Femtosecond laser direct writing Bombyx mori sericin-based nanocomposites into intrinsically soft wearable micro-/nano-electronics

Intrinsically flexible micro-/nano-electronics are increasingly in demand for wearable/implantable bio-machine interfacing optical electronics and soft robots. In this work, we developed intrinsically flexible and soft wearable micro-/nano-electronics by femtosecond laser direct writing Bombyx mori sericin-based nanocomposites. Sericin was used as the biomacromolecular reductant to photo-reduce metal ions into nanoparticles and the molecular matrix for in situ nano-compositing. The two/three-dimensional fabrication realized ∼350 nm minimum line width, customizable Young's modulus (∼0.22-3.35 GPa in air), and nano-scale morphology (∼12.1 nm average roughness). The electrical percolation and adjustable conductivity up to 10⁵ S m^-1 were studied. Within the sericin/Ag-nanocomposite percolation-threshold range, a miniaturized electro-mechano-sensor was prototyped with gauge factors (GF ∼ 16.95) and linearity (R² ∼ 0.996), short response/recovery time (200 ms/120 ms), low detection limit (∼0.06% deformation) and power consumption (<0.1 mW), and remarkable intrinsic flexible performances (e.g., ∼10⁴ time outward bendings). Cell/skin biocompatibilities and detections of human muscle/joint movements and sounds were demonstrated, promising its practical potential towards in vivo or in vitro bio-integrated electronics.