Bioacoustic Sensor Diaphragm Gap Design for Vibration Sensitivity

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Solution Overview

Problem

Bioacoustic sensors with piezoelectric plates attached entirely to a housing have limited deformation, resulting in low vibration detection sensitivity when in contact with a living body.

Innovation Solution

A bioacoustic sensor design featuring a diaphragm with a contact surface and a back surface, where the diaphragm is displaceable in the thickness direction, and a piezoelectric plate with a gap between its surfaces, allowing the diaphragm to contact either the center or outer side of the piezoelectric plate, and the housing supports the opposite side, enhancing vibration detection sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the piezoelectric plate is attached entirely to the housing, then the structural stability is improved, but the vibration detection sensitivity deteriorates

Engineering Contradiction:

Improvestructural stabilityVSAvoidvibration detection sensitivity

Core Design Contradiction:

Stability of the object's compositionVSMeasurement precision

Solution Approach 1:

The patent divides the attachment area of the piezoelectric plate into two segments: a first attachment area on the housing and a second attachment area on the diaphragm. This segmentation allows the plate to be supported at both ends while maintaining contact with the living body through the diaphragm, thereby improving vibration detection sensitivity without compromising structural stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The diaphragm serves as an intermediary element between the piezoelectric plate and the living body. The piezoelectric plate contacts the diaphragm at the second attachment area, allowing vibration transmission from the living body through the diaphragm to the plate, while the housing provides structural support. This intermediary arrangement resolves the contradiction between stability and sensitivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If the piezoelectric plate is attached entirely to the housing, then the manufacturing simplicity is improved, but the vibration detection sensitivity deteriorates

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidvibration detection sensitivity

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The attachment structure is segmented into a first attachment area on the housing and a second attachment area on the diaphragm. This segmentation enables the piezoelectric plate to function effectively as a vibration sensor while maintaining relatively simple manufacturing processes, thus resolving the contradiction between manufacturing simplicity and vibration detection sensitivity.

Inventive Principle:

Principle #1Segmentation

3Strength

If the piezoelectric plate is attached entirely to the housing, then the structural rigidity is improved, but the deformation capability deteriorates

Engineering Contradiction:

Improvestructural rigidityVSAvoiddeformation capability

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The attachment structure is divided into a first attachment area on the housing and a second attachment area on the diaphragm. This segmentation allows the piezoelectric plate to maintain structural rigidity through housing support while enabling necessary deformation through diaphragm contact, thereby resolving the contradiction between structural rigidity and deformation capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different areas of the piezoelectric plate have different attachment characteristics: the first attachment area contacts the housing for structural support and rigidity, while the second attachment area contacts the diaphragm for vibration transmission and deformation. This local differentiation of attachment quality resolves the contradiction between overall structural rigidity and local deformation capability.

Inventive Principle:

Principle #3Local quality

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 design increases vibration detection sensitivity by allowing greater flexibility and reducing the risk of excessive flexural deformation of the piezoelectric plate, thereby improving the sensor's ability to detect vibrations, especially those with small amplitudes or high frequencies.

Implementation Method 1

a piezoelectric plate including a first surface facing the back surface of the diaphragm with a gap between the first surface and the back surface and a second surface on an opposite side to the first surface to convert vibration of the diaphragm into an electric signal

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS20240397259A1Bioacoustic sensor and stethoscope including the same

Publication Date: 2024.11.28 MURATA MFG CO LTD

AI summary

A bioacoustic sensor includes a diaphragm including a contact surface contactable with a living body and a back surface, and being displaceable in a thickness direction, and a piezoelectric plate including a first surface facing the back surface of the diaphragm with a gap therebetween and a second surface on a side opposite to the first surface to convert the vibration of the diaphragm into an electric signal. The diaphragm is in contact with a center side portion of the first surface of the piezoelectric plate when viewed in the thickness direction, and a housing supports an outer side portion of the second surface of the piezoelectric plate when viewed in the thickness direction.