# Biointegrated Conductive Hydrogel for Real-Time Motion Sensing in Exoskeleton-Assisted Lower-Limb Rehabilitation

## TL;DR

A new hydrogel was developed that can both protect wounds and sense motion during lower-limb rehabilitation with exoskeletons.

## Contribution

A biointegrated hydrogel combining sensing and therapeutic properties for exoskeleton-assisted rehabilitation.

## Key findings

- The CPSD hydrogel shows strong antioxidant, antibacterial, and biocompatible properties.
- It enables stable motion and electromyographic sensing during dynamic rehabilitation.
- The hydrogel supports closed-loop systems by combining wound protection with real-time monitoring.

## Abstract

What are the main findings?

A multifunctional CPSD composite hydrogel was developed by integrating conductive PEDOT:PSS and dopamine-functionalized alginate into a carboxymethyl chitosan matrix.

The hydrogel exhibits strong antioxidant, antibacterial, and biocompatible properties with stable adhesion under dynamic exoskeleton-assisted rehabilitation.

What are the implications of the main findings?

The CPSD hydrogel enables simultaneous wound protection and real-time lower-limb motion sensing.

This work provides a foundation for closed-loop wearable rehabilitation systems that combine bioelectronic sensing with therapeutic functionality.

Chronic lower-extremity wounds in patients undergoing exoskeleton-assisted rehabilitation require materials that can both protect tissue and enable real-time physiological monitoring. Conventional dressings lack dynamic sensing capability, while current conductive hydrogels often compromise either adhesion or electronic performance. Here, we present a biointegrated hydrogel (CPSD) composed of carboxymethyl chitosan (CMCS) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) forming the conductive backbone, integrated with dopamine-functionalized sodium alginate (SD); the network is assembled via electrostatic complexation and carbodiimide (EDC/NHS)-mediated covalent crosslinking. The resulting hydrogel exhibits a dense, tissue-conformal porous network with tunable swelling, stable mechanical integrity, and high photothermal conversion efficiency. In vitro assays confirmed potent antioxidant activity, strong antibacterial performance (>90% under near-infrared), and excellent cytocompatibility and hemocompatibility. CPSD shows bulk conductivity ~1.6 S·m−1, compressive modulus ~15 kPa, lap-shear adhesion on porcine skin ~9.5 kPa, and WVTR ~75 g·m−2·h−1, supporting stable biointerfaces for motion/sEMG sensing. Integrated into a lower-limb exoskeleton, CPSD hydrogels adhered securely during motion and reliably captured electromyographic and strain signals, enabling movement-intent detection. These results highlight CPSD hydrogel as a multifunctional interface material for next-generation closed-loop rehabilitation systems and mobile health monitoring.