Miniature Robust High-Bandwidth Force Sensor with Mechanically Amplified Piezoresistive Readout

For fast and accurate force measurements, e.g., sampling the impact of a liquid droplet, a highly sensitive high-bandwidth force sensor is required. High-sensitivity and high-bandwidth are contradictive specifications in recently published force sensors. The miniature force sensor proposed in this paper uses a novel combination of in-plane sensing, mechanical amplification, and piezoresistive readout that overcomes this contradiction. The straight-forward fabrication process consists of three photomasks and uses a single SOI wafer. The sensor has a proven range of 13 mN, a sensitivity of 1.46N
⁻¹
and a bandwidth of 75 kHz. This is the first force sensor in this force range with such a large bandwidth and has the potential to open up a new field of force sensing where high sampling rates and low ranges are crucial.