Resonant micro-sensor platform for contact-free characterization of liquid properties

This paper presents a novel resonant micro-sensor platform which is designed to measure the acoustic properties of liquid samples by quantification of ultrasonic waves reflected from and transmitted through the liquid sample. By avoiding the direct contact of the liquid with the resonator, significant losses due to liquid loading are mitigated and the physical properties of various fluids, including viscous samples, can be determined without adversely affecting the resonator performance. Devices have been fabricated and tested, achieving quality factors up to 6000 in air at 112MHz and the results show that the output signals measured from the device (i.e. the resonator Q/vibration amplitude and the amplitude of the signal passing through the liquid) are sensitive to the properties of the liquid under test.