Flexible Temperature Sensor with Steinhart-Hart Calibration
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Solution Overview
Problem
Current deep tissue temperature measurement devices are either invasive, costly, or lack accuracy due to batch-to-batch manufacturing variances in thermistor resistance, which complicates reliable non-invasive, zero-heat-flux deep tissue temperature estimation.
Innovation Solution
A disposable, zero-heat-flux deep tissue temperature measurement device featuring a flexible substrate with an electrical circuit including thermal sensors and a heater, where thermistors are calibrated using the Steinhart-Hart equation to minimize resistance variance, and a layout that maintains thermal sensors in a thermally isolated zone to enhance measurement accuracy and reduce thermal interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermistors are used for temperature measurement, then temperature sensing capability is provided, but batch-to-batch manufacturing variances in resistance cause measurement inaccuracy
Solution Approach 1:
The patent applies parameter changes by using the Steinhart-Hart equation to calibrate thermistor resistance values. Instead of relying on fixed nominal resistance values that vary between batches, the system measures actual resistance and converts it to temperature using calibrated parameters (A, B, C coefficients), thereby compensating for manufacturing variances and improving measurement accuracy.
Solution Approach 2:
The patent implements feedback through the calibration process where actual thermistor resistance measurements are fed back into the Steinhart-Hart equation with adjusted parameters. The system continuously refines temperature calculations based on measured resistance values, creating a closed-loop correction mechanism that accounts for manufacturing tolerances.
2Volume of moving object
If thermal sensors are placed close together for compact design, then device profile is reduced, but thermal interference between sensors increases
Solution Approach 1:
The patent introduces thermal insulation material as an intermediary between the deep tissue temperature sensor and skin temperature sensor. This insulating layer acts as a thermal barrier that prevents heat from the skin sensor from interfering with the deep tissue sensor measurements, allowing the sensors to be placed in close proximity while maintaining measurement accuracy.
Solution Approach 2:
The patent applies local quality by providing thermal insulation specifically in the region between the two sensors, rather than insulating the entire device. The insulation is localized to where thermal interference occurs, maintaining compact overall dimensions while protecting the sensitive measurement zone from thermal cross-contamination.
3Ease of manufacture
If disposable device construction is used, then manufacturing cost is reduced and ease of manufacture is improved, but device complexity increases due to assembly requirements
Solution Approach 1:
The patent merges multiple components into a single integrated disposable unit. The flexible substrate integrates the heater circuit, thermistor sensors, thermal insulation, and adhesive layers into one cohesive structure that can be manufactured as a single piece or pre-assembled module, eliminating the need for complex assembly procedures while maintaining disposability.
Solution Approach 2:
The patent uses a flexible substrate as the base structure that integrates multiple functions. This thin film approach allows the device to be manufactured using flexible printing and lamination techniques, simplifying production while maintaining a compact, disposable form factor that requires minimal assembly steps.
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 device provides accurate and reliable non-invasive deep tissue temperature measurement with reduced manufacturing costs and improved stability, addressing the limitations of existing technologies by ensuring precise temperature estimation while maintaining a low profile and lightweight design.
Implementation Method 1
at least three thermal sensors including at least one skin thermal sensor
Implementation Method 2
The substrate supports at least the thermal sensors, the separating thermal insulator, and a heater
Implementation Method 3
separated by one or more flexible layers of thermally insulating material
Data Source
AI summary
Aspects of the present disclosure relate to a temperature device having a flexible substrate; and an electrical circuit on a surface of the flexible substrate. The electrical circuit includes at least three thermal sensors including at least one skin thermal sensor, a plurality of electrical pads, a plurality of conductive traces connecting the at least three thermal sensors with the plurality of electrical pads.