MEMS Proof Mass in 3D Cavity for TWS Earphone Integration
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Solution Overview
Problem
Current MEMS accelerometer designs are too thick and large to be effectively integrated into true wireless stereo (TWS) earphones, which require a minimized form factor to handle voice vibrations in noisy environments.
Innovation Solution
A micro-electromechanical system (MEMS) device with a minimized proof mass that occupies a smaller area compared to the suspended structure, allowing for a more compact design suitable for TWS earphones. The device includes a composite substrate, a cavity, a piezoelectric stacking structure, and a proof mass, where the proof mass is formed in the cavity and connects to the piezoelectric stacking structure, with a coverage area less than half of the suspended region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional MEMS accelerometer design is used, then the device can sense voice vibrations, but the device becomes too thick and large for TWS earphones
Solution Approach 1:
The patent transitions from a planar MEMS structure to a three-dimensional cavity-based design. The proof mass is positioned within a cavity formed in the substrate, allowing the suspended structure to extend vertically into the cavity space. This dimensional change enables compact integration while maintaining the functional area needed for vibration sensing, effectively reducing the device's footprint for TWS earphone integration.
Solution Approach 2:
The patent implements nesting by placing the proof mass inside the cavity, which is itself formed within the substrate structure. The suspended structure connects the proof mass to the substrate, creating a nested configuration where components are integrated within the available space. This nesting approach maximizes the use of vertical space while minimizing the horizontal footprint, enabling compact device design.
2Volume of moving object
If the proof mass coverage area is reduced to minimize device size, then the device becomes compact for TWS earphones, but the sensor accuracy may be compromised
Solution Approach 1:
The patent applies local quality by concentrating the proof mass coverage area to less than half of the suspended region area, rather than uniformly distributing mass. This localized concentration optimizes the mass distribution to enhance vibration sensing sensitivity in critical areas while minimizing overall device size. The non-uniform mass distribution maintains sensing accuracy by focusing mass where it most effectively detects voice vibrations.
Solution Approach 2:
The patent changes the geometric parameter of the proof mass, specifically setting its coverage area to less than 50% of the suspended region area. This parameter optimization balances the trade-off between device compactness and sensing accuracy. By carefully controlling the proof mass area relative to the suspended structure, the design achieves miniaturization while preserving the mechanical sensitivity required for voice vibration detection in noisy environments.
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 compact MEMS device enables efficient voice vibration sensing in TWS earphones, even in noisy conditions, by providing a smaller, more accurate proof mass that maintains sensor accuracy without compromising the device's size.
Implementation Method 1
a piezoelectric stacking structure and a proof mass, with the piezoelectric stacking structure having a suspended region over the cavity
Data Source
AI summary
A method of forming micro-electromechanical system (MEMS) device, the MEMS device includes a composite substrate, a cavity, a piezoelectric stacking structure and a proof mass. The composite substrate includes a first semiconductor layer, a bonding layer and a second semiconductor layer from bottom to top. The cavity is disposed in the composite substrate, and the cavity is extended from the second semiconductor layer into the first semiconductor layer and not penetrated the first semiconductor layer. The piezoelectric stacking structure is disposed on the composite substrate, with the piezoelectric stacking structure having a suspended region over the cavity. The proof mass is disposed in the cavity to connect to the piezoelectric stacking structure.