Bulk acoustic wave (BAW) sensors for liquid level measurements

A method for sensing at least one level parameter of at least one liquid in a tank. At least one bulk acoustic wave (BAW) sensor is positioned inside the tank. Electrodes of the BAW sensor are at least switchably connected to a positive feedback loop across an amplifier to provide an electronic oscillator. At least one acoustic viscosity measurement is determined from an output of the electronic oscillator, wherein the output of the electronic oscillator is different when the BAW sensor contacts the liquid as compared to different when the BAW sensor contacts air. The level parameter is determined from the acoustic viscosity measurement. System (100) -Tank (110) Electronic Add ress z r-- 170 Array (1 11) - -- 112' Control Unit IDT (112) IDT (113)) 111d--- 112' I DT (112) I DT (113) 111c 1 1 3 '- --- -- -- L - - 112' IDT (112) Readout IDT (113) T it -11Apparatus 113" 101- 112' I DT (113)11a50 9 0113