Air-coupled transducer with a hollow glass microspheres filled epoxy resin matching layer

The main problem among the developing of the thickness mode piezoelectric air-coupled ultrasonic transducer is the acoustic impedance mismatch between piezoelectric plate and air. To solve this problem, a kind of porous composite material is introduced as the matching layer. The acoustic parameters measurement methods of the hollow glass microspheres filled epoxy resin composite material is studied in this article. On this basis, a pair of thickness mode air-coupled transducer with hollow glass microspheres filled epoxy resin as the matching layer is manufactured. A transmitting receiving testing system using this pair of transducers is built, the uplifting of receiving signal voltage peak-to-peak value is measured and compared with theoretical calculations.