respond to hydrogen, while the clusters (larger, lighter in Figure 17) expand on exposure to hydrogen and thereby close, or partially close, the tunnelling gaps.
  • the coverage of the surface by both the Au islands and the Pd clusters can be controlled so as to achieve conduction which is dominated by tunnelling, for relatively sparse coverages.
  • a greater number of clusters and islands are in contact and may form percolating paths which conduct at least partially, or possibly substantially, by ohmic conduction (see B above).
  • Cluster versus atomic deposition Although the preferred method of formation of percolating, percolating-tunnelling, and tunnelling hydrogen sensors is the cluster deposition method described extensively herein, such films can be achieved by other methods, most notably the deposition of atomic vapour which aggregates to form clusters on the substrate. Sensors formed by this and other methods are included within the scope of the claims.
  • the level of anchoring of the cluster to the substrate is of significance. If clusters are strongly anchored to the surface, their mobility will be limited, possibly reducing coalescence with neighbouring clusters and limiting the amount of restructuring of the film during initial exposure to hydrogen. However the clusters ability to expand will be hindered, and the sensitivity of the sensor may be reduced. Improved anchoring can be achieved by, for example, increasing the substrate or cluster temperature during deposition, annealing post deposition, or increasing the kinetic energy of the incident clusters. Conversely, more weakly anchored clusters should provide higher sensitivity due to a greater ability to expand, but a larger initial restructuring of the film.
  • the interaction between the nanoparticles can be modified by changing the physical properties of the surface prior to deposition of the nanoparticles.
  • the surface roughness can be modified by wet-chemical etching steps, or reactive ion etching. Therefore a preferred embodiment of the invention is a hydrogen sensor whose performance is optimized by modifying the surface roughness so as to minimise or at least alter the binding of the clusters to the surface and hence the sensitivity and / or the drift characteristics of the sensors.
  • the interaction between the nanoparticles can also be controlled by the choice of the surface material on which the particles are deposited. This can be realized by depositing a thin film of a specific material on top of the substrate.
  • Non-excluding examples of materials that could have useful properties are polymers, Silica and siloxane.
  • a preferred embodiment of the invention is therefore a hydrogen sensor whose performance is optimized by deposition of a thin film prior to deposition of the nanoparticles.
  • the restructuring of the films observed after the completion of cluster deposition may cause an increase in the size of the clusters observed on the surface, and consequent change in the surface coverage. Sensors comprising such restructured cluster deposited films are included in the scope of this application.
  • the temperature considerations discussed above may be used to control the change in cluster diameter.
  • Coatings Stability is a key requirement for application of the hydrogen sensors. Because of the small size of the nanoparticles, there are many processes which can lead to long term instability or irreversible response of the sensor film to consecutive exposures to hydrogen. Examples of such processes are hydrogen induced dislocation of the particles, migration of the particles over the surface and hydrogen induced or intrinsic coalescence of particles.
  • One method for the alleviation of such problems is the coating of the sensor surface with a material which inhibits motion of the nanoparticles.
  • Figure 28 shows the stability of the response of two comparable sensors with and without a photoresist overlayer. Application of the overlayer significantly improves the stability of the sensor response.
  • a preferred embodiment of the invention is therefore a hydrogen sensor whose stability is improved by application of an overlayer after the deposition of the nanoparticles.
  • the overlayer may be of many materials including for example inorganic, insulating films such as SiO x , or Al 2 O 3 , but we have focussed on the use of polymeric materials such as photoresist, SU8 and PMMA which can be applied by depositing a drop on the surface or by spin coating.
  • Poisoning of the surface by molecules abundant in ambient atmosphere can reduce the magnitude and increase the time of the response of the hydrogen sensor.
  • the sensor can be covered with a protective layer which is permeable for hydrogen, but not for these pollutants.
  • the literature contains many concepts and designs for membranes which are permeable to hydrogen, and not to other gases which can be useful here. These include, but are not limited to, films or thin sheets of: pure palladium, Pd-Ag/PSS or palladium alloys; silicon; polydimethylsiloxane; ion-transport cermet membrane composed of, for example, 60vol% BaCeO.
  • Membranes which are permeable to hydrogen could be used to enhance the effectiveness of the sensors described herein, by allowing hydrogen to reach the sensor, but preventing oxidization of the palladium clusters, or preventing poisoning of the sensor by other gases such as H 2 S or SO 2 which would not be able to penetrate the membrane.
  • a thin layer deposited on top of the cluster film may reduce the response time of the sensor.
  • a small canister and a thin membrane would allow faster equilibration of the hydrogen pressure.
  • the canister could contain material intended to remove oxygen or a desiccant, as well as a variety of other sensors for other gases.
  • the basic sensor of the invention comprise a film of clusters deposited between a pair of contacts.
  • a preferred embodiment (illustrated in Figure 31) comprises several films of particles deposited between several pairs of contacts.
  • the sensors are fabricated on
  • Si wafer substrates which enable many devices to be produced simultaneously and then diced up and packaged in such a way that they can simply be inserted into a socket on (for example) a printed circuit board within a hand held electronic control module.
  • percolating cluster films described in this application are intended primarily to be used as hydrogen sensors, however the methodology and devices described here could be used for a variety of alternative sensors (for both liquid and gaseous analytes).
  • each percolated film is arranged into a basic Wheatstone bridge.
  • the contact geometry of the contacts needs to be adjusted to accommodate 4 pairs of contacts, but all four percolating films can be deposited at the same time.
  • two opposing films are covered with a hydrogen impermeable layer. The resistance of these films will not depend on the outside hydrogen pressure; however, this resistance will still depend on the temperature. When no hydrogen is present, this bridge will remain balanced independent of the temperature. This is ideal for alarm sensors, which should not give false positives under changing temperature conditions.
  • An additional method of preventing a response of the sensor to a change in ambient temperature is to provide a temperature stabilised system consisting of a temperature sensor, a heater, and feedback electronics.
  • the hydrogen sensors discussed in this section consist of a palladium cluster film in between two contact pads, typically supported on a silicon substrate or silicon substrate coated with a thin layer of SiN or SiO x .
  • a later section describes sensors fabricated on substrates which have an additional film of Au islands.
  • the substrate for the contacts is a flat, square silicon piece cut out of a standard 0.55 mm thick wafer with a 200 nm silicon-oxide layer on top to provide a non-conducting and very flat surface.
  • the first step in the process is to clean the substrates through a standard rinsing procedure using acetone, then methanol and finally IPA.
  • Contact pads are formed on the substrate by thermal evaporation of 5 nm NiCr (80% Ni and 20% Cr) followed by 50 nm of Au through a shadow mask covering the area where no metal should be deposited. Thus two contacts, 3 mm wide and separated about 100 ⁇ m, are created. Au is chosen as it is readily available and NiCr is necessary to improve the adhesion to the silicon-oxide. This simple contact geometry and fabrication procedure is adequate for the present sensors, but we note that many more sophisticated lithographic procedures can be used to produce contacts of smaller dimensions, or of other geometries.
  • the wafer is diced into 1 cm 2 samples.
  • a thin PMMA polymer layer is spun on top. This layer is removed after the dicing using a standard cleaning procedure. Note that in commercial production it is expected that the contacts would be scaled down to allow the substrate to be diced into ⁇ 1 mm 2 pieces.
  • the general cluster deposition method is already described in [9, 12].
  • the clusters are prepared using a magnetron sputter cluster source, which consists of a 300mm long, liquid nitrogen or water cooled tube with an inner diameter of 95mm.
  • a Pd sputter target is installed at the front of a water cooled head mounted on a translatable arm inside the tube.
  • a voltage of around -300V is applied to the target while a grounded stainless steel shield at a distance of 0.5mm from the target acts as cathode.
  • cluster size can be varied between 1-15nm, for example, by changing the distance between the sputter target and the nozzle, by changing the argon pressure in the source, by introducing helium together with the argon or by changing the temperature of the source. This is illustrated in Figure 3 where two cluster size distributions are plotted for two different mixtures of argon and helium in the source. Generally smaller clusters are produced when helium is added.
  • the average cluster size deposited on this particular sample can be estimated to be around 3.5 - 4 nm. This estimate is consistent with the time of flight mass spectrometry data depicted in Figure 3.
  • the change of resistance upon hydrogen exposure is due to the efficient hydrogen absorption of Pd and its effect on the clusters in the film. As the clusters absorb hydrogen they expand and come into contact with neighbouring clusters. This will increase the number of conduction paths between the contact pads resulting in a lower resistance.
  • the cluster-cluster contact may, however, also lead to an irreversible coalescence of clusters. Coalescence may either result in formation of large islands with gaps in-between, and hence a breaking of conduction paths for coverage below p c or it might result in a more solid set of connections between the coalesced clusters and therefore a network with very low resistance. Neither of these effects are reversible and it is hence desirable to balance them out by depositing films with coverage between these two regimes, see Figure 26, where the resistance change upon hydrogen exposure is due to a reversible cluster expansion that is not followed by coalescence.
  • Figures 10 and 11 depict SEM pictures of cluster films at two different coverages. Both films have been exposed to hydrogen and the coverage after deposition has been estimated to be 0.67 and 0.77 respectively, i.e. slightly below and above p c .
  • the resolution is not high enough to see individual clusters, or to make out continuous paths between the contacts, but it can be seen that the clusters aggregate into 'islands' with typical diameters of 20 to 40 nm and it is possible to recognise larger irregular structures with dimensions at least up to several 100 nm in the film with higher coverage. The larger structures are less prominent on the film produced with a lower coverage. This is in good agreement with the scenario described above for the first hydrogen exposure. It should also be mentioned that the resistance increased by four orders of magnitude for the low coverage film while it decreased by two orders of magnitude for the film with higher coverage upon the first hydrogen exposure.
  • Figures 23 and 24 show the temperature dependence of the resistance of a typical sensor (for which the resistance had previously increased after the initial hydrogen exposure).
  • the cluster size was around 3.5nm for this particular sensor, see Figure 3 for size distribution.
  • Figure 24 therefore shows that the temperature dependence of the sensors described herein is consistent with tunnelling. Also characteristic for tunnelling conduction is a non-linear dependence of the current through the film on the voltage over the film. Figure 29 illustrates precisely such a nonlinear dependence.
  • the sensors described in this section are percolating-tunnelling type sensors i.e. they exhibit elements, such as the dependence of film properties on surface coverage, characteristic of percolation and other characteristics, such as resistance temperature behaviour, characteristic of tunnelling.
  • the structure of the sensor may be visualised schematically as in figure 16.
  • Figure 30 shows the temperature dependence of a cluster layer for which the resistance decreased strongly after the initial hydrogen exposure, resulting in a device with low resistance and a response to hydrogen far smaller than typical sensors with high resistances.
  • the resistance of the films shown in Figure 30 increases with increasing temperature, which indicates that the main conduction mechanism is not tunnelling conduction, i.e. this sensor exhibit conduction behaviour typical of most metallic materials.
  • Such films are much less sensitive than films of which the resistance increases after the initial hydrogen exposure.
  • the examples presented below all relate to cluster films for which the resistance increased after the initial hydrogen exposure and which exhibit tunnelling conduction.
  • the response of a similar film can be seen in Figure 5 for two hydrogen exposures at two different pressures.
  • the response time can be estimated, from the exponential edges on the response waveforms, to be around ten seconds which is considerably faster than the response of a very thick Pd cluster film, with coverage many time larger than the percolation threshold, as shown in Figure 6.
  • the increase in sensor resistance for the latter film (to be contrasted with the decrease in sensor resistance in Figure 5) is however due to the increased resistivity of bulk Pd and not due to the expansion and contraction of clusters, i.e. the response is dominated by metallic conduction and this is not a percolating tunnelling type sensor.
  • the response in Figure 6 is similar to commercial Pd based hydrogen sensors of the prior art based on thin films of Pd.
  • the comparison between the cluster sensor and the thick film sensor also shows that the sensitivity differs by almost an order of magnitude between these types of sensors.
  • the cluster film sensors are hence more sensitive and respond significantly faster to hydrogen exposure.
  • Figure 7 shows the resistance, normalized to the resistance in the absence of hydrogen (R 0 ), as a function of partial hydrogen pressure for two films with different R 0 values.
  • the relative change is virtually independent of the base resistance R 0 . This allows us to infer that as long as the coverage is not too large allowing bulk properties to dominate or too low with no conduction paths between the electrodes even in the presence of hydrogen, the cluster films may function as hydrogen sensors with similar relative response.
  • the sample preparation procedure is identical to that of the sensor on the unmodified silicon surface. The only difference is that the substrate is covered with a gold island film after the gold contacts have been realized and before the samples are diced.
  • the substrate surface between the contacts is covered with small gold islands by thermal evaporation of a very thin gold layer, which rather than forming a homogeneous thin film prefer to form a series of isolated islands as shown in Figure 13 which is a scanning electron micrograph picture of a gold island film with mean thickness 2nm.
  • Figure 18 the resistance of a gold island film is shown as a function of effective gold layer thickness. The exponential change in resistance with increasing mean gold layer thickness is due to a steady increase in mean island size and consequent decrease in mean island separation (tunnelling conductance is expected to vary exponentially with the width of the tunnel barrier).
  • Cluster deposition The procedure for cluster deposition is identical to that of the sensor on the unmodified silicon surface. In this case however, when clusters are deposited between the contacts, the tunnelling resistance reduces exponentially with time (dashed line in Figure 21). This allows in situ control of the cluster surface coverage for coverages well below the percolation threshold. For the sensor treated in this example, the surface coverage is less than the percolation threshold, contrary to the sensor fabricated on an unmodified silicon substrate, as treated in the previous example, where the surface coverage was around the percolation threshold.
  • FIG 25 the resistance as a function of time for the first hydrogen load is depicted for two Au island sensors.
  • FIG 22 the resistances of a series of sensors before and after the first hydrogen load are depicted.
  • the open circles represent sensors that respond irreversibly to exposure to hydrogen and the closed circles refer to sensors that respond reversibly.
  • the initial sensor resistance after cluster deposition is less critical for obtaining reversible sensors for sensors fabricated on a silicon substrate covered with gold islands, than for sensors fabricated on an unmodified silicon substrate
  • This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

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Abstract

L'invention concerne un dispositif de capteur d'hydrogène constitué d'un film ou de plusieurs films non contigus d'agrégats de l'échelle du nanomètre, situé entre au moins deux contacts d'un substrat. Ce film non contigu réagit à la présence du gaz hydrogène par une modification de résistivité électrique entre les contacts provoquée par une conduction, selon une conduction ohmique à l'intérieur du film, entre les deux contacts; selon une conduction par effet tunnel à l'intérieur du film, entre les deux contacts; ou selon une combinaison de conduction ohmique et de conduction par effet tunnel, à l'intérieur du film, entre les deux contacts. L'invention concerne également une méthode de préparation d'un tel capteur.
PCT/NZ2006/000101 2005-05-09 2006-05-09 Capteurs d'hydrogene et leurs methodes de fabrication WO2006121349A1 (fr)

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Cited By (7)

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WO2008143534A1 (fr) * 2007-05-22 2008-11-27 Andreas Lassesson Procédé de préparation de capteurs de fluides d'amas d'oxyde métallique en film mince
EP2175265A1 (fr) * 2008-10-08 2010-04-14 IEE International Electronics & Engineering S.A.R.L. Capteur d'hydrogène et son procédé de fabrication
WO2011011828A1 (fr) * 2009-07-29 2011-02-03 The University Of Western Australia Dispositif et procédés de fabrication et d’utilisation associés
CN102495045A (zh) * 2011-11-07 2012-06-13 华中科技大学 一种光纤氢气传感器用氢敏材料及其制备方法
CN101482528B (zh) * 2009-01-23 2013-01-02 南京大学 一种可集成的密集纳米颗粒单层膜氢气传感器的制备方法
CN110945353A (zh) * 2017-06-13 2020-03-31 通用电气公司 用阻抗式气体感测器的溶解气体分析
CN113155904A (zh) * 2021-02-02 2021-07-23 浙江工业大学 一种用于空气环境中的高灵敏氢气传感器及其制备方法

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WO2003008954A1 (fr) * 2001-07-20 2003-01-30 The Regents Of The University Of California Sonde de detection du gaz hydrogene
WO2004020978A2 (fr) * 2002-08-30 2004-03-11 Nano-Proprietary, Inc. Formation de nanofils metalliques s'utilisant comme detecteurs d'hydrogene a plage variable
WO2005001420A2 (fr) * 2003-06-03 2005-01-06 Nano-Proprietary, Inc. Procede et appareil permettant de detecter le gaz hydrogene
US20050155858A1 (en) * 2002-08-30 2005-07-21 Nano-Proprietary, Inc. Continuous-range hydrogen sensors
US20050224360A1 (en) * 2004-04-02 2005-10-13 The Penn Research Foundation Titania nanotube arrays for use as sensors and method of producing
US7047792B1 (en) * 2003-07-07 2006-05-23 University Of South Florida Surface acoustic wave hydrogen sensor
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WO2003008954A1 (fr) * 2001-07-20 2003-01-30 The Regents Of The University Of California Sonde de detection du gaz hydrogene
WO2004020978A2 (fr) * 2002-08-30 2004-03-11 Nano-Proprietary, Inc. Formation de nanofils metalliques s'utilisant comme detecteurs d'hydrogene a plage variable
US20050155858A1 (en) * 2002-08-30 2005-07-21 Nano-Proprietary, Inc. Continuous-range hydrogen sensors
WO2005001420A2 (fr) * 2003-06-03 2005-01-06 Nano-Proprietary, Inc. Procede et appareil permettant de detecter le gaz hydrogene
US7047792B1 (en) * 2003-07-07 2006-05-23 University Of South Florida Surface acoustic wave hydrogen sensor
US20050224360A1 (en) * 2004-04-02 2005-10-13 The Penn Research Foundation Titania nanotube arrays for use as sensors and method of producing
US20060112756A1 (en) * 2004-12-01 2006-06-01 The University Of Chicago Ultrafast and ultrasensitive hydrogen sensors based on self-assembly monolayer promoted 2-dimensional palladium nanoclusters

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008143534A1 (fr) * 2007-05-22 2008-11-27 Andreas Lassesson Procédé de préparation de capteurs de fluides d'amas d'oxyde métallique en film mince
EP2175265A1 (fr) * 2008-10-08 2010-04-14 IEE International Electronics & Engineering S.A.R.L. Capteur d'hydrogène et son procédé de fabrication
CN101482528B (zh) * 2009-01-23 2013-01-02 南京大学 一种可集成的密集纳米颗粒单层膜氢气传感器的制备方法
WO2011011828A1 (fr) * 2009-07-29 2011-02-03 The University Of Western Australia Dispositif et procédés de fabrication et d’utilisation associés
CN102495045A (zh) * 2011-11-07 2012-06-13 华中科技大学 一种光纤氢气传感器用氢敏材料及其制备方法
CN110945353A (zh) * 2017-06-13 2020-03-31 通用电气公司 用阻抗式气体感测器的溶解气体分析
CN113155904A (zh) * 2021-02-02 2021-07-23 浙江工业大学 一种用于空气环境中的高灵敏氢气传感器及其制备方法
CN113155904B (zh) * 2021-02-02 2023-06-20 浙江工业大学 一种用于空气环境中的高灵敏氢气传感器及其制备方法

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