Dual-functional ultrathin wearable 3D particle-in-cavity SF-AAO-Au SERS sensors for effective sweat glucose and lab-on-glove pesticide detection

A novel approach is developed to fabricate an ultra-thin layered flexible wearable Surface-Enhanced Raman Scattering (SERS) substrate named silk fibroin-anodic aluminum oxide-Au nanoparticles (SF-AAO-Au), which consists of biocompatible SF film as flexible support, ultrathin cavity AAO as template, and plasmonic Au NPs. The SF-AAO-Au sensor exhibits excellent SERS mechanical flexibility, homogeneity and sensitivity for its effective enhancement ability and highly ordered 3D periodic porous particle-in-cavity (PIC) arrays structure. The humidity-driven interface structure of biocompatible SF film provides good skin adhesion under various fitness tests and excellent mechanical flexibility as a wearable SERS sensor on natural skin (deformation within 5%). The flexible SF-AAO-Au can be developed as quantitative sweat glucose sensor in the concentration range of 10 − 7 ${10}^{-7}$ to 10 − 3 ${10}^{-3}$ M with a limit of detection (LOD) of 1.68 × 10 − 7 $1.68\times {10}^{-7}$ M and qualitative human sweat glucose detection ability. This SF-AAO-Au substrate can be further designed as lab-on-glove SERS sensing platform for ultrasensitive (LOD ~5.7 ppt) quantitative on-site detection of agricultural residues in a wide range. The effective dual-functional SERS wearable sensor realized for the first time paves a new way to develop smart wearable and non-destructive devices in environmental safety, forensic identification and point-of-care testing (POCT) diagnosis of physiological disease.