27.7 A 30.5mm³ fully packaged implantable device with duplex ultrasonic data and power links achieving 95kb/s with <10⁻⁴ BER at 8.5cm depth

Abstract

The next generation of implantable medical devices focuses on minimally invasive miniaturized solutions that operate reliably at large depths, provide duplex communication for closed-loop therapies, and enable multi-access for a network of implants to gather information or provide systemic interventions. Using ultrasound (US), power and data can be efficiently transferred through the body as its wavelength at MHz is comparable to a mm-sized receiver, resulting in improved focusing, coupling, and acoustic-to-electrical conversion efficiency. Furthermore, thanks to the low propagation loss (∼1dB/cm/MHz) and 7.2mW/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> safety limit, several mW of power is obtainable at the receiver, enabling high-power, complicated functionalities.