Piezoelectric transducer design for simultaneous ultrasonic power transfer and backscatter communication

Ultrasonic waves can transfer power and data to sensors and devices deployed to traditionally inaccessible locations, such as inside the human body or deep in the ocean, eliminating the need for battery replacement. In ultrasonic power and data transfer systems, a piezoelectric transducer converts incident ultrasonic waves to useful electric power while transmitting data by modulating its reflected signal through backscatter communication. Existing approaches rely on reflecting a portion of the incident power to communicate, reducing the harvested power. This work realizes uninterrupted power harvesting with simultaneous backscatter communication through frequency multiplexing. A piezoelectric transducer is first designed and tested experimentally for high sensitivity and high bandwidth operation through low-loss broadband acoustic and electrical impedance matching. The transducer achieved 70% bandwidth at 1 MHz with a 10 dB difference between reflecting and absorbing incident ultrasonic waves. A frequency multiplexing technique is then developed to separate power and data into different frequency bands achieving simultaneous operation. The technique extends the range and bandwidth of ultrasonically powered devices such as biomedical implants and ocean monitoring sensors.