Fiber Optic MEMS Microphone With Laser-Powered Active Membrane
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Solution Overview
Problem
Conventional MEMS microphones are limited by sensitivity and accuracy in harsh environments due to electrical noise and require additional components like high impedance preamplifiers, which restrict their application and performance, especially in confined spaces.
Innovation Solution
A laser-powered active MEMS fiber-optic acoustic sensor microphone with an electrically deflectable membrane and a photodiode chip that converts laser light into electrical power, eliminating impractical electrical conduction and allowing for adjustable sensitivity and resonance frequency, enabling operation over a wide frequency range with improved immunity to environmental effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electrical measurements (current/voltage or capacitive) are used in MEMS microphones, then the microphone can detect audible frequency range, but the measurements are vulnerable to electrical noise and require additional high impedance preamplifiers that reduce performance and are restricted in confined spaces
Solution Approach 1:
The patent replaces electrical measurement systems with optical measurement systems. Instead of using electrical current/voltage or capacitive measurements that are vulnerable to electrical noise, the invention uses optical interferometry to detect membrane displacement. The optical system measures the position of the membrane by detecting phase or intensity changes of light, completely eliminating susceptibility to electrical noise while maintaining high measurement precision for audible frequency detection
Solution Approach 2:
The patent introduces optical interferometry as an intermediary measurement mechanism. The optical system acts as a mediator between the mechanical membrane vibration and the detection system, converting mechanical displacement into optical signal changes that can be measured without electrical contact, thus avoiding electrical noise while preserving measurement accuracy
2Ease of operation
If conventional MEMS microphones use electrical components, then they can operate with standard electronics, but they suffer from electromagnetic interference and require additional high impedance preamplifiers that increase device complexity
Solution Approach 1:
The patent replaces the electrical operation system with an optical operation system. The microphone membrane is still mechanically actuated by sound waves, but the detection and signal generation are performed optically using interferometry. This eliminates the need for high impedance preamplifiers and other electrical components, reducing device complexity while maintaining ease of operation through optical signal processing
Solution Approach 2:
The patent extracts and removes the vulnerable electrical components (high impedance preamplifiers, electrical connections) from the microphone system. By using optical interferometry for detection, the invention eliminates the need for these additional components, simplifying the overall device structure while maintaining full operational capability through non-electrical means
3Device complexity
If passive MEMS devices are used in fiber optic microphones, then the design is simpler, but the sensitivity is limited and constant in operation
Solution Approach 1:
The patent transforms the static, passive MEMS device into a dynamic, active system. By integrating a piezoelectric actuator with the membrane, the system can dynamically adjust the membrane tension and resonance frequency in real-time. This dynamic control enables variable sensitivity settings, allowing the microphone to adapt to different operating conditions and achieve optimal sensitivity across a wide frequency range, while maintaining the fundamental simplicity of the MEMS structure
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 high sensitivity and dynamic response, with a fundamental resonance frequency above the audible range, allowing for accurate sound wave detection and reduced electromagnetic interference, enhancing the microphone's performance and flexibility in various applications.
Implementation Method 1
A laser-powered active MEMS fiber-optic acoustic sensor microphone with an electrically deflectable membrane and a photodiode chip that converts laser light into electrical power
Implementation Method 2
The MEMS device which is capable of reflecting part of the incident laser light from the membrane back to the optical fiber
Implementation Method 3
A laser-powered active MEMS fiber-optic acoustic sensor microphone with an electrically deflectable membrane
Data Source
AI summary
A fiber optic MEMS microphone featuring an electrically deflectable MEMS membrane via a conversion of an optical energy propagating in an optical fiber cable to an electrical energy with a photodiode chip. The fiber optic MEMS microphone includes a MEMS device, the photodiode chip, a voltage, a power adjustable laser beam and a light.