Wireless Reading of Additively Manufactured Galinstan-based Sensor using a Polarimetric Millimeter-wave Radar Imaging Technique

A polarimetric millimeter-wave radar imaging technique is proposed to wirelessly read a novel additively manufactured passive sensor composed of a microfluidic channel filled with liquid metal Galinstan. Very high variation of the radar-cross section of the sensor to small variations of the level of Galinstan in the channel is obtained. Indeed, at the radar-to-sensor distance of 2.4m, the measured radar echo level of the sensor varies by 4.5dB when the level of Galinstan changes by 1mm. This sensitivity is higher than previously reported in the Literature for wireless and passive sensors of the same class.