Abstract: A coating providing high abrasion and chemical resistance composed of a barrier layer from vanadium, molybdenum, niobium, tantalum and the like, and an outer layer of diamond-like carbon. The coating is especially applicable for acoustic wave device (AWD) based sensors, and for passivating an electrode such as an electrode deposited on the AWD sensing area. The coating provides excellent mechanical and acoustical characteristics for coating acoustic wave devices allowing the sensor to operate in harsh environments.

Abstract: A composite acoustic wave device (AWD) which is adapted for operation at high ambient pressures is provided. The AWD comprises two piezoelectric plates in back to back relationship, with electrodes disposed between the plates. The plates are bonded so as to neutralize the effects of external pressure. Further disclosed is a sensor utilizing the AWD and methods for utilizing such AWD for physical measurements in high pressure environments. An optional cavity formed between the piezoelectric plates offers the capability to measure the pressure and to further neutralize the residual effects of the pressure on measurement accuracy.