SI23582A - An array smell sensor based on the measurement of the junction resistance of nanowires with different metals - Google Patents
An array smell sensor based on the measurement of the junction resistance of nanowires with different metals Download PDFInfo
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- G—PHYSICS
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- 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
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- G01N27/127—Composition of the body, e.g. the composition of its sensitive layer comprising nanoparticles
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- B82Y15/00—Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
Abstract
Description
Sistem senzorjev za vonjave delujoč na osnovi meritev impedance stičišč nanožic z različnimi kovinamiOdor sensor system based on impedance measurements of junctions of nanowires with different metals
Predmet tega izuma je selektiven sistem senzorjev vonjav, imenovan elektronski nos, ki deluje tako, da zazna spremembe impedance v stičiščih nanožic in kovin. Različni elementi sistema so narejeni iz različnih kovin, tako imajo nanožice na vsakem elementu kontakt z drugo kovino. Ko v stičiščih nanožic in kovin pride do kapilarne kondenzacije analitov, se impedanca stičišč spremeni. Adsorpcijske lastnosti različnih analitov so različne na različnih kovinskih površinah, zaradi česar se vsak element drugače odziva na določen analit. To ustvarja podlago za večelementni senzorski sistem, narejen iz različnih kontaktnih materialov, od katerih se vsak drugače odziva na določen analit. Sposobnost prepoznavanja dobimo z analiziranjem - ob uporabi primerne programske opreme - odziva celotnega sistema in njegovo primerjavo z referenčnimi odzivi za posamezne analite.The object of the present invention is a selective odor sensor system called the electronic nose, which operates to detect impedance changes in the junctions of nanowires and metals. Different elements of the system are made of different metals, so the nanowires on each element have contact with another metal. When capillary condensation of the analytes occurs at the junctions of nanowires and metals, the impedance of the junctions changes. The adsorption properties of different analytes are different on different metal surfaces, which makes each element react differently to a particular analyte. This forms the basis for a multi-element sensor system made of different contact materials, each of which responds differently to a particular analyte. The ability to identify is obtained by analyzing - using appropriate software - the response of the whole system and comparing it with the reference responses for individual analytes.
Ozadje izumaBACKGROUND OF THE INVENTION
Sedanji najsodobnejši kemični senzorji uporabljajo detektorje površinskih akustičnih valov (SAW), detektorje iz polimernih nanokompozitov, naprave s kremenčevo mikrotehtnico, naprave za zaznavanje kovinskih oksidov (MOS) ter okrašene ali funkcionalizirane nanožice oziroma nanocevke. Večje naprave za določitev molekularne mase analita uporabljajo masno spektroskopijo. Za razpoznavo detekcijo je nujna uporaba sistema senzorjev, kot jih imamo v primeru senzorjev iz polimernih nanokompozitov. Senzorji iz polimernih nanokompozitov temeljijo na difuziji molekul analita v velik polimer, kar spremeni upor posameznega elementa, ob tem pa se kot prevodno polnilo običajno uporablja ogljikov prah, da z njim povečamo prevodnost senzorja.Current state-of-the-art chemical sensors use surface acoustic wave (SAW) detectors, polymer nanocomposite detectors, silica microtechnology devices, metal oxide sensing (MOS) devices, and ornate or functionalized nanotubes or nanotubes. Larger devices for molecular weight determination of the analyte use mass spectroscopy. For detection, it is essential to use a sensor system as we have in the case of sensors made of polymer nanocomposites. Sensors made of polymer nanocomposites are based on the diffusion of analyte molecules into a large polymer, which alters the resistance of a single element, using carbon dust as a conductive filler to increase the conductivity of the sensor.
Eden od možnih pristopov k izboljšanju občutljivosti zaznave je uporaba nanožic ali nanocevk v funkciji senzorskih elementov. Visoka razmerja med površino in prostornino, značilna za te nanostrukture omogočijo, da se njihove električneOne possible approach to improving sensing sensitivity is to use nanowires or nanotubes as a function of sensing elements. The high surface-to-volume ratios inherent in these nanostructures make it possible for their nanostructures to be electric
-2lastnosti spreminjajo ob prisotnosti molekul, ki so adsorbirane na njihovih površinah in ob kontaktih med nanožicami. Dejanski senzorski mehanizmi pa so lahko zelo različni. Penner in sodelavci (E. C. VValter, F. Faview in R. M. Penner, Anal. Chem. vol. 74, str. 1546 (2002); F. Favier, E. C. VValter, M. P. Zach, T. Benter in R. M. Penner, Science vol. 293, str. 2227 (2001)) so izdelali vodikov senzor, ki uporablja Pd nanožice nameščene na površini tankega polimernega filma. Vsaka nanožica je vzdolž svoje površine vsebovala veliko prelomnih stičišč. Reža med njimi se je spremenila, ko je bil vodikov plin adsorbiran v Pd kristalno mrežo, upor teh nanožic pa je bil izrazito odvisen od koncentracije plina. V drugih eksperimentih so Cui in sodelavci modificirali površine polprevodnih nanožic in jih uporabili kot visoko občutljive senzorje za zaznavanje vrednosti pH in bioloških vrst v realnem času (Y. Cui, Q. VVei, H. Park in C. M. Lieber, Science vol. 293, str. 1289 (2001)). Ta mehanizem je bil opisan v luči spremembe površinskega naboja, ki sta jo povzročila protonacija in deprotonacija. Nedavno pa so Law in sodelavci izdelali fotokemijski NO2 senzor delujoč pri sobni temperaturi in temelječ na enojni nanožici ali enojnem nanotraku enokristalnih oksidov (M. Law, H. King, F. Kirn, B. Messer in P. Yang, Angew. Chem. Int. Ed. vol. 41, str. 2405 (2002)), kjer dušikov dioksid deluje kot adsorbirana snov, ki na površinah SnO2 lovi elektrone in ga lahko nadziramo z merjenjem električne prevodnosti materiala.-2 properties change in the presence of molecules adsorbed on their surfaces and at the contacts between the nanowires. The actual sensing mechanisms can be very different. Penner et al. (EC VValter, F. Faview and R. M. Penner, Anal. Chem. Vol. 74, p. 1546 (2002); F. Favier, E. C. Valter, M. P. Zach, T. Benter, and R. M. Penner, Science vol. 293 , pp. 2227 (2001)) have produced a hydrogen sensor that uses Pd nanowires mounted on the surface of a thin polymer film. Each nanowire contained many breakpoints along its surface. The gap between them changed when hydrogen gas was adsorbed into the Pd crystal lattice, and the resistance of these nanowires was markedly dependent on the gas concentration. In other experiments, Cui and colleagues modified the surfaces of semiconductor nanowires and used them as highly sensitive sensors for real-time pH and biological species sensing (Y. Cui, Q. VVei, H. Park, and CM Lieber, Science vol. 293, p. 1289 (2001). This mechanism has been described in light of the change in surface charge caused by protonation and deprotonation. Recently, however, Law and co-workers produced a photochemical NO 2 sensor operating at room temperature and based on a single nanowire or single nanotube of single crystalline oxides (M. Law, H. King, F. Kirn, B. Messer, and P. Yang, Angew. Chem. 41, pp. 2405 (2002), where nitrogen dioxide acts as an adsorbed substance that traps electrons on SnO 2 surfaces and can be controlled by measuring the electrical conductivity of the material.
Da bi dosegli senzorsko prepoznavanje plinov in hlapov, je treba izdelati sistem različnih senzorjev, ki se različno odzivajo na različne analite, zato je pomembno odkrivati nove vrste senzorskih materialov. Li in sodelavci so pokazali, da kemisorbirane molekule lahko zaznamo tudi kot spremembe v prevodnosti zlatih nanožic (C. Z. Li et al., Appl. Phys. Lett. vol. 76, str. 1333 (2000)). Zgodnje raziskave ogljikovih nanocevk z enojno steno (SVVCNTs) (J. Kong, et al., Science vol. 87, str. 622 (2000), P. G. Collins et al., Science, vol. 287, str. 1801, (2000), Bekyanova et al., J. Phys. Chem. B 108, 19717 (2004), T. Someya et al., Nano Lett. 3, 877, (2003), J. Li et al., Nano Lett. vol. 3, str. 929 (2003), S. Snow, F. K. Perkins, E. H. Houser, Science, vol. 307, str. 1942 (2005)) so pokazale na spremembe v prevodnosti, ki nastanejo kot odziv na prisotnost molekul, adsorbiranih na površini ogljikovih nanocevk z enojno steno. Uporabljene so bile različne sheme zaznavanja, na primer zaznavanje upora ali konfiguracije tranzistorjev z učinkom polja (W. U. Wang et al.,In order to achieve sensory recognition of gases and vapors, it is necessary to create a system of different sensors that respond differently to different analytes, so it is important to discover new types of sensor materials. Li and co-workers have shown that chemisorbed molecules can also be detected as changes in the conductivity of gold nanowires (C. Z. Li et al., Appl. Phys. Lett. Vol. 76, p. 1333 (2000)). Early Single Wall Carbon Nanotube Research (SVVCNTs) (J. Kong, et al., Science vol. 87, p. 622 (2000), PG Collins et al., Science, vol. 287, p. 1801, (2000) , Bekyanova et al., J. Phys Chem Chem B 108, 19717 (2004), T. Someya et al., Nano Lett 3, 877, (2003), J. Li et al., Nano Lett vol. 3, pp. 929 (2003), S. Snow, FK Perkins, EH Houser, Science, vol. 307, pp. 1942 (2005) showed changes in conductivity that occur in response to the presence of molecules adsorbed on the surface single wall carbon nanotubes. Different detection schemes have been used, such as resistor detection or field effect transistor configurations (W. U. Wang et al.
-3PNAS vol. 102, str, 3208 (2005), A. Star et al., Nano Letters vol. 3, str. 459 (2003), ibid., Nano letters vol. 3, str. 1421 (2003) 3, M. Law, H. King, F. Kirn, B. Messer in P. Yang, Angew, Chem. Int.Ed. vol. 41, str. 2405 (2002)). Snow in Perkins (E. S. Snow in F. K. Perkins, Nano Letters, vol. 5, str. 2414 (2005), Mark C. Lonergan et al., Chem Mater, 8, 2298 (1996), Frederic Favier et. al., Science, vol. 293, str. 2227 (2001), Xingjiu Huang et.al., Nanotechnology vol. 15, str. 1284 (2004), Y. S. Kim et.al., Sensors and Actuators B vol. 108, str. 285 (2005)) sta združila meritve prevodnosti in kapacitivnosti in s tem ugotovila posebne lastnosti adsorbiranih molekul. Nedavno so bile opisane podrobnejše meritve senzorja hlapov, opravljene na nanožičnih filmih iz spojine Li2Mo6Se6 (X. Oi in F. E. Osterloh, J. Am. Chem. Soc. vol. 127, str. 7666 (2005), X. Oi et al., Annal. Chem. vol. 78, str. 1306 (2006)). Ugotovljeno je bilo, da se je upor povečal ob izpostavljenosti različnim analitom, na primer heksanu, THF, etanolu in DMSO. Povečan upor naj bi bil posledica spremembe v kontaktih med posameznimi svežnji, ki jo povzroči kondenzacija molekul analitov med nanožičnimi svežnji, saj ta zmanjšuje preskakovanje (tuneliranje) med posameznimi svežnji. Žal je spojina Li2 Mo6 Se6 občutljiva na kisik, kar omejuje njeno uporabnost pri izdelavi senzorjev.-3PNAS vol. 102, pp. 3208 (2005), A. Star et al., Nano Letters vol. 3, p. 459 (2003), ibid., Nano letters vol. 3, p. 1421 (2003) 3, M. Law, H. King, F. Kirn, B. Messer, and P. Yang, Angew, Chem. Int.Ed. vol. 41, p. 2405 (2002). Snow and Perkins (ES Snow and FK Perkins, Nano Letters, vol. 5, p. 2414 (2005), Mark C. Lonergan et al., Chem Mater, 8, 2298 (1996), Frederic Favier et al., Science , vol 293, p 2227 (2001), Xingjiu Huang et.al., Nanotechnology vol 15, p 1284 (2004), YS Kim et.al., Sensors and Actuators B vol 108, p 285 ( 2005)) combined the conductivity and capacitance measurements to determine the specific properties of the adsorbed molecules. More recently, more detailed measurements of vapor sensor measurements made on nanowire films of Li 2 Mo 6 Se6 compound (X. Oi and FE Osterloh, J. Am. Chem. Soc. Vol. 127, p. 7666 (2005), X. Oi et al., Annal. Chem. vol. 78, p. 1306 (2006). Resistance was found to increase upon exposure to various analytes such as hexane, THF, ethanol and DMSO. The increased resistance is due to the change in contacts between the individual bundles caused by the condensation of the analyte molecules between the nanowire bundles, since this reduces the tunneling between the bundles. Unfortunately, the Li 2 Mo 6 Se 6 compound is oxygen sensitive, which limits its usefulness in the manufacture of sensors.
Alternativni material, ki ima želene lastnosti, je Mo6Sg.xlx (MoSI) (D. Vrbanič et al., Nanotechnology vol. 15, str. 635 (2004)). Njegove elektronske lastnosti so podobne lastnostim spojine Li2Mo6Se6, a je tudi stabilen na zraku do 200 °C in kemijsko inerten. Ta material je prevoden (B. Berčič et al., Applied Phys. Lett. vol. 88, str.An alternative material having the desired properties is Mo6Sg. x lx (MoSI) (D. Vrbanič et al., Nanotechnology vol. 15, p. 635 (2004)). Its electronic properties are similar to those of Li 2 Mo 6 Se 6 , but it is also stable in air up to 200 ° C and chemically inert. This material is conductive (B. Berčič et al., Applied Phys. Lett. Vol. 88, p.
173103 (2006)), in je lahko narejen v obliki svežnjev različnih premerov, ki jih ustvarimo s spreminjanjem disperzije (Mihailovič, Prog. Mat. Sci. vol. 54, str. 309, (2009)) in pogojev rasti (Dvorsek et al., J. Appl Phys., vol. 102, str. 114308 (2007)).173103 (2006)), and can be made in the form of bundles of different diameters created by varying dispersion (Mihailovič, Prog. Mat. Sci. Vol. 54, p. 309, (2009)) and growth conditions (Dvorsek et al ., J. Appl Phys., Vol. 102, pp. 114308 (2007).
Dokazano je, da je primeren za uporabo v dvokontaktnem senzorju upora zasnovanem v obliki mreže (B. Berčič et al., Applied Phys. Lett. 88, 173103 (2006), M. Devetak et al., Chem. Mater. vol. 20, str. 1773-177 (2008)).It is proven to be suitable for use in a two-pin grid-shaped resistance sensor (B. Berčič et al., Applied Phys. Lett. 88, 173103 (2006), M. Devetak et al., Chem. Mater. Vol. 20 , pp. 1773-177 (2008).
Pomanjkljivosti sedanjih senzorjev so relativno omejena selektivnost, dolg odzivni čas, na katerega vpliva difuzija analita, težave z obnovljivostjo rezultatov in majhen operativni razpon z ozirom na koncentracijo, nasičenostjo, neprimernostjo za masovno proizvodnjo ter občutljivostjo na zrak. Nova iznajdba rešuje navedeneThe disadvantages of the present sensors are the relatively limited selectivity, the long response time affected by the diffusion of the analyte, the problems with reproducibility of the results and the small operating range with respect to concentration, saturation, unsuitability for mass production and sensitivity to air. The new invention solves the above
-4težave z oblikovanjem senzorskega sistema z več elementi, ki nudi rekognitivni odziv, konstrukcijo, ki omogoča razširitev, enostavnost izdelave, majhno porabo energije, ter visoko in specifično odzivnost na mnoge različne analite.-4 Problems with the design of a multi-element sensor system that offers a cognitive response, a design that allows for expansion, ease of manufacture, low energy consumption, and high and specific responsiveness to many different analytes.
Opis izumaDescription of the invention
Opis izuma dopolnjujejo slike, ki predstavljajo naslednje:The description of the invention is supplemented by figures representing the following:
Slika 1. Shematičen prikaz posameznega senzorskega elementa, sestavljenega iz nanožice 6, ki premošča režo 8 med elektrodama 4.Figure 1. Schematic representation of a single sensing element consisting of a nanowire 6 bridging a gap 8 between the electrodes 4.
Slika 2. Shematičen prikaz posameznega elementa senzorskega vezja, sestavljenega iz elektrod 4 in nanožic 6, ki premoščajo režo 8 med elektrodama 4.Figure 2. Schematic representation of a single element of the sensor circuit consisting of electrodes 4 and nanowires 6 bridging the gap 8 between electrodes 4.
Slika 3. Shematičen prikaz večelementnega senzorja.Figure 3. Schematic representation of a multi-element sensor.
Slika 4. Normalizirani odziv, tj., spremenjen upor posameznega senzorja na različne analite 1 pri različnih koncentracijah, merjenih v ppm.Figure 4. Normalized response, i.e., altered resistivity of a single sensor to different analytes 1 at different concentrations measured in ppm.
Slika 5. Odziv štirih elementov senzorja z elektrodami Ni 9, Pd 10, Pt 11 in Ti 12, ki jih, v vseh primerih, premoščajo nanožice 6, na aceton, 2-butanol, metanol in vodo.Figure 5. Response of four sensor elements with Ni 9, Pd 10, Pt 11 and Ti 12 electrodes, which, in all cases, are bridged by nanowires 6, to acetone, 2-butanol, methanol and water.
Problem prepoznavanja različnih analitov 1, ki se nahajajo posamično ali sočasno v parni fazi, je rešen s pomočjo večelementnega senzorskega niza, v katerem se vsak element različno odziva na vsakega od prisotnih analitov 1 in kjer je analit 1 prepoznan z merjenjem in analizo odziva celotnega senzorskega niza. V tem nizu vsako senzorsko vezje sestoji iz kompleta interdigitalnih elektrod 4, ki jih ločuje majhna reža 8. Nanožice 6 so nameščene nad elektrodami 4, tako da tvorijo električni kontakt. Pri vsakem elementu področje kontakta med nanožico 6 in kovinsko elektrodo 4, ki se pojavlja kot linija kontaktnih točk - opredeljeno kot področje kapilarne kondenzacije 5, ki se odslej imenuje PKK 5 in je predstavljeno v Sliki 1 - ob prisotnosti molekul analita 1 spremeni impedanco vezja.The problem of identifying different analytes 1, individually or simultaneously in the vapor phase, is solved by means of a multi-element sensor array, in which each element responds differently to each of the analytes 1 present, and where analyte 1 is recognized by measuring and analyzing the response of the entire sensory series. In this set, each sensor circuit consists of a set of interdigital electrodes 4 separated by a small slot 8. Nanowires 6 are positioned above the electrodes 4 to form an electrical contact. For each element, the contact area between the nanowire 6 and the metal electrode 4, which appears as a contact point line - defined as the area of capillary condensation 5, henceforth referred to as PKK 5 and presented in Figure 1 - changes the impedance of the circuit in the presence of analyte 1 molecules.
-5Nanožica 6 je lahko sveženj Mo6S9-xlx, pri katerem je 3 < x < 6, ali kakšen drug anorganski ali organski sveženj nanožic, sveženj nanocevk, ali polimerni sveženj ali vrvica. Nanožice 6 so lahko izdelane iz tanjših polimerov ali molekularnih žic v neurejeni obliki; lahko so tudi kristalinične, vse pa so odslej označene kot nanožice 6.-5Nose 6 can be a stack of Mo 6 S9-xl x with 3 <x <6, or some other inorganic or organic bundle of nanowires, a bundle of nanotubes, or a polymer bundle or string. Nanoparticles 6 can be made of thin polymers or molecular wires in a disordered form; they may also be crystalline but are now referred to as nanowires 6.
Elektrode so narejene iz različnih prevodnih materialov. Vsak element je sestavljen iz dvokontaktnih elektrod 4, ki ju povezuje nanožica 6. Materiali za elektrode 4 so lahko kovine, na primer Ti, Pd, Ni, Au, Mo, Ag, Pt ali drugi prevodni materiali, na primer oksid indija in kositra InSnO (ITO), materiali na osnovi ogljika, prevodni polimeri, sintetične kovine, prevodni kompoziti, dopirani polprevodniki in organski materiali ter drugi prevodni materiali, na primer ogljikov prah, nanešeni s postopki brizgalnega tiskanja, sitotiska, izparevanja, pršenja, galvanizacije ali z drugimi postopki. Občutljivost vsakega elementa na različne analite 1 je drugačna in tako omogoča selektivno prepoznavanje analitov 1. Kontaktna voda 2 sta prevlečena s kontaktno pasto 3, da imata lahko dober električen kontakt z elektrodama 4. Elektrodi 4 sta nanešeni na substrat 7, na primer na oksidiran silicijev substrat, pa tudi na plastično, stekleno ali aluminijasto podlago.The electrodes are made of various conductive materials. Each element consists of two-pin electrodes 4 connected by nanowire 6. Electrode materials 4 may be metals, such as Ti, Pd, Ni, Au, Mo, Ag, Pt, or other conductive materials, such as indium oxide and tin InSnO. (ITO), carbon-based materials, conductive polymers, synthetic metals, conductive composites, doped semiconductors and organic materials and other conductive materials, such as carbon dust, deposited by inkjet, screen printing, evaporation, spray, electroplating or other processes . The sensitivity of each element to different analytes 1 is different and thus allows selective recognition of analyte 1. Contact water 2 is coated with contact paste 3 to have good electrical contact with electrodes 4. The electrodes 4 are applied to substrate 7, for example, oxidized silicon. substrate as well as plastic, glass or aluminum substrate.
Število molekul analita 1 v PKK 5 vsakega elementa je vezano na ambientalni parni tlak analital. Sprememba impedance vsakega elementa je vezana na število mulekul analita 1 v PKK 5. Impedanca je torej direktno vezana na parni tlak analitov 1.The number of analyte 1 molecules in PKK 5 of each element is related to the ambient vapor pressure of the analyte. The change in impedance of each element is related to the number of analyte 1 molecules in PKK 5. The impedance is therefore directly related to the vapor pressure of analyte 1.
Sposobnosti zaznavanja posameznih senzorskih elementov so različne zaradi katerekoli od spodaj naštetih lastnosti oziroma zaradi katerekoli kombinacije naštetih lastnosti (čeprav ne zgolj zaradi teh): adsorpcijski in desorpcijski koeficienti (fizisorpcija ali kemisorpcija) za molekule analitov 1 na materialu elektrode 4 ali na nanožicah 6, različna hrapavost elektrod 4 ali nanožic 6, različne delovne funkcije elektrod 4 in/ali nanožic 6, različna površinska napetost analitov 1 na elektrodah 4 ali na nanožicah 6.The sensing capabilities of the individual sensing elements are different due to any of the following properties, or any combination of the following (though not solely because of them): adsorption and desorption coefficients (physisorption or chemisorption) for analyte molecules 1 on electrode material 4 or on nanowires 6, different roughness of electrodes 4 or nanowires 6, different working functions of electrodes 4 and / or nanowires 6, different surface tension of analytes 1 on electrodes 4 or nanowires 6.
Tipični senzor uporablja 4 do 32 ali več elementov, od katerih je vsak narejen iz drugačne kombinacije kovine in nanožice.A typical sensor uses 4 to 32 or more elements, each made of a different combination of metal and nanowire.
-6Elektrodi 4 sta lahko naneseni na substrat 7 z galvanizacijo, pršenjem, izparevanjem, sitotiskom, brizgalnim tiskanjem v kombinaciji s fotolitografijo, lasersko litografijo, litografijo z elektronskim žarkom, itd. Da bi ustvarili različni kovinski elektrodi 4, ali spremenili njuni značilnosti, lahko obstoječima elektrodama z galvaniziranjem, z nanašanjem plasti atomov ali z drugo metodo dodamo vrhnji nanos.-6Electrodes 4 may be applied to substrate 7 by electroplating, spray, evaporation, screen printing, inkjet printing in combination with photolithography, laser lithography, electron beam lithography, etc. In order to create different metal electrodes 4, or to change their characteristics, the top electrode can be added to the existing electrodes by electroplating, depositing atoms or by another method.
Nanožice 6 so lahko posamično nanesene preko vsakega stičišča, ali pa je celotna površina prekrita z redko mrežo nanožic 6.Nanowires 6 may be individually applied at each junction, or the entire surface may be covered by a sparse web of nanowires 6.
V alternativni izvedbi so različne kovine elektrod nanesene na silicijev substrat 7 z izparevanjem skozi masko, nanožice 6 pa so nanesene iz raztopine s kapljičnim nanašanjem ali rotacijskim nanašanjem.In an alternative embodiment, the various electrode metals are applied to the silicon substrate 7 by evaporation through a mask, and the nanowires 6 are applied from the solution by drip deposition or rotational deposition.
Senzorski elektrodi 4 iz Slike 2 sta preko reže 8 lahko povezani z eno nanocevko ali z več nanocevkami, z nanožico ali nanožicami 6, s svežnjem ali z mrežo nanocevk ali nanožic 6, ter s svežnji nanocevk ali nanožic 6, ki z elektrodama ustvarijo redke električne kontakte. Kot material lahko uporabimo svežnje nanožic 6 z molekularno obliko MoSI, nanožice 6 in nanocevke različnih vrst, kadar so te prevodne ali polprevodne.The sensor electrodes 4 of Figure 2 can be connected via a slot 8 to a single nanotube or multiple nanotubes, a nanowire or nanowires 6, a bundle or a network of nanotubes or nanowires 6, and bundles of nanotubes or nanowires 6 that generate rare electrical electrodes contacts. As material, bundles of MoSI molecular nanoparticles 6, nanoparticles 6, and nanotubes of various types can be used when these are conductive or semiconductor.
V alternativni izvedbi je material nanožic 6 ovit ob elektrodah 4, s čimer se ustvari mehanski nanos tankega filma nanožic 6, ki nad režo 8 povezuje elektrodi.In an alternative embodiment, the material of the nanowires 6 is wrapped next to the electrodes 4, thereby creating a mechanical deposition of a thin film of nanowires 6 that connects the electrodes above the slot 8.
V drugi alternativni izvedbi so nanožice 6 ali nanocevke nanešene na področje reže 8, da povežejo elektrodi 4; nanos je izveden z uporabo dielektroforeze, ki pritegne nanožice ali nanocevke na področje kontaktov.In another alternative embodiment, nanowires 6 or nanotubes are applied to the region of the slot 8 to connect the electrodes 4; the application is carried out using dielectrophoresis, which attracts nanowires or nanotubes to the contact area.
V naslednji izvedbi so nanožice 6 napršene na elektrodi 4 in čez režo 8 z uporabo zračnega čopiča ali s sistemom ultrazvočnega pršenja.In another embodiment, the nanowires 6 are sprayed on the electrode 4 and across the slot 8 using an air brush or an ultrasonic spray system.
V drugačni izvedbi odziv vsakega senzorja v sistemu spremenimo z dodajanjem različnih molekularnih slojev v stičišča tuneliranja, na primer s prevlečenjem nanožic 6 s površinsko aktivno snovjo pred njihovim nanosom na kontakt. Na ta način lahko število različnih elementov bistveno naraste, s čimer se povečajo senzorske sposobnosti sistema senzorjev.In another embodiment, the response of each sensor in the system is altered by adding different molecular layers to the tunneling junctions, for example by coating nanowires 6 with a surfactant prior to their application to contact. In this way, the number of different elements can be substantially increased, thus enhancing the sensory capabilities of the sensor system.
• ·• ·
-7Lastnosti PKK 5 lahko spremenimo s prilagoditvijo hrapavosti elektrod, kar vpliva na občutljivost senzorja.-7 PKK 5 properties can be modified by adjusting the electrode roughness, which affects the sensitivity of the sensor.
Senzor deluje kot večelementni niz upornikov. Sprememba upora vsakega elementa nastane kot odziv na prisotnost molekul analitov 1. Odziv vsakega od elementov 912 je različen, ker vsak element uporablja drugačno kovinsko elektrodo 4, ki je v stiku z nanožico 6. Različne kovine imajo različne adsorpcijske in desorpcijske značilnosti površine, kar pomeni, da se lahko različni analiti 1 različno akumulirajo v stičiščih nanožic in kovine. Različne kovine imajo tudi različne delovne funkcije, kar vodi v različne značilnosti transfera elektronov med nanožicami 6 in kovinskima elektrodama 4 skozi analit 1.The sensor acts as a multi-element resistor array. The change in the resistance of each element occurs in response to the presence of analyte molecules 1. The response of each element 912 is different because each element uses a different metal electrode 4 that is in contact with the nanowire 6. Different metals have different adsorption and desorption characteristics of the surface, meaning , that different analytes 1 may accumulate differently at the junctions of nanowires and metals. Different metals also have different working functions, leading to different electron transfer characteristics between nanowires 6 and metal electrodes 4 through analyte 1.
Pri ponovljenem delovanju je morda potrebno kemosenzor regenerirati z odstranitvijo analita 1. To lahko naredimo s segrevanjem sensorja v inertnem plinu, vakuumu ali v aktivnem plinu. Segrevanje je lahko izvedeno tako, da skozi senzor spustimo električni tok, neprekinjeni ali pulziranj, ali da v bližini naprave uporabimo upornik ali optično napravo, na primer laser ali bliskovno luč.In the case of repeated operation, it may be necessary to regenerate the chemosensor by removing analyte 1. This can be done by heating the sensor in an inert gas, vacuum or in an active gas. Heating can be accomplished by dropping electrical current, continuous or pulsed through the sensor, or by using a resistor or optical device such as a laser or a flashlight near the device.
Specifične prednosti senzorja so:The specific advantages of the sensor are:
1. Zaznavni odziv je ustvarjen z izbiro različnih materialov za elektrode 4 in/ali nanožice 6, kar omogoči veliko število možnih senzorskih elementov, od katerih se vsak odziva drugače.1. A sensing response is created by selecting different materials for electrodes 4 and / or nanowires 6, allowing for a large number of possible sensing elements, each of which responds differently.
2. Razpon odzivov je večji kot pri perkolacijskih senzorjih.2. The response range is larger than that of percolation sensors.
3. Enostavno prilagodljiva velikost konstrukcije, ki temelji na rabi različnih kovinskih elektrod 4.3. Easily adjustable size of construction based on the use of different metal electrodes 4.
4. Enostavna izdelava multisenzorskega sistema.4. Easy design of multisensor system.
5. Posamični senzorji v sistemu so lahko zelo majhni.5. The individual sensors in the system can be very small.
6. Izjemno majhna disipacija energije.6. Extremely low energy dissipation.
• « • ·• «• ·
-87. Regeneracijo lahko izvedemo s segrevanjem substrata 7 ali tako, da skozi napravo pošljemo močan tok, ki povzroči izparevanje molekul v predelu stičišča.-87. Regeneration can be accomplished by heating the substrate 7 or by sending a strong current through the device that causes the molecules to evaporate in the junction region.
8. Odziv temelji na uporu, je enostavno evidentiran in analiziran z uporabo standardnih meritvenih tehnik.8. The response is resistance based, easily recorded and analyzed using standard measurement techniques.
9. Geometrija naprave je zelo prožna; kovinska elektroda 4 je lahko z različnimi tehnikami nanesena na različne substrate 7.9. The geometry of the device is very flexible; the metal electrode 4 can be applied to different substrates 7 by various techniques.
10. Nanos kovinskih elektrod 4 je zlahka prilagojen proizvodnji večjega obsega (vključno s sitotiskom paste, brizgalnim tiskanjem, izparevanjem, pršenjem in elektro-kemičnim nanašanjem).10. The application of metal electrodes 4 is easily adapted to large-scale production (including screen printing, paste printing, inkjet evaporation, spraying and electrochemical application).
PrimerExample
Spodnji primer ponazarja iznajdbo, vendar iznajdba nikakor ni vezana le na ta primer.The example below illustrates the invention, but the invention is by no means related only to this case.
Senzorski sistem prikazan na Sliki 3 je zgrajen iz niza štirih parov geometrično enakih interdigitalnih elektrod 4, nanesenih na oksidiran silicijev substrat 7, z režo 8 med elektrodama 4, ki meri 2 mikrometra. Sliki 2 prikazuje enojni element. Vsak elektrodni par 4 je narejen iz drugačne kovine, s pršenjem nanesen na substrat Si/Si oksid (7) in oblikovan z uporabo litografije z elektronskim žarkom.The sensor system shown in Figure 3 is constructed from a series of four pairs of geometrically identical interdigital electrodes 4 applied to the oxidized silicon substrate 7, with a gap 8 between electrodes 4 measuring 2 micrometers. Figure 2 shows a single element. Each electrode pair 4 is made of a different metal, sprayed onto a Si / Si oxide substrate (7) and molded using electron beam lithography.
Svežnji nanožic 6 (Mo6S3l6) z različnimi premeri so naneseni čez vsak elektrodni par 4 z dielektroforezo na tak način, da ustvarijo kontakte z obema elektrodama 4, kot prikazuje Sliki 3. Senzorski niz je nameščen v primerno mikro celico, v katero so analiti 1 vnešeni z nosilnim plinom, dušikom. Sprememba upora, ki nastane zaradi prisotnosti analita 1, se meri s standardnim multimetrom z visoko impedanco. Sprememba upora je različna pri različnih analitih 1, kot je prikazano v primeru elektrode Au nanešene na kovino Ti, in sledi krivulji značilne občutljivosti, kot so jo predpostavili M. Devetak et al., (Chem. Mater. vol. 20, str. 1773-177 (2008)). Ta krivulja prikazuje odzivnost senzorja kot funkcijo koncentracije v ppm za primere različnih enalitov. Izpostavljenost senzorja štirih elementov narejenih iz Ni 9, Pd 10, Pt 11 in Ti 12 hlapom vode, metanola, 2-butanola in acetona pokaže povečan upor,Bundles of nanowires 6 (Mo 6 S3l6) of different diameters are applied across each electrode pair 4 by dielectrophoresis in such a way as to create contacts with both electrodes 4, as shown in Figure 3. The sensor array is housed in a suitable micro cell into which the analytes are housed. 1 introduced with carrier gas, nitrogen. The resistance change due to the presence of analyte 1 is measured by a standard high impedance multimeter. The change in resistance is different for different analytes 1, as shown in the case of an Au electrode deposited on a Ti metal, and follows a characteristic sensitivity curve, as assumed by M. Devetak et al., (Chem. Mater. Vol. 20, p. 1773 -177 (2008). This curve shows the response of the sensor as a function of concentration in ppm for cases of different enalites. The exposure of the four element sensor made of Ni 9, Pd 10, Pt 11 and Ti 12 to the vapor of water, methanol, 2-butanol and acetone shows increased resistance,
-9ki je odvisen od koncentracije hlapov analita 1 in ki je različen za vsako kombinacijo kovine analita in elektrode, kot to prikazuje Sliki 5. Končni odziv večelementnega senzorja analiziramo z uporabo primernih algoritmov, na primer PCA, ali z nevronskimi mrežnimi programi.-9ki depends on the vapor concentration of analyte 1 and is different for each combination of analyte metal and electrode, as shown in Figure 5. The final response of a multi-element sensor is analyzed using suitable algorithms, such as PCA, or neural network programs.
V primeru opisanega izuma je niz senzorjev vonjav osnovan na meritvah upora stičišč nanožic 6 in različnih kovin in je sestavljen iz več elementov, od katerih vsak zaznava prisotnost analita ali analitov 1 v območju kapilarne kondenzacije 5 med nanožico ali nanožicami 6 in prevodnima elektrodama 4 in kjer je vsak element narejen iz drugačnega materiala. Senzorjeva občutljivost na različne analite 1 je odvisna od izbire materiala za prevodno elektrodo, na primer Ti, Ni, Zn, Au, itd., prevodnega materiala, na primer InSnO, prevodnega polimera ali kontaktne paste 3, po možnosti ogljikove kontaktne paste. Senzorske lastnosti nastanejo zaradi spremembe impedance električnega kontakta med nanožico 6 in elektrodama 4, ki se pojavi zaradi prisotnosti molekul analita 1 v območju kapilarne kondenzacije 5 med elektrodama 4 in nanožico 6 nameščeno nad elektrodi 4.In the present invention, the set of odor sensors is based on measurements of the resistance of the junctions of nanowires 6 and various metals and consists of several elements, each of which detects the presence of analyte or analytes 1 in the area of capillary condensation 5 between the nanowire or nanowires 6 and the conducting electrodes 4 and each element is made of a different material. Sensor sensitivity to different analytes 1 depends on the choice of conductive electrode material, for example Ti, Ni, Zn, Au, etc., a conductive material, such as InSnO, a conductive polymer, or contact paste 3, preferably a carbon contact paste. Sensory properties are due to the change in impedance of electrical contact between nanowire 6 and electrode 4, which occurs due to the presence of analyte 1 molecules in the region of capillary condensation 5 between electrodes 4 and nanowire 6 positioned above electrodes 4.
Večelementni senzorski sistem je sestavljen iz omenjenih senzorjev, čigar elektrode 4 so izdelane iz različnih prevodnih materialov 9-12.The multi-element sensor system consists of said sensors, whose electrodes 4 are made of various conductive materials 9-12.
Elektrode 4 so narejene s tehnologijami sitotiska, brizgalnega tiskanja, pršenja, litografije ali nanosa plasti atomov (ALD) ter z drugimi načini. Elektrodi 4 sta povezani z nanožico 6, z nanocevko ter s kakšnim drugim predmetom ali kompozitom, ki ima tesen kontakt z materialom elektrod 4 in hkrati v PKK 5 pušča dovolj prostora za molekule analitov 1. Elektrode 4 ali nanožice 6 so lahko prekrite z molekulami površinsko aktivne snovi, z nanosom plasti atomov ali čim drugim, da na ta način spremenimo lastnosti v PKK 5.Electrodes 4 are made using screen printing, inkjet, spray, lithography, or atom deposition (ALD) technologies and other means. The electrodes 4 are bonded to the nanowire 6, the nanotube, and any other object or composite that has close contact with the electrode material 4, while leaving enough space in PKK 5 for analyte molecules 1. The electrodes 4 or nanowires 6 can be covered with surface molecules of the active substance, by applying a layer of atoms or otherwise, in order to change the properties in PKK 5.
Značilnost večelementnega senzorskega sistema je torej v tem, da se vsak njegov senzor drugače odziva na analit 1.The feature of a multi-element sensor system is therefore that each of its sensors responds differently to analyte 1.
Senzorski sistem prepoznava vonjave zato, ker se vsak element v nizu različno odziva na določen analit 1, s čimer se ustvari odtis vsakega analita 1; senzor lahko zaznava prisotnost določenega analita 1 v množici istočasno prisotnih analitov 1.The sensing system recognizes odors because each element in the array responds differently to a particular analyte 1, thereby creating a footprint for each analyte 1; the sensor can detect the presence of a particular analyte 1 in a plurality of analytes 1 present simultaneously.
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