Ultrasoft and Ionically Conductive Bottlebrush elastomer for bioelectronics

Siddhartha Challa, Pengfei Xu, Shaojia Wang, Xinyu Liu

In preparation: Advanced Functional Materials (AFM)

Biological tissues are soft and ionically conductive, but many tools that interact with them are composed of materials that are much stiffer and electronically conductive. Bottlebrush elastomers (BBEs) are ultra-soft but not conductive. Adding ionic liquid to BBEs could provide them with ionic conductivity while maintaining ultra-softness. The lowest Young’s modulus achieved is 1.3 kPa and the highest conductivity is 1.7 mS/cm. The PEG/IL BBE is hygroscopic and the IL could leak from the BBE. A hydrophobic IL could be copolymerized with the BBE to address this limitation. The Young’s modulus and charge carriers of the PEG/IL BBE match those of biological tissues. Our BBE is softer than most reported dry conductive elastomers. The material’s improved properties are beneficial for bioelectronics applications.