MEMS Optical Microphone Tunable Diaphragm-Reflector Distance
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Solution Overview
Problem
MEMS optical microphones face challenges in achieving high signal-to-noise ratio (SNR) and efficient sound detection due to limitations in design and interference pattern resolution, particularly in maintaining an optimal distance between the diaphragm and reflector to minimize noise penalties like the squeeze film effect.
Innovation Solution
A MEMS optical microphone design featuring a single plate with a compliant membrane and a grating, where the light emitter and detector are positioned to detect interference patterns indicative of acoustic vibrations, and circuitry is used to tune the distance between the diaphragm and reflector for improved resonance and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the distance between the diaphragm and reflector is reduced to minimize the squeeze film effect, then noise penalties are reduced, but the interference pattern resolution deteriorates
Solution Approach 1:
The patent implements a tunable distance mechanism between the diaphragm and reflector, allowing the system to dynamically adjust the spacing based on operating conditions. This enables optimization of both noise reduction and interference pattern resolution by selecting appropriate distance settings for different应用场景
Solution Approach 2:
The system changes the physical parameter of distance between diaphragm and reflector to resolve the contradiction. By making this parameter adjustable rather than fixed, the system can optimize performance for different operating conditions, achieving both low noise and high resolution when needed
2Device complexity
If a single plate design is used to simplify the structure, then device complexity is reduced, but control over diaphragm-reflector distance becomes more difficult
Solution Approach 1:
The single plate structure serves multiple functions: it acts as both the diaphragm and incorporates the reflector functionality within the same component. This multi-functionality reduces the number of separate parts while maintaining the necessary tuning capability through integrated design features
Solution Approach 2:
The reflector structure is nested within or integrated into the single plate diaphragm structure. This nesting approach allows the system to maintain complex functionality (distance tuning) within a simplified single-plate form factor, reducing overall device complexity while preserving operational capability
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 achieves a high signal-to-noise ratio and reduces noise penalties by allowing for precise tuning of the distance between the diaphragm and reflector, enhancing the resolution of interference patterns and improving sound detection efficiency.
Implementation Method 1
The emitter is configured to transmit a laser light toward the grating and the reflector. A light detector is positioned along the same side of the compliant membrane as the light emitter, the light detector configured to detect an interference pattern of the laser light, which is indicative of an acoustic vibration of the compliant membrane.
Implementation Method 2
The light beam is diffracted by the grating and then reflected off of the reflective portion of the diaphragm back to the light detector.
Implementation Method 3
The light beam is diffracted by the grating and then reflected off of the reflective portion of the diaphragm back to the light detector.
Data Source
AI summary
A micro-electro-mechanical system (MEMS) optical sensor including an enclosure having a top wall, a bottom wall and a sidewall connecting the top wall and the bottom wall. The sensor further including a compliant membrane positioned within the enclosure, which is configured to vibrate in response to an acoustic wave and having a grating formed therein. A reflector is formed directly on an inner surface of one of the bottom wall or the top wall of the enclosure. A light emitter is positioned within the enclosure along a side of the compliant membrane opposite the reflector, the light emitter is configured to transmit a laser light toward the grating and the reflector. A light detector is positioned along the side of the compliant membrane opposite the reflector, the light detector configured to detect an interference pattern of the laser light, which is indicative of an acoustic vibration of the compliant membrane.