NUS scientists have developed a new film that they say could help convert the moisture from body sweat into energy for powering small wearable devices.
According to team leader and NUS assistant professor Tan Swee Ching, the main components of their thin film are two hygroscopic chemicals – cobalt chloride and ethanolamine. This film can rapidly release water when exposed to sunlight, and it can be ‘regenerated’ and reused for more than 100 times.
The NUS team has also designed a wearable energy harvesting device to make full use of the absorbed sweat.
It comprises of eight electrochemical cells (ECs), using the novel film as the electrolyte. Each EC can generate about 0.57 volts of electricity upon absorbing moisture.
According to the scientists, the overall energy harvested by the device is sufficient to power a light-emitting diode.
Unlike conventional hygroscopic materials such as zeolites and silica gels that have low water uptake and bulk solid structures, the new NUS film takes in 15 times more moisture and can do this up to six times faster than conventional materials.
In addition, this innovative film shows a color change upon absorbing moisture, from blue to purple, and finally pink. This feature can be used as an indicator of the degree of moisture absorption.
The NUS team has so far packaged the film into breathable and waterproof polytetrafluoroethylene (PTFE) membranes, which are flexible and commonly used in clothing.
They have also successfully demonstrated the application of the moisture-absorption film for underarm pads, shoe linings and shoe insoles.
Image and content: National University of Singapore