Love wave based ice sensor

This paper presents the conceptual design, fabrication and experimentation of a Love wave based acoustic ice sensor for sensing the phase change from liquid water to solid ice. The sensing of this transition is made possible by the shear horizontal nature of Love waves, utilizing it's damped to undamped nature during the transition from water to ice respectively. A guiding layer of SiO2 of thickness 3.2 microns deposited via Plasma Enhanced Chemical Vapor Deposition (PECVD) of Tetramethlysilane acts as the wave-guide to guide and propagate the Love waves. Testing is carried out with the water or ice placed directly over the deposited layer and between the Inter Digitated Transducers. Ice sensors with a resonant frequency of 112.5 MHz has been fabricated and tested and it is registered that the resonant frequency shift on the formation of a mono-layer of ice is in the region of 2-4 MHz. The response of the sensor has been presented and discussed. Potential high volume applications include the use of such sensors over airplane wings or bridges of highway systems to detect ice formation and the use of subsequent de-icing circuits to remove the ice early on without causing significant damage.