A "bandage" biosensor capable of collecting and analyzing sweat

　　Like other biological fluids, sweat contains a wealth of information related to substances inside the body. However, sweat collection and analysis usually rely on sweat drips or absorption from the skin surface, which is time-consuming and cumbersome. Now, researchers have developed a bandage-like biosensor that can both collect sweat and integrate it with smartphones for sweat analysis.

  　Compared to other biological fluids (such as blood), diagnostic tests for sweat are less invasive. Researchers have developed tools to collect and analyze sweat, such as temporary tattoo patches or microfluidic devices, but these devices often require wires, electronic devices, or complex structures. Tailin Xu, Li-Ping Xu, Xueji Zhang, and their colleagues hope to develop a wearable biosensor similar to a bandage, which can sample sweat and quantify various components through simple color-changing analysis.

　　To manufacture the device, researchers coated a superhydrophobic silica suspension onto a flexible polyester film. They then etch micropores into the silica layer to collect sweat. At the bottom of the hole, they place dye whose color changes depending on the pH or the concentration of chloride, glucose, or calcium. The team added adhesive underlayers and applied biosensor bandages to volunteers' skin for testing. When the subject moves, their sweat accumulates in the micropores, and the spots change color. Through mobile phone imaging and color analysis, researchers can determine that the sweat has a pH of 6.5-7.0, a chloride concentration of 100 mM, and trace amounts of calcium and glucose. Researchers are currently working to improve the sensitivity of the device.