Strain Sensing Pressure Sensor for Compact Microphone Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Capacitive microphones face sensitivity deterioration when downsized due to reduced electrode areas, and conventional strain sensing devices experience sensitivity loss when scaled down, making it difficult to maintain effective pressure detection in compact designs.
Innovation Solution
A pressure sensor design incorporating a flexible transducer thin film with strategically placed strain sensing devices, including magnetic layers and intermediate layers, which utilize the inverse magnetostrictive effect to maintain sensitivity, allowing for downsizing while preserving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the microphone is downsized to reduce device size, then the overall device dimensions are reduced, but the sensitivity deteriorates due to reduced electrode areas
Solution Approach 1:
The patent replaces the conventional capacitive sensing mechanism with a strain sensing device that detects mechanical deformation directly. The strain sensing device includes a flexible substrate with piezoelectric or piezoresistive elements that convert mechanical strain from sound wave pressure into electrical signals, eliminating the need for large electrode areas while maintaining sensitivity
Solution Approach 2:
The patent changes the sensing mechanism from capacitive coupling (which depends on electrode area) to strain-based detection (which depends on material properties and deformation). By using piezoelectric or piezoresistive materials with high gauge factors, the system achieves high sensitivity in a compact form factor where the sensing element responds to dimensional changes rather than area changes
2Volume of moving object
If conventional strain sensing devices are scaled down to reduce size, then the device dimensions are reduced, but sensitivity is lost
Solution Approach 1:
The patent employs composite structures combining flexible substrates with piezoelectric or piezoresistive material layers. This composite approach allows the sensing element to maintain high sensitivity through material properties (piezoelectric coefficients or piezoresistive gauge factors) rather than dimensional scaling, enabling compact design without sensitivity loss
Solution Approach 2:
The strain sensing device concentrates the sensing function in a localized region with optimized material properties. The flexible substrate with embedded piezoelectric/piezoresistive elements creates a localized high-sensitivity zone that does not require overall device scaling, maintaining detection capability in a compact footprint
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 enables highly sensitive pressure detection across a wide frequency band, improving measurement accuracy and maintaining sensitivity even when the device is scaled down, unlike conventional capacitive and resistive pressure sensors.
Implementation Method 1
strategically placed strain sensing devices, including magnetic layers and intermediate layers, which utilize the inverse magnetostrictive effect to maintain sensitivity
Data Source
AI summary
According to one embodiment, a pressure sensor includes a base, and a first sensor unit. The first sensor unit includes a first transducer thin film, a first strain sensing device and a second strain sensing device. The first strain sensing device includes a first magnetic layer, a second magnetic layer, and a first intermediate layer provided between the first and the second magnetic layers. The second strain sensing device is provided apart from the first strain sensing device on the first membrane surface and provided at a location different from a location of the barycenter, the second strain sensing device including a third magnetic layer, a fourth magnetic layer, and a second intermediate layer provided between the third and the fourth magnetic layers, the first and the second intermediate layers being nonmagnetic. The first and the second strain sensing devices, and the barycenter are in a straight line.