Tissue-Interfaced Electronics for Directing Biological Functions

Integration of flexible electronics into the living system is expected for advancing medical diagnostics and therapeutics. Such devices should be seamlessly conformed to the physical and mechanical environment of living body, in which acquired biosignals are expected to be transmitted wirelessly to external device. In this regard, we envisage the development of tissue-interfaced electronics for wearable and implantable applications based on polymer nanosheet technology. The polymer nanosheet shows tens- to hundreds-of-nanometer thickness close to the scale of biomembranes, in which various types of polymers (e.g., biodegradable polymers, conductive polymers, and elastomers) are formed into the ultra-thin structure. Free-standing polymer nanosheets showed flexible and adhesive properties derived from their ultra-small flexural rigidity (< 10^-2 nN m). In this talk, polymer nanosheet (or thin film)-based devices are introduced by combining polymer nanosheet and printing technologies with variety of unique inks. A microgravure coater was employed for the preparation of flexible substrates or electrodes, an inkjet printer allowed for the tailor-made design of multielectrode array, and a laser processing machine was used for making the microchannels for insulating the circuit. The ultra-conformable structure has been utilized as tissue-interfaced electronics to direct biological functions in the applications of healthcare and medicine, represented by the wirelessly-powered light emitting device for photodynamic cancer therapy, and the flexible, thin-film neural electrode for diagnosis and treatment of epileptic seizure.