Zero-Power Ultrasonic Wakeup Receiver Based on MEMS Switches for Implantable Medical Devices

Abstract

This article demonstrates, for the first time, a zero-power ultrasonic wakeup receiver for intra-body communication with Implantable Medical Devices (IMDs). The system is based on a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${10} \times {10}$ </tex-math></inline-formula> Piezoelectric Micromachined Ultrasonic Transducer (pMUT) array, a zero-power 500 nm gap MEMS plasmonic switch, a low-leakage CMOS load-switch, and an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ad hoc</i> sensing circuit. An ultrasonic signal of 10 mVpp is received by the pMUT array at a distance of 5 cm and brings the MEMS switch from the OFF-state (1 pA) to the ON-state ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$20~{\mu } \text{A}$ </tex-math></inline-formula> ) when biased at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$9.09~{V}_{\text {DC}}$ </tex-math></inline-formula> . This small current then wakes up the load-switch (< 10 nW when off), which powers up the sensing circuit to decode the pMUT signal. The system is demonstrated in a tissue phantom, making it ideal for intrabody communication.