In Situ Microwave Sensors and Switching Circuit for Oil Slick Thickness Measurement

The measurement of oil slick thickness, although at an early stage, has immense applications in determining the extent and quantity of crude oil accidentally discharged in oceans. In this work, we present the design, development and measurement of sensors and switching circuit that were integrated to form a novel microwave oil spill sensor for the determination of oil slick thickness. We used four ultra-wideband polydimethylsiloxane encapsulated antenna-sensors in a cuboid configuration connected to a customised RF switching circuit comprising of two single pole double throw (SPDT) switches. Each of the SPDT switches were connected to two antennas and a port of the vector network analyser (VNA). We developed an android application on a smartphone to select each of the antenna-sensors for the oil slick thickness measurements. The four antenna-sensors operated in the radiating near-field regions. Crude oil has lower density compared to salted seawater, therefore, it floats on the surface. This enabled the four-sensor antenna array to establish the oil thickness using radio frequency. The simulated and measured transmission coefficients showed the capability of the oil slick measurement sensor and switching circuit to determine the oil slick thickness using a novel contact-based in situ microwave approach.