Ultra‐Deformable and Tissue‐Adhesive Liquid Metal Antennas with High Wireless Powering Efficiency

Abstract

Flexible and stretchable antennas are important for wireless communication using wearable and implantable devices to address mechanical mismatch at the tissue–device interface. Emerging technologies of liquid‐metal‐based stretchable electronics are promising approaches to improve the flexibility and stretchability of conventional metal‐based antennas. However, existing methods to encapsulate liquid metals require monolithically thick (at least 100 µm) substrates, and the resulting devices are limited in deformability and tissue‐adhesiveness. To overcome this limitation, fabrication of microchannels by direct ink writing on a 7 µm‐thick elastomeric substrate is demonstrated, to obtain liquid metal microfluidic antennas with unprecedented deformability. The fabricated wireless light‐emitting device is powered by a standard near‐field‐communication system (13.56 MHz, 1 W) and retained a consistent operation under deformations including stretching (>200% uniaxial strain), twisting (180° twist), and bending (3.0 mm radius of curvature) while maintaining a high quality factor (q > 20). Suture‐free conformal adhesion of the polydopamine‐coated device to ex vivo animal tissues under mechanical deformations is also demonstrated. This technology offers a new capability for the design and fabrication of wireless biomedical devices requiring conformable tissue‐device integration toward minimally invasive, imperceptible medical treatments.

Digitally-embroidered liquid metal electronic textiles for wearable wireless systems

“…In comparison to conductive textiles, liquid metal encapsulated with stretchable polymer, such as silicone rubber, can achieve high electrical conductivity and adaptation to mechanical changes 27 – 30 . These unique properties have been leveraged to create stretchable electromagnetic devices such as inductive coils 31 – 33 and radiative antennas 34 – 36 on elastomeric substrates. Recent works also demonstrate liquid metal fibers fabricated by filling liquid metal into polymer fibers for sensing and energy harvesting 37 – 40 .…”

Healable, Recyclable, and Multifunctional Soft Electronics Based on Biopolymer Hydrogel and Patterned Liquid Metal

“…After peeling from the substrate, the HSE still maintains the 3D shape. Return loss ( S 11 ) of the HSE with spiral shape LM line as near field communication (NFC) antenna [ 51 ] is measured by vector network analyzer before and after the thermoforming process, showing no obvious discrepancy in resonant frequency (frequency corresponding to the peak of S 11 ) or signal intensity (Figure 5b).…”

High‐Resolution 3D Printing for Electronics

“…Yamagishi et al fabricated a thin film-based liquid metal injected microfluidic channel antenna with high deformability. [178] The authors formed a coil-shaped silicone sealant microfluidic channel with a channel width of 67 μm, through direct writing on flexible/stretchable Ecoflex substrates which were followed by the injection of gallium-based liquid metal in the microfluidic channel. The proposed wireless light-emitting device is operated by a standard near-field-communication (NFC) system (13.56 MHz) and maintained the same performance under deformations including stretching (>200% uniaxial strain), twisting (180°) and bending (3.0 mm radius of curvature).…”