Integrated Wearable Flexible Hydrogel Patch Sensing\nSystem for the Detection of Physiological Markers

Conventional wearable flexible sensing\nsystems typically comprise\nthree components: a flexible substrate that contacts the skin, a signal\nprocessing module, and a signal output module. These components function\nrelatively independently, resulting in a complex system that lacks\nsufficient integration. Therefore, developing an integrated wearable\nflexible sensing system by combining the flexible substrate, the signal\nprocessing module, and the signal output module not only enhances\nperformance and comfort, but also reduces manufacturing costs and\nthe risk of failure. Hydrogel substrates are particularly advantageous\ndue to their excellent biocompatibility, flexibility, and encapsulation\ncapabilities. Herein, we designed an integrated wearable flexible\nsensing system using an agarose hydrogel to encapsulate biological\noxidative enzymes (e.g., glucose oxidase (GOx), lactate oxidase, and\nethanol oxidase) and silver nanowires-polydopamine (Ag NWs-PB) as\nthe signal processing module and a color-changing TMB probe as the\nsignal output module. Additionally, we incorporated a polydimethylsiloxane-silicon\ndioxide patch to collect sweat for detecting physiological markers\n(e.g., glucose, lactate, and ethanol). An example of the application\nto facilitate visual detection of glucose in sweat was developed by\nencapsulating GOx as a biological oxidative enzyme in a sensing system.\nThe system provides results within 3.5 min and operates within a linear\nrange of 0.02 to 5.00 mmol/L, achieving a limit of detection of 0.011\nmmol/L. This innovation not only presents a more integrated and portable\nsolution for wearable hydrogel systems, but also introduces a new,\nfeasible method for detecting human physiological markers through\na straightforward detection process.