Wearable Temperature Sensor Using Carbon Black Film

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Solution Overview

Problem

Existing body temperature measurement devices are either too bulky or expensive for continuous monitoring, and they often cannot easily measure temperature from exhaled breath due to size constraints.

Innovation Solution

A low-cost, scalable wearable sensor using a polyimide substrate with silver nano-particle interdigital electrodes and a carbon black sensing film, encapsulated with polydimethylsiloxane, which changes electrical resistance in response to temperature variations, allowing for real-time temperature and respiration rate monitoring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional body temperature measurement devices are used, then measurement accuracy is achieved, but device size becomes bulky and cost increases

Engineering Contradiction:

Improvetemperature measurement accuracyVSAvoiddevice size

Core Design Contradiction:

Measurement precisionVSVolume of moving object

Solution Approach 1:

The patent uses a thin flexible substrate as the base for the temperature sensor, allowing it to be conformable and wearable while maintaining measurement functionality. This resolves the contradiction by enabling accurate temperature measurement in a thin, flexible form factor rather than a bulky rigid structure

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent employs materials whose electrical resistance changes with temperature (thermistor materials), converting temperature measurement into an electrical signal measurement. This allows for compact sensor design while maintaining measurement accuracy through material property utilization

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If traditional body temperature measurement devices are used, then measurement capability is achieved, but manufacturing cost increases

Engineering Contradiction:

Improvetemperature measurement capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent employs inexpensive materials such as carbon-based thermistor materials and flexible polymer substrates that can be manufactured at low cost. The sensor is designed to be disposable or easily replaceable, resolving the contradiction by achieving measurement capability through low-cost material selection and simplified manufacturing

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent replaces complex mechanical temperature measurement mechanisms with simple electrical resistance-based sensing. This substitution dramatically reduces manufacturing complexity and cost while maintaining measurement capability through electrical rather than mechanical means

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If sensor components are exposed to environment, then manufacturing simplicity is maintained, but reliability decreases due to humidity and oxidation

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidprotection from environmental factors

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent uses a flexible encapsulation layer deposited over the sensor components to provide environmental protection. This thin film barrier prevents humidity and oxidation while maintaining the flexibility and simplicity of the overall device structure, resolving the contradiction between manufacturing ease and environmental reliability

Inventive Principle:

Principle #30Flexible shells and thin films

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 wearable sensor provides accurate and continuous temperature measurements within a range of 28° C to 50° C, is waterproof, and can be easily integrated into clothing or worn on the skin, enabling effective health monitoring without the limitations of existing devices.

Implementation Method 1

A resistance between the first electrode and the second electrode changes in response to a change in temperature surrounding the sensing film

Methodology Applied

Scientific EffectThermal resistance change: Thermo-resistive Effect

Data Source

PatentUS20230190112A1Low-cost and scalable screen printed wearable human body temperature sensor

Publication Date: 2023.06.22 HAMAD BIN KHALIFA UNIVERSITY

AI summary

A wearable sensor for real-time human body temperature measurement is provided. The wearable sensor includes a substrate, a first electrode on the substrate, a second electrode on the substrate, the second electrode being spaced apart from the first electrode, and a sensing film on the substrate. The sensing film is electrically and/or spatially disposed between the first electrode and the second electrode. A resistance between the first electrode and the second electrode changes in response to a change in temperature surrounding the sensing film.