Versatile sweat bioanalysis on demand with hydrogel-programmed wearables

Wearable sweat bioanalysis is promising for non-invasive diagnostics of diseases. However, collection of representative sweat samples without disturbing daily life and wearable bioanalysis of targets that are clinically significant are still challenging. In this work, we report on a versatile method for the sweat bioanalysis. The method is based on a thermoresponsive hydrogel which can imperceptibly absorb slowly secreted sweat without stimulation such as heat or sport exercise. The wearable bioanalysis is accomplished by programmed electric heating of hydrogel modules to 42°C to release absorbed sweat or preloaded reagents into a microfluidic detection channel. Using our method, not only one-step detection of glucose but also multi-step immunoassay of cortisol is accomplished within 1 h, even at a very low sweat rate. Our test results are also compared with those obtained with conventional blood samples and stimulated sweat samples to evaluate the applicability of our method to non-invasive clinical practice.