Monolithic all-laser fabricated 3D bioelectronic platforms with multilayer hybrid interconnects for multimodal sensing.
Soft, flexible biointerfaces are attractive tools for tracking both biophysical and biochemical signals, yet conventional two-dimensional (2D) planar electrode arrays suffer from limited functional density, and standard metallic interconnects undergo bio-corrosion and oxidation in physiological fluids. Here, we report a monolithic, all-laser manufacturing strategy for 3D-integrated, multilayered flexible biointerfaces based on a structurally doped silver-nanowire/carbon-nanotube-laser-induced-graphene (AgNW/CNT-LIG) hybrid. Produced by a single-instrument, maskless, cleanroom-free workflow, the hybrid conductor attains an intrinsic electrical conductivity of 16.5 ± 1.04 kS/m-a 4.5-fold gain over pristine LIG-with mechanical durability under bending deformation over 2000 cycles. During laser sintering, the porous graphene matrix structurally encapsulates the AgNWs, shielding the metal from the electrolyte and providing markedly superior long-term stability in 1× PBS at 37 °C and against pH-induced corrosion relative to bare AgNW and Cu traces. Vertically stacking the channels into a four-layer architecture interconnected by laser-drilled vias yields ∼5 MΩ/cm interlayer isolation with uniform, reproducible trace resistance, eliminating the lateral crosstalk of coplanar arrays. We demonstrate the platform through three functions on a single architecture: a wirelessly operated flexible circuit, in vivo electroencephalography, and simultaneous electrochemical sensing of glucose (1.167 μA/mM) and lactate (1.081 μA/mM). This scalable route establishes a high-performance foundation for next-generation 3D bioelectronics and implantable closed-loop systems.