Electrically functionalized body surface for deep-tissue bioelectrical recording

TL;DR

This paper introduces a novel, spray-coated, biocompatible nanosheet film on the body surface that significantly improves deep-tissue bioelectrical signal monitoring by reducing impedance and motion artifacts.

Contribution

It presents a new method for creating conformal, high-performance, low-impedance bioelectrical interfaces directly on the body surface using ambient-condition spray coating of nanosheets.

Findings

Nearly two orders of magnitude lower contact impedance compared to traditional electrodes.

Substantially reduced motion artifacts during body movements.

Reliable extraction of deep-tissue bioelectrical signals from irregular surfaces.

Abstract

Directly probing deep tissue activities from body surfaces offers a noninvasive approach to monitoring essential physiological processes1-3. However, this method is technically challenged by rapid signal attenuation toward the body surface and confounding motion artifacts4-6 primarily due to excessive contact impedance and mechanical mismatch with conventional electrodes. Herein, by formulating and directly spray coating biocompatible two-dimensional nanosheet ink onto the human body under ambient conditions, we create microscopically conformal and adaptive van der Waals thin films (VDWTFs) that seamlessly merge with non-Euclidean, hairy, and dynamically evolving body surfaces. Unlike traditional deposition methods, which often struggle with conformality and adaptability while retaining high electronic performance, this gentle process enables the formation of high-performance VDWTFs directly on the body surface under bio-friendly conditions, making it ideal for biological applications. This results in low-impedance electrically functionalized body surfaces (EFBS), enabling highly robust monitoring of biopotential and bioimpedance modulations associated with deep-tissue activities, such as blood circulation, muscle movements, and brain activities. Compared to commercial solutions, our VDWTF-EFBS exhibits nearly two-orders of magnitude lower contact impedance and substantially reduces the extrinsic motion artifacts, enabling reliable extraction of bioelectrical signals from irregular surfaces, such as unshaved human scalps. This advancement defines a technology for continuous, noninvasive monitoring of deep-tissue activities during routine body movements.