An improved chemiresistor sensor

Patent metadata

Field	Value
Publication number	US-2016282302-A1
Application number	US-201414778305-A
Country	US
Kind code	A1
Filing date	Mar 19, 2014
Priority date	Mar 21, 2013
Publication date	Sep 29, 2016
Grant date	—

Abstract

A sensor is provided for measuring the presence or amount of an ionic analyte in an electrolyte solution. The sensor comprises (i) two electrically conducting electrodes on an electrically insulating substrate, and separated by a distance L, where L is between 10 nm and 100 μm; (ii) a chemiresistor film, wherein the impedance of the chemiresistor film changes in the presence of an ionic analyte; and wherein the chemiresistor film is in contact with the electrodes; (iii) a gate electrode formed from an electrically conductive material; (iv) a potential generator means configured to apply an electrical potential difference between the gate electrode and the chemiresistor film; (v) a controller to selectively control the potential generator means to apply either a positive electric potential or a negative electric potential to the gate electrode relative to the potential of the chemiresistor film; and (vi) a voltage means adapted to apply a voltage signal between said pair of electrically conducting electrodes to enable measurement of the resistance of the chemiresistor film.

First claim

1 . A sensor for measuring the presence or amount of an ionic analyte in an electrolyte solution, said sensor comprising:
(i) two electrically conducting electrodes on an electrically insulating substrate, and separated by a distance L, where L is between 10 nm and 100 μm; (ii) a chemiresistor film, wherein the impedance of the chemiresistor film changes in the presence of an ionic analyte; and wherein the chemiresistor film is in contact with the electrodes; (iii) a gate electrode formed from an electrically conductive material; (iv) a potential generator means configured to apply an electrical potential difference between the gate electrode and the chemiresistor film; (v) a controller to selectively control the potential generator means to apply either a positive electric potential or a negative electric potential to the gate electrode relative to the potential of the chemiresistor film; and (vi) a voltage means adapted to apply a voltage signal between said pair of electrically conducting electrodes to enable measurement of the resistance of the chemiresistor film.

2 . A sensor according to claim 1 , wherein the gate electrode is one of a gold electrode, a platinum electrode, a palladium electrode, a silver electrode, a carbon electrode, an Ag/AgCl gate electrode, and an Ag/AgCl gate electrode where the silver has been chlorided.

3 . A sensor according to claim 1 , wherein the gate electrode comprises a counter electrode and a reference electrode.

4 . A sensor according to claim 3 , wherein the counter electrode is formed from one of gold, platinum, palladium, silver and a conductive carbon material.

5 . A sensor according to claim 3 , wherein the reference electrode is selected from one of a Ag/AgCl electrode, a non-aqueous Ag/Ag+ electrode, a mercury/mercurous sulphate electrode and a saturated calomel electrode.

6 . A sensor according to claim 1 , where the two electrically conducting electrodes are each formed from either an inert material selected from gold, palladium, platinum, silver, copper and nickel or a conductive material based on conductive carbon selected from carbon black, graphene and carbon nanotubes.

7 . A sensor according to claim 1 , wherein the two electrically conducting electrodes are respectively coated with a thin layer of an inert material, the inert material characterised by:
(a) having a dielectric constant that is less than that of water; (b) being at least partially impermeable towards ions; and (c) having a thickness less than 2 nanometres.

8 . A sensor according to claim 7 wherein each of the two electrically conducting electrodes are formed from either gold, silver, palladium or a platinum electrode material, and the thin layer of the inert material is a self-assembled monolayer formed onto the surface of the each of the electrodes.

9 . A sensor according to claim 1 , wherein the voltage means is configured to provide a low frequency f<f 0 =100 Hz signal or DC across said electrodes; and wherein the amplitude of the applied voltage is between 10 mV and 500 mV.

10 . A sensor according to claim 1 , wherein said chemiresistor film comprises a conductive particulate material with junctions therebetween comprising of a non-conductive material.

11 . A sensor according to claim 10 , wherein the conductive particulate material comprises one of a metallic conductor, an inorganic conductor, an organic conductor, or an organic conducting polymer or mixtures thereof.

12 . A sensor according to claim 10 , wherein said conductive particulate material comprises nanoparticles coated with a non-conductive organic material that is an organic ligand or a mixture of ligands.

13 . A sensor according to claim 12 , wherein said nanoparticles have diameters less than 100 nm and greater than 2 nm, and more preferably less than 50 nm and greater than 2 nm.

14 . A sensor according to claim 12 , wherein said conductive nanoparticles are made from gold, silver, platinum or palladium.

15 . A sensor according to claim 1 , wherein said chemiresistor film is an organic conductor with an insulating organic molecule or a polymer or an organic conductive polymer.

16 . A method for measuring the presence or amount of an ionic analyte in an electrolyte solution using a sensor according to claim 1 , the method comprising:
(i) contacting the chemiresistive material with an electrolyte solution; (ii) applying an electric potential difference between the gate electrode and the chemiresistive material; and (iii) measuring the change in the resistance of the chemiresistive material.

17 . A method according to claim 16 , further comprising the step of comparing the value of the measurement in step (iii) with measurement(s) of the change in the resistance of the chemiresistive material in the presence of said ionic analyte at one or more known concentrations to thereby determine the amount of ionic analyte in said electrolyte solution.

18 . A method for modulating the electrical resistance of a chemiresistive material using a sensor according to claim 1 , the method comprising:
(i) contacting the chemiresistive material and the gate electrode with an electrolyte solution; (ii) applying an electric potential difference between the gate electrode and the chemiresistive material; (iii) selectively charging the gate electrode with a net positive charge or a net negative charge; and (iv) measuring the change in the resistance of the chemiresistive material.

19 . A method according to claim 18 , wherein the charged analyte molecule comprises one or more positive charges (P) or one or more negative charges (N), such that overall the charged analyte molecule has either a net positive charge in the case of (P) or net negative charge in the case of (N), and an interaction group (F) of the following structure: P---F or N---F respectively.

20 . A method according to claim 19 , wherein the interaction group (F) is (i) an organic functional group which comprises one or more chemical moieties capable of physically or chemically binding to the chemiresistive material; or (ii) contains as part of its structure, a hydrophobic group such as a hydrocarbon-containing moiety; or (iii) contains as part of its structure groups capable of forming hydrogen bonds.

Assignees

• Commw Scient Ind Res Org

Inventors

• Raguse Burkhard
• Chow Edith

Classifications

• G01N27/04

  by investigating resistance · CPC title

• G01N27/127

  comprising nanoparticles · CPC title

• G01N27/128

  Microapparatus · CPC title

• G01N33/54393

  Improving reaction conditions or stability, e.g. by coating or irradiation of surface, by reduction of non-specific binding, by promotion of specific binding · CPC title

• G01N33/5438

  Electrodes · CPC title