Wearable Ultrasonic Patch with Piezopolymer on Active Pixel Circuitry

Wearable sensors for biomarker monitoring enable continuous, non-invasive health tracking. Ultrasound imaging offers access to deep tissue, allowing real-time monitoring of arterial hemodynamics and estimation of blood pressure. One of the key requirements for an ultrasound wearable patch is flexibility. In this paper, we propose a thin, flexible ultrasonic sensor consisting of piezopolymer on two-dimensional active receiving pixel array. The sensor stack is primarily composed of polymer materials and conforms to tissue for wearable use cases. A soft compliant coupling layer attaches the sensor patch to tissue and thus there is no external pressure applied by sensor on tissue which often is a source of blood pressure measurement uncertainly. The active pixels of the sensor include polysilicon-based thin-film transistors (TFTs) circuits. The device employs a plane wave transmit signal and 2D ultrasonic image is sampled by pixel array. A customized ASIC then reads the image which is used to create 3D images of tissue structure including vascular structure and its dynamics. The multimodal sensor also supports other sensing methods including passive piezoelectric bending, piezoelectric sensing, piezo-resistive force sensing and temperature sensing.