Electronics-free, ultra-low-power, wearable sensor chip for high-frequency electromagnetic field detection

TL;DR

This paper introduces an innovative, electronics-free wearable sensor chip that detects high-frequency electromagnetic fields using a magnetically hybridized liquid crystal microdevice, enabling low-power, in situ detection visible to the naked eye.

Contribution

The work presents a novel, passive, optical EMF sensor based on a magnetically hybridized liquid crystal microdevice, overcoming limitations of existing sensors in power consumption and integration.

Findings

Operates without electronic components or external power.

Provides visible optical response to RF fields.

Potential for in situ electromagnetic field detection.

Abstract

High-frequency electromagnetic fields (EMFs) are increasingly recognized either as environmental risk factors or as tools for electromagnetic attacks, which are difficult to detect in situ. Existing high-frequency EMF sensors face significant limitations related to structural simplicity, integration with mobile technology, and low energy consumption. To address these challenges, we propose a novel sensor concept based on a magnetically hybridized liquid crystal (LC) microdevice. The hybrid LC chip is designed to exhibit an optical response to external radio-frequency fields without the need for electronic components or an external power supply, relying solely on ambient light. Both sides of the chip are covered with polymer-based crossed polarizer films. The chip is filled with flexible matrices containing thermotropic LCs, such as the rod-like 4-cyano-4'-pentylbiphenyl, into which a network of thin ferromagnetic wires is embedded. The resulting field-responsive LC microdisplay operates via a simple magnetothermal mechanism, and its optical response is sufficiently strong to be visible to the naked eye.