Longzhi Yuan
Non-invasive, real-time, and continuous monitoring of human health play an important role in tackling current issues in the society such as chronic diseases, suboptimal health, and an aging population. Diabetics, for instance, frequently need to check their glucose levels to modify their treatment plans. Traditional blood testing compromises the skin barrier, causing discomfort and introducing infection risks. Portable glucose meters, although convenient, also require a breach of skin integrity, posing similar drawbacks. We found the analysis of sweat components as a relatively superior alternative. It has been shown that the concentration of organic substances such as glucose and lactic acid, as well as inorganic salt ions such as hydrogen and chlorine in sweat is closely related to common chronic diseases such as diabetes, localized anemia, and cystic fibrosis disease. On the other hand, sweat is easily accessible on the skin's surface, obviating the need for invasive collection methods. Cutting-edge electrochemical studies reveal that sensors for various sweat constituents can be amalgamated onto a diminutive, pliable substrate, facilitating easy deployment and usage. Nonetheless, requisite signal processing and data collection for these sensors are often hamstrung by their bulkiness and limited operational range. To address these issues, we have fused electrochemical sensing with backscatter communication to design a wearable bracelet capable of detecting concentrations of glucose, lactate, potassium, sodium, hydrogen, and chlorine in sweat. This data can be wirelessly transmitted to a smartphone, where it undergoes calibration to yield results with less than 5% discrepancy. Moreover, we have outfitted the bracelet with an energy-harvesting module that harnesses power from environmental light, radio frequencies, and the body's thermal energy, ensuring the device's sustained functionality.
Fig：the structure