# US 9,518,878 B2 · Apparatus and method for nanocomposite sensors

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- Number: US 9,518,878 B2
- Document ID: US9518878B2
- Status: Granted
- Kind: B2
- Application number: 14/752,102
- Filed: 2015-06-26
- Published: 2015-10-22
- Granted: 2016-12-13
- Earliest claimed: 2009-10-01
- Assignees: Board of Supervisors of Louisiana State University and Agricultural and Mechanical College
- Applicants: Board of Supervisors of Louisiana State University and Agricultural and Mechanical College
- Inventors: Jin-Woo Choi; Chao-Xuan Liu
- Web page: https://patentgrep.com/patent/US9518878B2

## CPC

- G01B 7/18: {using change in resistance}
- B82Y 15/00: Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
- C08K 7/00: Use of ingredients characterised by shape
- G01L 1/20: by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids (of piezo-resistive materials G01L1/18); by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
- G01L 9/0041: {Transmitting or indicating the displacement of flexible diaphragms}
- G01L 9/0042: {Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms (details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively)}
- G01L 9/0051: {using variations in ohmic resistance}
- G01L 9/0054: {integral with a semiconducting diaphragm}
- H01B 1/24: the conductive material comprising carbon-silicon compounds, carbon or silicon
- C08K 2201/00: Specific properties of additives
- C08K 2201/001: Conductive additives
- C08K 2201/011: Nanostructured additives
- Y10T 428/24893: including particulate material
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)
- H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K})
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A sensing material for use in a sensor is disclosed. Such a sensing material includes a polymer base and a piezoresistive nanocomposite embedded into the polymer base in a continuous pattern. The nanocomposite comprises a polymer matrix and a plurality of conductive nanofillers suspended in the matrix. The conductive nanofillers may be one or a combination of nanotubes, nanowires, particles and flakes. The density of the plurality of nanofillers is such that the nanocomposite exhibits conductivity suitable for electronic and sensor applications.

## Claims

### Claim 1

A method for forming a sensing material, comprising:
adding a polymer matrix into a first organic solvent solution and allowing the polymer matrix to dissolve;
dispersing a conductive nanofiller into a second organic solvent solution and stirring;
adding the first organic solvent solution to the second organic solvent solution, forming a mixture, and stirring the mixture;
evaporating the first and second organic solvent solutions from the mixture; and
adding a polymer curing agent to the mixture, forming a conductive nanocomposite, embedding the conductive nanocomposite into a polymer base in a continuous pattern to form the sensing material.

### Claim 2 (depends on 1)

The method of claim 1, wherein the polymer matrix is selected from one of polydimethylsiloxane (PDMS), silicone elastomer, vinyl acetate, ethylene propylene rubber, polyimide, polytetrafluoroethylene (PTFE), poly(p-xylylene) polymer, fluorocarbon-based polymer, and poly(methyl methacrylate) (PMMA).

### Claim 3 (depends on 1)

The method of claim 1, wherein the polymer matrix is added to the first organic solvent solution at a ratio of about 1:4.

### Claim 4 (depends on 1)

The method of claim 1, wherein the nanofiller is added to the second organic solvent solution at a ration of about 1:20.

### Claim 5 (depends on 1)

The method of claim 1, wherein the nanofiller is at least one of a plurality of conductive nanotubes, conductive nanowires, conductive particles and conductive flakes.

### Claim 6 (depends on 1)

The method of claim 1, wherein the first organic solvent solution is selected from one of toluene, chloroform, tetrahydrofuran (THF), dimethylformamide (DMF) and dichloromethane (DCM).

### Claim 7 (depends on 1)

The method of claim 1, wherein the second organic solvent solution is selected from one of toluene, chloroform, tetrahydrofuran (THF), dimethylformamide (DMF) and dichloromethane (DCM).

### Claim 8 (depends on 1)

The method of claim 1, wherein the continuous pattern is one of a line, a curve, or combination thereof.

### Claim 9 (depends on 1)

The method of claim 1, wherein the polymer base is an elastomeric polymer.

### Claim 10 (depends on 1)

The method of claim 1, wherein the polymer matrix is an elastomeric polymer.

### Claim 11 (depends on 1)

The method of claim 1, wherein the polymer base is selected from one of polydimethylsiloxane (PDMS), silicone elastomer, vinyl acetate, ethylene propylene rubber, polyimide, polytetrafluoroethylene (PTFE), poly(p-xylylene) polymer, fluorocarbon-based polymer, and poly(methyl methacrylate) (PMMA).

### Claim 12 (depends on 1)

The method of claim 1, wherein the conductive nanofiller is uniformly distributed in the polymer matrix.

### Claim 13 (depends on 1)

The method of claim 1, wherein the nanocomposite is patterned such that malformation of the polymer base yields a corresponding change to the resistance of the sensing material.