Cross-Media Wireless Made Easier: Tuning Media Interfaces with Flexible Metasurfaces

TL;DR

RF-Mediator is a programmable metasurface system that dynamically tunes media interfaces to significantly reduce power loss in cross-media wireless communication, enabling more efficient IoT applications beyond traditional air interfaces.

Contribution

This work introduces RF-Mediator, a flexible, programmable metasurface that actively mediates media interfaces to improve wireless transmission across different media.

Findings

Median power gain of 8 dB for air-to-tissue links

Up to 30 dB power gain for cross-media backscatter links

Effective in various cross-media experimental setups

Abstract

Emerging wireless IoT applications increasingly venture beyond over-the-air communication, such as deep-tissue networking for implantable sensors, air-water communication for ocean monitoring, and soil sensing. These applications face the fundamental challenge of significant power loss due to reflection at media interfaces. We present RF-Mediator, a programmable metasurface system placed at media interfaces to virtually mask the presence of the physical boundary. It is designed as a single-layer metasurface comprising arrays of varactor-based elements. By tuning the bias voltage element-wise, the surface mediates between media on both sides dynamically and beamforms towards the endpoint to boost transmission through the interface, as if no media interface existed. The control algorithm determines the surface configuration by probing the search space efficiently. We fabricate the surface on a thin, flexible substrate, and experiment with several cross-media setups. Extensive evaluation shows that RF-Mediator provides a median power gain of 8 dB for air-to-tissue links and up to 30 dB for cross-media backscatter links.