Diamond Cantilever Optical Microphone for EMI-Resistant Acoustic Sensing
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Solution Overview
Problem
Traditional electronic microphones face challenges such as insufficient sensitivity, susceptibility to electromagnetic interference, and difficulty adapting to high-temperature, high-humidity, or corrosive environments due to mechanical strength limitations and corrosion issues with metal diaphragms.
Innovation Solution
An optical microphone based on diamond cantilevers, featuring a diamond diaphragm with a U-shaped groove, which is prepared through chemical vapor deposition and dry etching, providing high mechanical sensitivity and resistance to electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If metal material thin films are used as rigid diaphragms with reduced thickness to achieve high sensitivity, then sensitivity is improved, but mechanical strength decreases and residual stresses occur
Solution Approach 1:
The patent changes the material parameter from metal to diamond, fundamentally altering the mechanical properties. Diamond's exceptional strength-to-thickness ratio allows the diaphragm to be made extremely thin (improving sensitivity) while maintaining or even enhancing mechanical strength, thus resolving the contradiction between sensitivity and strength.
Solution Approach 2:
The patent employs a composite structure combining diamond diaphragm with ceramic components and optical fiber elements. This composite approach leverages the superior mechanical properties of diamond while integrating the functional advantages of ceramic and optical materials, achieving both high sensitivity and structural integrity.
2Device complexity
If metal material thin films are used as rigid diaphragms, then compact structure is achieved, but resonance frequency is low restricting bandwidth
Solution Approach 1:
The patent changes the material parameter from metal to diamond, which has fundamentally different elastic and density properties. Diamond's high elastic modulus and low density result in significantly higher resonance frequencies for the same geometric configuration, expanding the usable bandwidth while maintaining compact dimensions.
3Ease of manufacture
If metal materials are used as rigid diaphragms, then ease of manufacture is maintained, but chemical stability is poor increasing susceptibility to corrosion
Solution Approach 1:
The patent changes the material from metal to diamond, which exhibits exceptional chemical inertness. Diamond does not corrode from acidic gases such as HF, SO2, and SF6, completely resolving the chemical stability issue while CVD fabrication methods provide viable manufacturing pathways.
Solution Approach 2:
The patent replaces the traditional metal mechanical diaphragm with a diamond-based optical-mechanical system. This substitution eliminates the corrosion vulnerability of metals while maintaining the mechanical sensing function through diamond's superior properties and optical detection methods.
4Power
If traditional electronic microphones are used, then electromagnetic conversion is achieved, but susceptibility to electromagnetic interference occurs
Solution Approach 1:
The patent replaces the electronic electromagnetic conversion system with an optical-based system. Sound waves cause mechanical vibrations of the diamond diaphragm, which modulate optical properties (such as optical path length or interference patterns), and these optical modulations are then converted to electrical signals. This optical intermediary eliminates direct electromagnetic interference susceptibility while preserving energy conversion 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 diamond cantilever microphone offers high sensitivity, wide bandwidth, and resistance to electromagnetic interference, suitable for detecting weak acoustic signals in harsh industrial environments with excellent chemical stability.
Implementation Method 1
The acoustic signal acts on the diaphragm, causing elastic deformation of the diaphragm surface
Implementation Method 2
Incident light enters through the optical fiber, where it undergoes multiple reflections between the end face of the optical fiber and the inner side of the rigid diaphragm, thereby leading to F-P interference. The acoustic signal acts on the diaphragm, causing elastic deformation of the diaphragm surface. This deformation leads to a phase change in the inner interference light, thus converting the acoustic signal into an optical signal.
Implementation Method 3
The interference light can be received by a highly sensitive photoelectric detector, and after optical signal collection, it is converted into a voltage signal output
Implementation Method 4
preparing a diamond diaphragm by setting silicon as a substrate in a chemical vapor deposition device; adjusting the heating temperature and pressure of the chemical vapor deposition device; introducing methane and hydrogen for the chemical vapor deposition reaction; obtaining a diamond polycrystalline thin film on the silicon substrate
Data Source
AI summary
This invention unveils an optical microphone utilizing diamond cantilevers and its associated acoustic sensing system. The core component is a diamond cantilever, featuring a diamond diaphragm with a centrally located U-shaped groove. The manufacturing process involves several key steps: initially preparing the diamond diaphragm using silicon in a chemical vapor deposition setup, where methane and hydrogen are reacted under specific temperature and pressure conditions to form a diamond polycrystalline film on the silicon. This film is then separated from the substrate to create the diaphragm. Subsequently, a U-shaped groove is crafted on the diaphragm by applying a dry etching template and etching, resulting in the formation of the diamond cantilever, with a thickness ranging from 10 to 100 μm. This method establishes a novel approach to creating sensitive and durable optical microphones.