US Patent 9,166,141 granted to DVX, LLC and licensed exclusively by Arterium Medical, LLC.
This patent describes how to increase the ultrasound energy from piezopolymer (thin film) transducers by the use of a matching layer in a way that can be manufactured cheaply.
Arterium Medical believes that this patent limits others from making a low cost ultrasound sensor with high energy efficiency. This uniquely enables Arterium's disposable thin film ultrasound bio-sensor.
Others have reported that piezopolymer materials could not produce usable levels of ultrasound energy.