[Back]

A. Schröder, S. Harasek, M. Kupnik, M. Wiesinger, E. Gornik, E. Benes, M. Gröschl:
"A Capacitance Ultrasonic Transducer for High-Temperature Applications";
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 51 (2004), 7; 895 - 906.

This paper introduces a novel ultrasonic capacitance
transducer for operation at elevated gas temperatures
of several hundred degrees Celsius. The transducer
design is based on a metallic membrane foil and a backplate
made of an electrically conducting substrate coated
with an insulation layer. Guidelines are given for selecting
suitable materials for the membrane foil, the backplate substrate,
and the coating. Manufacturing techniques applied
for fabrication of di?erent transducer types are described in
detail. Transducers tested were composed of titanium substrates
with insulation layers of silicon nitride or of silicon
substrates with silicon oxide coatings. Experimental setup
and test procedures are described. Results of transducer
characterization and performance tests at elevated temperatures
are presented and discussed. Transducer functionality
is proven for air temperatures of up to 500