Feasibility of Energy-Autonomous Wireless Microsensors for Biomedical Applications: Powering and Communication

Abstract

In this review, biomedical-related wireless miniature devices such as implantable medical devices, neural prostheses, embedded neural systems, and body area network systems are investigated and categorized. The two main subsystems of such designs, the RF subsystem and the energy source subsystem, are studied in detail. Different application classes are considered separately, focusing on their specific data rate and size characteristics. Also, the energy consumption of state-of-the-art communication practices is compared to the energy that can be generated by current energy scavenging devices, highlighting gaps and opportunities. The RF subsystem is classified, and the suitable architecture for each category of applications is highlighted. Finally, a new figure of merit suitable for wireless biomedical applications is introduced to measure the performance of these devices and assist the designer in selecting the proper system for the required application. This figure of merit can effectively fill the gap of a much required method for comparing different techniques in simulation stage before a final design is chosen for implementation.

Silicon-Integrated High-Density Electrocortical Interfaces

“…There are three primary methods for powering an implanted device: employing a battery, harvesting energy from the environment, and delivering power transcutaneously via a wireless power transmitter [125], [126]. A natural first choice would be a battery, as they have been extensively used in other implantable applications such as pacemakers.…”

“…In addition, governmental regulatory agencies limit the amount of power that can be dissipated in tissue for safety reasons-the U.S. Federal Communications Commission (FCC) sets a specific absorption rate (SAR) of less than 1.6 W/kg, for example. For these reasons, conventional transcutaneous power transfer links operate in the low-megahertz range, often at the 6.78-and 13.56-MHz ISM bands [125], [144], [145].…”

“…), farfield radios can be quickly adopted for robust operation [122]. However, even state-of-the-art low-power radios consume 9 1 nJ/b [125], [164], which is order-ofmagnitude larger than what typical ECoG recording IMDs require.…”

“…[168] In addition, antennas for this type of transmission do not need to be large. However, there are a couple of critical reasons against their usage for IMDs [125]. Foremost, their peak transmission power is large due to the inherently duty-cycled nature of IR-UWB transmitters.…”

Compactmulti‐frequencysystem design forSWIPTapplications

“…23 For example, 1-10 Mbps is needed for the brain-machine interfaces and wireless capsule endoscope, while retinal implants require a data rate of 40 Mbps. 24 Hence, there is a pressing need to develop multi-band WPT systems with enhanced bandwidth to facilitate the required data transmission. By nature, the employment of coils provides a very narrow-band which limits the achievable data rate.…”