Pickup Sensor with Grounded Electrode Shielding
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Solution Overview
Problem
Throat microphones using piezoelectric elements face challenges in reducing size due to the need for additional sensors and signal processing circuits to prevent unpleasant noise, and electroacoustic converter films are weak to external electromagnetic noise, making it difficult to detect micro vibrations efficiently and accurately.
Innovation Solution
A pickup sensor featuring an electroacoustic converter film with a piezoelectric polymer composite, thin film electrodes, and a protective layer, where one electrode is grounded to act as an electromagnetic shield, allowing for efficient and accurate detection of micro vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a piezoelectric element is used as a vibration detection portion in a throat microphone, then the device can detect throat vibrations, but additional sensors and signal processing circuits are required to prevent unpleasant noise, making it difficult to reduce the device size
Solution Approach 1:
The device is segmented into functional layers: the piezoelectric polymer composite layer for vibration detection, thin film electrodes for electrical signal extraction, and an electromagnetic shield layer for noise protection. This segmentation allows each component to perform its specific function efficiently while maintaining a compact overall structure.
Solution Approach 2:
The electromagnetic shield is nested within the sensor structure, with the piezoelectric polymer composite positioned between the shield and the throat contact surface. This nesting arrangement protects the sensitive piezoelectric element from external electromagnetic noise while maintaining a compact design without requiring separate external shielding components.
2Device complexity
If an electroacoustic converter film is used to reduce device size, then the device becomes small-sized and lightweight, but it is weak to external electromagnetic noise and cannot detect micro vibrations efficiently and accurately
Solution Approach 1:
The electromagnetic shield, which might add weight and complexity, is implemented using a thin film electrode structure that converts the potential harm of electromagnetic noise into a design feature. The shield layer is integrated into the film structure itself, turning a protective measure into part of the lightweight film design rather than an additional component.
Solution Approach 2:
The sensor uses a composite structure combining piezoelectric polymer particles dispersed in a viscoelastic matrix, with thin film electrodes and electromagnetic shield layers. This composite material approach provides both the flexibility and lightness of polymer materials while incorporating the noise-protection properties of conductive shield layers, achieving both miniaturization and noise resistance.
3Measurement precision
If the piezoelectric polymer composite is positioned close to the throat contact surface for direct vibration detection, then micro vibration detection accuracy is improved, but the device becomes more susceptible to electromagnetic noise from external sources
Solution Approach 1:
The electromagnetic shield is positioned between the piezoelectric polymer composite and external electromagnetic noise sources, providing preliminary protection before the noise can reach the sensitive detection elements. This preemptive shielding arrangement prevents noise interference while allowing the piezoelectric composite to maintain its optimal position for direct vibration detection.
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 small-sized, lightweight, and flexible sensors that effectively shield against electromagnetic noise, allowing for stable and accurate detection of micro vibrations, suitable for biological applications such as heart rate monitoring.
Implementation Method 1
a piezoelectric polymer composite in which piezoelectric particles are dispersed in a viscoelastic matrix
Implementation Method 2
the thin film electrode on a surface opposite to the abutting surface is grounded
Data Source
AI summary
Provided are a pickup sensor and a biological sensor that are small-sized and can detect micro vibration efficiently and stably with high accuracy. The pickup sensor includes an electroacoustic converter film including: a piezoelectric polymer composite in which piezoelectric particles are dispersed in a viscoelastic matrix that is formed of a polymer material having viscoelasticity at normal temperature; two thin film electrodes that are laminated on opposite surfaces of the piezoelectric polymer composite, respectively; and a protective layer that is laminated on at least one of the two thin film electrodes, in which at least a part of a surface of the electroacoustic converter film is an abutting surface that abuts against a test object, and the thin film electrode on a surface opposite to the abutting surface is grounded.