# Thermo-responsive, on-demand adhesive and tissue-conformal hydrogel electrodes for organ repair and brain-computer interfaces

## TL;DR

A new hydrogel electrode can stick to wet tissues quickly, adjust to body temperatures, and safely detach, making it useful for medical devices like brain-computer interfaces.

## Contribution

A novel hydrogel with thermo-responsive adhesion and tissue-conformal properties for stable bioelectronic interfaces.

## Key findings

- The hydrogel adheres to wet tissues in 5 seconds and withstands pressures over 213 mmHg.
- It enables stable in vivo ECoG and ECG recordings with a low modulus of 41 kPa.
- The material shows high cytocompatibility, low hemolysis, and 90% antibacterial efficiency.

## Abstract

Implantable bioelectronic devices, such as brain-computer interfaces (BCIs), face persistent challenges in achieving stable, rapid, and reversible adhesion on wet tissues due to hydration layers and mechanical mismatch, which can cause interfacial failure and unstable signals. Here, we report a conductive hydrogel interface with tissue-adaptive, temperature-controllable adhesion. The material is synthesized via dynamic co-entanglement of poly(acrylic acid) and poly(lipoic acid) with LA-NHS, establishing a dual physico-chemical anchoring mechanism that enables efficient tissue integration in aqueous environments. The hydrogel penetrates tissue microstructures within 5 s, withstands burst pressures >213 mmHg, exhibits <10 % swelling, ∼2784 % extensibility, and a low modulus of 41 kPa, thereby conforming to soft, irregular surfaces and reducing interfacial mismatch. Its temperature-triggered adhesion allows safe detachment and repositioning without apparent tissue damage, supporting repeated applications. In vivo and ex vivo tests confirm rapid hemostasis in mouse liver and tail injury models, effective sealing of porcine gastric, bladder, and intestinal defects, and stable electrocorticography and electrocardiography recordings. Moreover, the hydrogel demonstrates high cytocompatibility (>90 %), <5 % hemolysis, reactive oxygen species scavenging, and ∼90 % antibacterial efficiency. By integrating rapid wet adhesion, mechanical compliance, electrical functionality, and bioprotective features, this hydrogel provides a versatile platform for next-generation bioelectronic interfaces and soft therapeutic devices.

Image 1

•Dual hydrophilic-hydrophobic network achieves 5 s wet adhesion with <10 % swelling.•Cold-triggered debonding enables non-traumatic removal and repositioning.•Conformal, low-modulus gel records stable in vivo ECoG/ECG signals.•Ionic-liquid/Ag+ doping adds conductivity and ∼90 % antibacterial activity.

Dual hydrophilic-hydrophobic network achieves 5 s wet adhesion with <10 % swelling.

Cold-triggered debonding enables non-traumatic removal and repositioning.

Conformal, low-modulus gel records stable in vivo ECoG/ECG signals.

Ionic-liquid/Ag+ doping adds conductivity and ∼90 % antibacterial activity.