β-Phase-Rich Laser-Induced Hierarchically Interactive MXene Reinforced Carbon Nanofibers for Multifunctional Breathable Bioelectronics

Hierarchically interactive 3D-porous soft carbon nanofibers (CNFs) have great potential for wearable bioelectronic interfaces, yet 90% of CNFs are derived from expensive polyacrylonitrile associated with complex production methods. Here, another cost-effective fluoropolymer, poly(1,1-difluoroethylene) (PDFE), is introduced to investigate its transition chemistry and structural evolution over laser-induced carbonization (LIC). The impregnation of Ti3C2Tx-MXene followed by dehydrofluorination is believed to be crucial to enhance the beta-phase and reinforce PDFE-based nanofibers. It is explored that the beta-phase of the dehydrofluorinated MXene-PDFE nanofibers is converted into an sp(2)-hybridized hexagonal graphitic structure by cyclization/cross-linking decomposition during LIC. Remarkably, this approach generates laser-induced hierarchical CNFs (LIHCNFs) with a high carbon yield (54.77%), conductivity (sheet resistance = 4 Omega sq(-1)), and stability over 500 bending/releasing cycles (at 10% bending range). Using LIHCNFs, a skin-compatible breathable and reusable electronic-tattoo is engineered for monitoring long-term biopotentials and human-machine interfaces for operating home electronics. The LIHCNFs-tattoo with high breathability (approximate to 14 mg cm(-2) h(-1)) forms compliant contact with human skin, resulting in low electrode-skin impedance (23.59 k Omega cm(2)) and low-noise biopotential signals (signal-to-noise ratio, SNR = 41 dB). This finding offers a complementary polymer precursor and carbonization method to produce CNFs with proper structural features and designs for multifunctional biointerfaces.