Vapor Sensor Matrix with Opposing Temperature Coefficients

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conductometric sensor films face challenges in maintaining sensitivity to chemical analytes while minimizing sensitivity to temperature fluctuations, leading to instability and reduced accuracy in detecting target analytes.

Innovation Solution

A sensor matrix is created using a combination of a polymer resin and conductive particles with opposing temperature coefficients of resistance, where the first species has a positive temperature coefficient and the second species has a negative temperature coefficient, minimizing resistance changes due to temperature variations and enhancing sensitivity to target analytes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a polymer-absorption chemiresistor sensor is used to detect target analytes through volumetric changes, then sensitivity to chemical analytes is improved, but sensitivity to temperature fluctuations increases causing instability

Engineering Contradiction:

Improvedetection sensitivity to chemical analytesVSAvoidsensor stability against temperature variations

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent uses a composite material system consisting of a polymer matrix combined with conductive particles having specific temperature coefficients of resistance. The polymer matrix provides analyte detection capability while the conductive particles with opposing temperature coefficients (positive and negative) compensate for temperature-induced resistance changes, creating a composite material that simultaneously achieves chemical sensitivity and temperature stability

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the physical-chemical parameters of the sensor material by selecting conductive particles with specific temperature coefficients of resistance. By carefully choosing particles with positive temperature coefficients to counterbalance the negative temperature coefficient of the polymer matrix, the overall temperature sensitivity parameter is adjusted to near-zero while maintaining analyte detection functionality

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If conductive particles are added to enhance sensitivity to resistance changes, then detection capability is improved, but cross-sensitivity to temperature increases

Engineering Contradiction:

Improveresistance change sensitivityVSAvoidtemperature cross-sensitivity

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful temperature sensitivity of conductive particles into a beneficial compensatory mechanism. By selecting conductive particles with positive temperature coefficients of resistance to counterbalance the negative temperature coefficient of the polymer matrix, the temperature cross-sensitivity that would normally be harmful is transformed into a stabilizing effect that improves overall sensor reliability

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The approach results in a sensor with reduced cross-sensitivity to temperature, maintaining stability and accuracy in detecting chemical analytes, thereby improving the robustness and reliability of the sensor film.

Implementation Method 1

At least one of the polymer resin and the first species has one of a positive or a negative first temperature coefficient of resistance associated therewith. The second species has a second temperature coefficient of resistance. The second temperature coefficient of resistance is opposite to that of the first temperature coefficient of resistance.

Methodology Applied

Scientific EffectTemperature coefficient of resistance: Thermistor

Implementation Method 2

The polymer absorbs target analytes and this results in a volumetric change of the film, and hence the change in electrical resistance of the film.

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentUS7708947B2Methods of minimizing temperature cross-sensitivity in vapor sensors and compositions therefor

Publication Date: 2010.05.04 THERM O DISC INC

AI summary

The present invention relates to methods of making compositions for sensor films used for detecting chemical analytes within sensors, such as polymer-absorption chemiresistors (i.e., conductometric sensors). The sensor films have reduced cross-sensitivity to temperature, while maintaining sensitivity to the chemical analytes. The sensor matrix includes components that are associated with a first temperature coefficient of resistance, such as a polymer resin and/or a first conductive particle. The sensor matrix further comprises a second species, preferably a conductive particle, which has a second temperature coefficient of resistance that is opposite to the first temperature coefficient of resistance. The second species has an opposite influence on a resistance response of the sensor from the first species. In this manner, the sensor matrix exhibits a minimized response in resistance to any changes in temperature.