Permeable Janus cellulose electronics with an intrinsic rear filter enabled by laser-induced graphitization for microfluidic wearable biosensors

Integrating permeable electronics with microfluidics is an emerging strategy to improve the fluid-to-sensor interface in wearable biosensors, while achieving a reliable sample-sensor interface remains challenging. Here, we present an advanced permeable Janus cellulose electronic (PJCE) combining cellulose-derived laser-induced graphene (cLIG) electrodes with an intrinsic rear filter. PJCE is fabricated via a thickness-dependent laser-induced graphitization process, in which the top cellulose layer is graphitized to form the cLIG sensing electrode, while the underlying cellulose is preserved as a rear filter for sample transport and particulate contaminants removal. The cellulose matrix further enables loading of Pt 2+ precursor to achieve one-step in-situ formation of cLIG-PtNPs with enhanced electrochemical performance. The optimized cLIG-Pt-10 electrode and glucose oxidase (GOx) functionalized GOx-cLIG-Pt-10 electrode exhibit high sensitivity for H 2 O 2 (289.03 μA mM -1 cm -2 ) and glucose (11.89 μA mM -1 cm -2 ) detection, respectively. We further applied the PJCE biosensor with the rear filter atop ex vivo pig skin coated with cosmetics for glucose detection, showing minimal signal drift of ∼2-9%, benefiting from its rear filter blocking contaminants and preventing direct skin contact. We further demonstrated an origami PJCE with a 3D fluidic design that enables vertical sample transport for glucose sensing and lateral flow to a pH sensor for multimodal detection. With low-cost materials, high conformability and facile fabrication, PJCE offers an economic and robust solution for next-generation wearable biosensors.