Semiconducting Hydrogels for Bioelectronics

Bioelectronics have broad applications in medical treatment, wearable, and implantable devices. The mismatch in mechanical and chemical/biological properties of the interface between conventional bioelectronics and tissues is an important restriction for their practical applications. Ideal bioelectronic devices must be light, thin, flexible, stretchable, and biocompatible. Hydrogels have the most similar mechanical properties to biological tissues. Therefore, if hydrogels can be used to construct electronic devices, it could meet the corresponding needs. In addition, the excellent biocompatibility and easy modification of hydrogels will also provide new functions for electronic devices.

Traditional hydrogels only have ionic conductivity, or have electronic conductivity properties through introducing blended conductors, but they still lack semiconducting properties. Based on cationic conjugated polymer design, we recently proposed a new type of material, “semiconducting hydrogel”. By cross-linking a water-soluble cationic conjugated polymer with counterions or forming a multiple network structure with other hydrogels, semiconducting hydrogels with excellent biocompatibility and bioadhesion have been realized. These hydrogels show good electron mobilities and high on/off ratios, enabling the fabrication of complementary logic circuits and signal amplifiers with low power consumption and high gains. We demonstrate that hydrogel electronics can sense and amplify electrophysiological signals with enhanced signal-to-noise ratios.