Highly conductive tissue-like hydrogel interface through template-directed assembly

Abstract

Over the past decade, conductive hydrogels have received great attention as tissue-interfacing electrodes due to their soft and tissue-like mechanical properties. However, a trade-off between robust tissue-like mechanical properties and good electrical properties has prevented the fabrication of a tough, highly conductive hydrogel and limited its use in bioelectronics. Here, we report a synthetic method for the realization of highly conductive and mechanically tough hydrogels with tissue-like modulus. We employed a template-directed assembly method, enabling the arrangement of a disorder-free, highly-conductive nanofibrous conductive network inside a highly stretchable, hydrated network. The resultant hydrogel exhibits ideal electrical and mechanical properties as a tissue-interfacing material. Furthermore, it can provide tough adhesion (800 J/m2) with diverse dynamic wet tissue after chemical activation. This hydrogel enables suture-free and adhesive-free, high-performance hydrogel bioelectronics. We successfully demonstrated ultra-low voltage neuromodulation and high-quality epicardial electrocardiogram (ECG) signal recording based on in vivo animal models. This template-directed assembly method provides a platform for hydrogel interfaces for various bioelectronic applications.

Hydrogels for Flexible Electronics

“…T-ECA denotes an electrically conductive hydrogel with adhesion through template-directed assembly. Adapted with permission under a Creative Commons CC BY License from ref . Copyright 2023 Springer Nature.…”

“…As a result, CP-based CHs have promising applications in flexible bioelectronics, such as neuromodulation and EP signal recording. 24,47 In additional to the above three key properties, hydrogels with multifunctional capabilities can further promote their applications in flexible electronics. These capabilities include, but are not limited to, self-healing, thermal or pH stimuli responsiveness, and biodegradability (Figure 2f).…”

“…A recent study introduced a template-directed assembly method for creating highly conductive and stretchable hydrogels. 47 The doublenetwork configuration comprises the poly(acrylic acid) (PAA) network and assembled PEDOT:PSS network (Figure 5e). The assembled PEDOT:PSS network forms a conductive path in the DN hydrogel, resulting in high, strain-insensitive conductivity.…”

“…These unique advantages, combined with strong adhesion that facilitates an intimately physical interface with biological tissue, can result in low impedance and high charge storage capacity (CSC). As a result, CP-based CHs have promising applications in flexible bioelectronics, such as neuromodulation and EP signal recording. , …”

“…These unique advantages have further promoted their widespread applications in flexible electronics, including CH-based bioelectronics for neuromodulation of peripheral nerves and brain tissue, epidermal electrodes for EP monitoring, and cardiac patches, among others. A recent study introduced a template-directed assembly method for creating highly conductive and stretchable hydrogels . The double-network configuration comprises the poly­(acrylic acid) (PAA) network and assembled PEDOT:PSS network (Figure e).…”