Fully Untethered Battery-free Biomonitoring Electronic Tattoo with Wireless Energy Harvesting

Abstract

Bioelectronics stickers that interface the human epidermis and collect electrophysiological data will constitute important tools in the future of healthcare. Rapid progress is enabled by novel fabrication methods for adhesive electronics patches that are soft, stretchable and conform to the human skin. Yet, the ultimate functionality of such systems still depends on rigid components such as silicon chips and the largest rigid component on these systems is usually the battery. In this work, we demonstrate a quickly deployable, untethered, battery-free, ultrathin (~5 μm) passive "electronic tattoo" that interfaces with the human skin for acquisition and transmission of physiological data. We show that the ultrathin film adapts well with the human skin, and allows an excellent signal to noise ratio, better than the gold-standard Ag/AgCl electrodes. To supply the required energy, we rely on a wireless power transfer (WPT) system, using a printed stretchable Ag-In-Ga coil, as well as printed biopotential acquisition electrodes. The tag is interfaced with data acquisition and communication electronics. This constitutes a "data-by-request" system. By approaching the scanning device to the applied tattoo, the patient's electrophysiological data is read and stored to the caregiver device. The WPT device can provide more than 300 mW of measured power if it is transferred over the skin or 100 mW if it is implanted under the skin. As a case study, we transferred this temporary tattoo to the human skin and interfaced it with an electrocardiogram (ECG) device, which could send the volunteer's heartbeat rate in real-time via Bluetooth. Surface biopotentials collected from the human epidermis contain important information about human physiology, such as muscular, heart and brain activities. This includes electromyography (EMG) 1 , Electrocardiography (ECG) 2 , and Electroencephalography (EEG) 3 , among others. The collected data has applications in health monitoring (EMG, ECG, EEG), control of prosthetics 4 or novel forms of wearable human-machine interfaces (EMG) 5,6. Wearable stickers that interface the human epidermis and acquire biopotentials for electrophysiological monitoring can be potentially transformative in digital health, since they would eventually allow a fully wireless and hassle-free data collection from the human body. Unlike traditional "wearable" technology that is composed of several rigid components, these stickers are required to be soft, flexible and stretchable. In this way, they are able to follow the dynamic morphology of the skin and remain attached to the skin during natural human movements. An ideal biomonitoring sticker is as well thin, imperceptible, comfortable and untethered. This can be also in the form of an electrical bandage or a "temporary tattoo" which bonds strongly to the human skin and acquires and transmits the information. During the last five years, some reports on fabrication and applications of ultrathin stretchable electronic films, also called epidermal electronics 7 or electronic...

E-Skin: The Dawn of a New Era of On-Body Monitoring Systems

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Recent Advances in Deformable Circuit Components with Liquid Metal

“…In addition to this, liquid metal is being developed as a deformable electrode for a wide variety of applications including treatment of tumors, [ 70 ] tracking of movement, [ 71 ] resistive switching memory, [ 72 ] superconductors, [ 73 ] coaxial transmission lines, [ 74 ] thermoelectric and triboelectric devices, [ 75,76 ] generating surface acoustic waves, [ 77 ] and acquiring electrophysiological data. [ 78 ]…”

Energy Autonomous Sweat‐Based Wearable Systems

“…( Figure a). Adapting these technologies, a variety of wearable physical, chemical, bio, and optical sensor, [ 3,33,38–43 ] reported in recent years as self‐powered or energy‐autonomous, [ 15,33,44–47 ] can rely on energy generators, [ 21,33,48–51 ] electrochemical energy storage (EESs) devices, [ 3,26,31–35,44,52,53,55–57 ] wireless power technologies, [ 58–60 ] self‐powered sensors, [ 15,33,44–47 ] and hybrid energy system combining both energy generator and EES. [ 61 ] Several review articles have covered these technologies in detail, [ 47,62–68 ] in respective topics such as self‐powered biosensors, [ 69 ] self‐powered medical sensors, [ 70 ] enzyme‐based body‐worn devices, [ 71 ] and other technologies for the environment.…”