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 100µm) 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 (13.56MHz, 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.