Selective Laser Sintering and Graphitization for Mono-Matrix Unibody Fabrication of Integrated Stereo-Circuit and...

Wearable integrated electronic devices for biomedical, robotics, and sensing applications require greater compactness and functional complexity while maintaining wearability. However, seamlessly integrating electronic and microfluidic components remain challenging due to fabrication heterogeneity, material mismatches, and complex assembly requirements. In this study, we present an innovative selective laser sintering and graphitization (SLSG) 3D printing technology that enables seamless integration of 3D circuits (stereo-circuits) and 3D fluidic channels (stereo-fluidics). SLSG achieves unibody, autonomous mono-matrix fabrication through adaptive photonic modulation of carbon-rich precursors (e.g., polyetheretherketone (PEEK) powder), simultaneously creating insulating sintered structures and conductive graphitized patterns with conductivity up to 1,895 S/m, yielding 7.64-fold higher electrochemical performance than classic glassy carbon electrodes (GCEs). Using SLSG, we fabricated a watch-type wearable unibody multimodal microfluidic biosensor (UMMB) with integrated electrochemical biosensors for on-body sweat metabolite monitoring. UMMB incorporates stereo-circuits for sensing and signal routing, plus stereo-fluidic channels for sweat respiration, achieving effective lactate and glucose sensing. The device demonstrates excellent sensitivities of 29.43 and 16.86 µA/mM for detecting lactate and glucose, respectively, while exhibiting nondetectable interference or circuit-fluidic crosstalk. This novel SLSG 3D printing technology introduces a transformative unibody approach to fabricate multifunctional bioelectronic-fluidic platform for integrated point-of-care devices, wearable sensors/biosensors, actuators, advanced theranostics, and personalized biomedical devices.