Capacitive MEMS sensors and actuators require a DC bias for operation, but this bias inadvertently stiffens the movable element, raising resonance, narrowing bandwidth, and reducing sensitivity. Existing fixes include multilayer stacks, sacrificial layers, or closed-loop feedback, but these add cost, parasitics, and noise, while tighter gap tolerances increase pull-in risks. The result is a persistent trade-off between sensitivity, manufacturability, and device stability that limits next-generation MEMS performance.
This invention patterns interdigitated comb electrodes and a suspended beam in a single conductive silicon layer on an SOI wafer. Two lower-voltage “attractive” electrodes supply sensing bias, while higher-voltage “repulsive” side electrodes generate an opposing electrostatic force. The grounded bulk silicon shapes the fields to create a net negative electrostatic spring that reduces natural frequency and amplifies motion. Capacitive readout confirms a >1200% displacement gain and ~35% resonance reduction, achieved using standard planar lithography without sacrificial layers.
• >6× sensitivity boost without added thermal noise
• Resilient to pull-in, enabling higher usable bias and wider dynamic range
• Single-layer SOI process lowers fabrication cost and complexity
• Electrically tunable stiffness allows on-demand bandwidth/gain control
• Reduced parasitics vs. multilayer designs, improving SNR and stability
• Compact CMOS-compatible layout simplifies integration and packaging
• US Provisional Patent Application 63/751,591 – Filed January 30, 2025
Lab validated – Prototype testing demonstrated >1200% displacement gain and ~35% resonance reduction under controlled conditions. TRL ~4.
This technology is available for licensing.
Well-suited for MEMS microphone, sensor, and actuator manufacturers seeking scalable, CMOS-compatible designs that deliver greater sensitivity and lower noise without added complexity.
Prototype test data, MEMS process flow details, and performance characterization available upon request.