Robust Neural Interfaces with Photopatternable, Bioadhesive, and Highly Conductive Hydrogels for Stable Chronic Neuromodulation

Abstract

A robust neural interface with intimate electrical coupling between neural electrodes and neural tissues is critical for stable chronic neuromodulation. The development of bioadhesive hydrogel neural electrodes is a potential approach for tightly fixing the neural electrodes on the epineurium surface to construct a robust neural interface. Herein, we construct a photopatternable, antifouling, conductive (∼6 S cm–1), bioadhesive (interfacial toughness ∼100 J m–2), soft, and elastic (∼290% strain, Young’s modulus of 7.25 kPa) hydrogel to establish a robust neural interface for bioelectronics. The UV-sensitive zwitterionic monomer can facilitate the formation of an electrostatic-assembled conductive polymer PEDOT:PSS network, and it can be further photo-cross-linked into elastic polymer network. Such a semi-interpenetrating network endows the hydrogel electrodes with good conductivity. Especially, the photopatternable feature enables the facile microfabrication processes of multifunctional hydrogel (MH) interface with a characteristic size of 50 μm. The MH neural electrodes, which show improved performance of impedance, charge storage capacity, and charge injection capability, can produce effective electrical stimulation with high current density (1 mA cm–2) at ultralow voltages (±25 mV). The MH interface could realize high-efficient electrical communication at the chronic neural interface for stable recording and stimulation of a sciatic nerve in the rat model.

Orchestrating Asymmetric Surface Functionalities on Hydrogel Stamps where Adhesion Meets Lubrication

“…This copper wire-embedded hydrogel demonstrated its adequate sensitivity for advanced motion sensing, and this design strategy (position tracking functions) could also be applied to other bioelectronics. 48,49 Summarized from the above results, the hydrogels developed in this work hold great potential as a soft platform coupling with multiple desirable functions to meet the terminal requirements in a wide range of healthcare applications.…”

Chemically revised conducting polymers with inflammation resistance for intimate bioelectronic electrocoupling

“… PEDOT:PSS-SB electrode showed improved impedance, charge storage capacity, and charge injection capability and demonstrated efficient stimulating and recording during chronic neuromodulation. [ 183 ] Zwitterionic peptide (sequence EKEKEKE) PEDOT–COOH– EKEKEKE / DNA sensor Human plasma / The DNA biosensor displayed high selectivity and low detection limit. [ 170 ] PEG PPy/GCE-PEG Glassy carbon electrode (GCE): 121.4 Ω; PPy coated GCE (PPy/GCE): 12.4 Ω; PPy/GCE-PEG:498.0 Ω.…”

“…Importantly, it could suppress scar tissue formation by 80% after 4 weeks of subcutaneous implantation. Yang et al [ 183 ] developed a sulfobetaine polymer-modified PEDOT:PSS material and used it to fabricate a novel neural electrode. This device features a low impedance and a large charge storage capacity and a high charge injection capability, enabling effective electrical stimulation at a high current density (1 mA cm −2 ) but an ultralow voltage (±25 mV).…”

Design of Sustainable Self‐Healing Phase Change Materials by Dynamic Semi‐Interpenetrating Network Structure

“…[21] To address this challenge, researchers drew inspiration from semi-interpenetrating network (semi-IPN) polymers where one linear polymer and another crosslinking polymer can interpenetrate each other but still maintain their unique properties to a certain extent. [22][23][24] Based on this unique property, high enthalpy efficiency SSPCMs were prepared. In these semi-IPN based SSPCMs, the polymer chains serving as the phase change component have better mobility in the other crosslinking polymer networks, thereby minimizing the impact on their crystallization performance.…”