New wearable patches measure sweat during activity and rest

Researchers at the University of Tsukuba have developed an advanced wearable device that can accurately and continuously measure the amount of sweat. This innovative device is adept at monitoring sweat levels not only during physical activity, but also during rest. Its potential applications extend beyond monitoring dehydration caused by exercise or heat exposure, and include broader domains such as daily health management and disease detection.

Maintaining water balance in the body is essential for survival. While sweat is an important indicator of physical and mental health, existing wearable technologies can only monitor substantial sweat volumes.

To overcome this limitation, researchers conducted a new study and developed a lightweight (1 g), thin (1 mm thick) wearable patch that can be attached to the skin. This patch is able to accurately measure traces of insensitivity sweat, which refers to the water vapor that evaporates from the body surface even during rest. The findings are published in the diary Advanced science.

The patch’s channels, composed of sponges made of a superhydrophilic polymer, mimic the water absorption mechanisms observed in plants. This design facilitates rapid and reliable monitoring of sweat traces. In addition, sweat entering the channels is colored with a food coloring to visually confirm the volume and rate of transpiration, thus indicating the state of dehydration.

The patch also contains a sensor that continuously monitors the concentration of hydrogen ions (pH) and chemical components such as sodium, potassium and glucose ions. This allows variations in these concentrations to be detected in real time.

Experiments with applying this patch to different body parts during daily activities confirmed its effectiveness and measurement reliability. This new wearable patch offers promising applications in dehydration management, stress and tension monitoring, disease detection, sports performance optimization and more. Since the patch is worn and used individually, it is poised to make a substantial contribution to the advancement of personalized medicine.