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

Abstract 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 Ti 3 C 2 T x ‐MXene followed by dehydrofluorination is believed to be crucial to enhance the β‐phase and reinforce PDFE‐based nanofibers. It is explored that the β‐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 Ω 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 ( ≈ 14 mg cm −2 h −1 ) forms compliant contact with human skin, resulting in low electrode‐skin impedance (23.59 k Ω 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.