Thin-Film Piezoresistive Pressure Sensor for Compact High-Sensitivity Design
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Solution Overview
Problem
Existing pressure sensing devices require a large space and offer low sensitivity.
Innovation Solution
A pressure sensing device featuring a thin-film piezoresistive sensor with signal wires attached to a substrate, where the sensor's resistivity changes with substrate deformation, allowing for pressure detection through voltage drop between differential wires, and a method involving equivalent circuits to process the signal for precise pressure measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a strain gauge pressure sensor is used, then the device can sense pressure signals, but the device requires a relatively large space and provides low sensitivity
Solution Approach 1:
The patent changes the material parameter from conventional strain gauge material to thin-film piezoresistive material, which has higher piezoresistive coefficients. This parameter change enables the sensor to achieve higher sensitivity while maintaining a compact form factor, directly resolving the contradiction between measurement precision and device area
Solution Approach 2:
The patent replaces the conventional mechanical strain gauge system with an electrical thin-film piezoresistive system. By substituting the mechanical measurement approach with an electrical field-based approach using thin-film deposition techniques, the device achieves both compact size and high sensitivity, resolving the space-sensitivity contradiction
2Measurement precision
If a thin-film piezoresistive sensor is used, then the sensitivity is high and area is small, but temperature drift and interference need to be compensated
Solution Approach 1:
The patent implements a full-bridge circuit configuration where temperature-induced resistance changes in all four arms of the bridge produce equal voltage changes that cancel each other out. This feedback mechanism through the bridge circuit automatically compensates for temperature drift, allowing the sensor to maintain high sensitivity while rejecting temperature interference
Solution Approach 2:
The patent uses composite material structures combining thin-film piezoresistive layers with appropriate substrate materials and protective coatings. This composite approach not only achieves high sensitivity through the piezoresistive effect but also provides temperature compensation and interference rejection through the combined properties of different materials
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 solution provides a compact pressure sensing device with high sensitivity, small temperature drift, strong anti-interference ability, and stable reliability, enabling precise pressure detection and touch functionality.
Implementation Method 1
resistivity distribution of the thin-film piezoresistive sensor changes with deformation of the substrate when the substrate deforms
Data Source
AI summary
The pressure sensing device includes a substrate and a pressure sensor. The pressure sensor used is a thin-film piezoresistive sensor with a certain area, and a power wire, a ground wire, and two differential wires are led out from ends of the pressure sensor respectively, and the pressure sensor is arranged on the substrate. The substrate is simply attached to the object being tested that is to be subjected to pressure, the pressure sensor is connected to a pressure sensing detection circuit, the object being tested deforms under pressure, and the thin-film piezoresistive sensor deforms as the substrate deforms. The deformation of the substrate is detected through detecting the voltage drop between the two differential wires, which is converted to obtain the pressure on the object being tested, thereby realizing a pressure-sensitive touch function. A pressure sensing method and an electronic terminal with the pressure sensing device are also provided.