RF Sensor for Adulteration Detection of Liquid Silicone Used in Medical Industry

A metamaterial unit cell based planar RF sensor is employed for the first time to detect the adulteration in medical grade liquid silicone. The proposed sensor is based on an electrically coupled complementary split ring resonator (CSRR) etched on the ground plane of the microstrip line. The basic idea behind adulteration detection using the proposed RF sensor is to estimate the level of adulterant in pure liquid silicone by recording the corresponding change in the resonant frequency/insertion loss of the unloaded device. The basic CSRR sensor is designed using the CST-MWS, and its various parameters are optimized in order to improve the sensitivity at the designed frequency (1.69 GHz). Thereafter, the proposed sensor is fabricated on the commercially available FR-4 substrate to measure the scattering parameters using the network analyzer in order to estimate the resonant frequency and insertion loss of the unloaded sensor. Finally, different volume proportions of various oils are added with pure liquid silicone to emulate the practical adulteration scenario. The resonant frequency and insertion loss of all the samples are recorded to establish the graphical relationship between the measured RF parameters and adulteration in silicone liquids. The proposed methodology helps to develop an integrated RF sensor system for the real-time monitoring of purity of liquid silicone for the medical industry.