The operation of a novel monolithic sapphire transducer from room temperature to cryogenic temperature is presented. The transducer is a microwave sapphire resonator that senses the motion of internal acoustic resonances through the interaction between electric and acoustic fields. The system is noncontacting and has low mechanical and electrical losses. Also, the microwave characteristics of sapphire are used as an inherent temperature sensor. High mechanical quality factors of 10(8) and 4.5 x 10(8) were attained at 300 and 4 K, respectively. (C) 2000 American Institute of Physics. [S0034-6748(00)03707-2].