Ultrasonic transducer with thermo mechanical excitation and piezoresistive detection

Ultrasonic transducer was fabricated from silicon buckled membrane using a thermo mechanical excitation and piezoresistive detection. The transducer has a 4 mm square silicon membrane, buckled with an initial deflection of 20 /spl mu/m, actuated by dynamically heating an aluminium ring layer, 3 /spl mu/m thick, with a polysilicon ring resistor. Detection is made by measuring the piezoresistive component in the polysilicon layer impedance.