SAW signal conditioner-based dynamic capacitive sensor for high-speed gap measurement

High-speed gap measurement in the nano/micrometer range presents unique engineering challenges. A signal conditioner is required for capacitive sensors to amplify, denoise, and restrict the bandwidth. In this work, a capacitive sensor was used in combination with a SAW device that serves as a signal conditioner. The proposed system provides 2.75 MHz bandwidth through amplitude modulation using the center frequency of the SAW device as a carrier signal and has outstanding signal conditioning capabilities. Construction and characterization of a SAW-based capacitive gap sensor to measure a 200 Hz gap frequency are described.