A quasi-digital pressure/touch sensor prototype for orbital targets contact event monitoring

This paper presents a sensorized belt with four fully integrated pressure-touch sensors. We propose a very-low complexity sensor able to measure a pressure variation (up to 4 MPa) and to identify with accuracy a contact event at around 10 kPa. The overall pressure/touch sensor integrates a transducer, based on piezo capacitive material, coupled with a read-out circuit designed around a ring-oscillator. This converts the capacitance variation of the transducer into a quasi-digital signal characterized by a frequency range of 36.3-270 kHz with a very low standard deviation (2.3 kHz) and a sensitivity of 2.2 Hz/Pa. The tight integration of the electronics with the transducer results in a very compact all-in-one sensor system (overall size is 20 mm × 20 mm × 10 mm). Further, a major benefit of a low complexity design is the low power consumption, measured to be ~370 μW. Based on a quasi-digital approach (event-driven), the system is well suited for impulse-based wireless communication.