A Lamb wave electrostatic voltage sensor

Abstract

Lamb-wave electrostatic voltage sensors have been fabricated using planar technology incorporating a standard interdigital transducer (IDT) array (for generation and detection of the Lamb waves) and a capacitative electrode placed on each side of the sensor substrate in the region of wave propagation (for applying the DC potential). The Lamb waves/modes generated for substrate thicknesses of 50, 102, and 254 mu m were identified using theoretical dispersion curves. The modes were of both the antisymmetric and symmetric variety. The electrostatic voltage sensitivity, as measured in a SAW (surface acoustic wave) oscillator configuration, was double that of an equivalent Rayleigh device. Insertion losses, short- and long-term oscillator stability, and oscillator thermal sensitivity are reported.<>