Development of a wideband medical ultrasonic linear array transducer with a double-sided FPCB

Abstract

Medical ultrasound transducers are being used to acquire medical image information from a patient. In order to acquire high-quality images, studies have been conducted to improve the performance of the transducer. Among them, the high acoustic impedance de-matching layer is effective in improving the sensitivity and bandwidth of the transducer using the backward reflected wave. First, the performance trend of the transducer according to the thickness of the acoustic de-matching layer was analyzed through theoretical calculation and finite element method. It was confirmed that the sensitivity and bandwidth of the transducer increased by adjusting the time delay of the backward reflected wave according to the thickness of the acoustic de-matching layer. Based on the analyzed results, a new structure of a transducer applied with a double-sided FPCB was devised. The time delay of the backward reflected wave was simply controlled by changing the thickness of the polyimide in the FPCB. The bandwidth of the transducer can be increased by changing the thickness of the polyimide in the FPCB. Also, a prototype of a transducer having a designed structure was manufactured and its performance was measured, and it was confirmed that the designed structure was effective in increasing the bandwidth of the transducer.