Design and Application of an EMIMTFSI/GO@PVDF-HFP Flexible Electrode for Triboelectric Nanogenerators

Flexible electrodes with appropriate electrical performance are important for the development of wearable and biointerfaced triboelectric nanogenerators (TENGs), while their local tissue response requires careful assessment for bio-applications. In this work, we designed a novel flexible composite electrode based on a poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) matrix blended with the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI) and doped with graphene oxide (GO). The synergistic effect between EMIM-TFSI and GO facilitates the conformational transformation of PVDF-HFP toward a β-phase-dominated structure and establishes complementary ionic-migration/interfacial-polarization and GO-assisted local charge-transfer/polarization mechanisms for effective signal transmission across a broad frequency range. Cross-scale DFT and FEM simulations elucidate synergistic ionic-electronic transport dynamics and provide a framework for interpreting composite-electrode electrical performance. The Ecoflex/PDMS-encapsulated TENG equipped with this flexible electrode generated an open-circuit voltage of ∼4 V and maintained electrical output after water immersion and during cycling under the tested conditions. Preliminary in vivo observations provided descriptive evidence of a short-term local tissue response, and active TENG stimulation elicited measurable evoked CMAP responses, although the amplitudes were lower than those obtained with conventional electrical stimulation under the tested conditions. This work presents a proof-of-concept flexible bioelectronic interface for self-powered peripheral nerve stimulation.