Zero-Power Ultrasonic Wakeup Receiver Based on MEMS Switches for Implantable Medical Devices
Flavius Pop, Sila Deniz Calisgan, Bernard Herrera, Antea Risso, Sungho Kang, Vageeswar Rajaram, Zhenyun Qian, Matteo Rinaldi
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.