An ultrasound imaging system exploiting transducers and multiplexers on a flexible substrate together with a log-delta CMOS ADC

Ultrasound (US) imaging is a fundamental tool in healthcare for the diagnosis of diverse conditions. Wearable, flexible ultrasound patches could expand the scope of US imaging to continuous, at-home monitoring without professional intervention, but require scaling to large numbers of transducer elements. This poses challenges in interconnect density, power consumption, and data bandwidth. To improve interconnect density, we present the first integration of flexible ultrasound transducers with flexible a-IGZO thin-film transistor (TFT) multiplexing electronics. In the Si CMOS readout chip, a new circuit technique cuts front-end power, while a log-delta ADC compresses data efficiently. Our system achieves an 8× reduction in required front-end circuitry and a 42% decrease in front-end power. The data needed to describe the ultrasound image are reduced five-fold, decreasing data transmission power by the same factor. These advances bring the vision of wearable high-density, large-area ultrasound imaging patches for monitoring one step closer.