Additive manufacture of impedance matching layers for air-coupled ultrasonic transducers

A key problem in designing an efficient ultrasonic transducer for operating in a low acoustic impedance medium such as air is the large impedance mismatch between the active piezoceramic material and the load medium. While acoustic matching layers can be added to the face of the piezoceramic, the associated manufacturing difficulties and reliability can impact upon the cost and longevity of the resultant transducer. This paper presents some preliminary investigations conducted using an additive manufacturing technique, to develop a new material system for matching layer fabrication for air-coupled ultrasonic transducers. Results to date are very encouraging, and could result in a robust, reproducible, economical and improved fabrication method for air-coupled transducers.