A Hybrid CMOS-Polyimide Adaptive Force Radiometric Array with 3-5 GHz Wireless Connectivity

To bridge the gap between force sensing technologies and wireless communication systems, this paper introduces a hybrid force spectrometer array with direct analog force-to-radio-frequency (RF) radiation conversion. The design comprises of a thin-film force sensor array, flexible printed circuit board, an array of four class-D low-power voltage-controlled oscillators in 65 nm CMOS technology for voltage-to-frequency conversion, and a broadband multi-port loop antenna for RF radiation. Class-D VCOs consume less than 2 mW of DC power and the system presents a linear force-to-frequency relationship. The measured spectrometer can achieve a force dynamic range of 105 N, a resolution of 0.1 N, and confirmed wireless connectivity more than 5 meters (limited by the lab dimensions).