Sweating is not exactly pleasant, but it is a normal and natural way for the human body to regulate body temperature by decreasing heat stress, which can occur for a number of reasons including exercise, temperatures high, consuming spicy foods or when you are experiencing anxiety or embarrassment. Researchers from the National University of Singapore (Naked) has created a new film that can evaporate sweat six times faster and use harvested moisture to power portable electronic devices. They recently published an article about their work, titled “Super-hygroscopic film for portable devices with two functions of accelerating sweat evaporation and energy recovery,»In the scientific journal Nano energy, and 3D printed a prototype product for what appears to be a very useful application.
The abstract states: “Despite the development of techniques for collecting water from the atmosphere, few attempts have been made with a broader horizon – absorbing moisture from evaporation of sweat, which has substantial implications for human comfort and portable electronics. Here, a super-hygroscopic cobalt complex (Co-SHM) material is developed to accelerate sweat evaporation and fabricate moisture-triggered energy harvesting devices. Co-SHM exhibits transparent thin film structure, fast absorption kinetics and high water absorption of 4.6 gg-1. The regeneration of the material can be driven by natural sunlight, making Co-SHM an energy efficient moisture absorber. By integrating Co-SHM into breathable and waterproof PTFE membranes, we design new types of armpit pads, shoe linings and insoles, which can quickly absorb moisture from sweat to prevent build-up of sweat, thus providing a dry and comfortable microclimate for people. In addition, absorbed sweat can be turned into energy through portable energy harvesting devices based on Co-SHM.
The authors of the research paper are Xueping Zhang, Jiachen Yang, Ramadan Borayek, Hao Qu, Dilip Krishna Nandakumar, Qian Zhang, June Ding, Swee Ching Tan, all from the university’s materials science and engineering department.
“Sweat is mainly made up of water. When water evaporates from the skin’s surface, it lowers the skin temperature and we feel cooler, ”said research team leader Assistant Professor Tan Swee Ching. “In our new invention, we have created a new film that is extremely effective in evaporating the sweat from our skin and then absorbing the moisture from the sweat. We’re also going a step further by converting the moisture from sweat into energy that could be used to power small, portable devices.
The new film is made from cobalt chloride and ethanolamine, hygroscopic (moisture-absorbing) chemicals. Most hygroscopic materials, like silica gels or zeolites, exhibit loose solid structures and low water absorption, which means they are not ideal for absorbing moisture from the evaporation of the gas. sweat. But Team NUS’s film could absorb 15 times more moisture than these other hygroscopic materials, and when exposed to sunlight, it can release water very quickly. Plus, the film changes color from blue to purple and then pink when it absorbs moisture, which is a pretty nifty way to tell how much moisture has been absorbed. Finally, the film can actually be regenerated when placed in the sun and reused over 100 times, which is great news in terms of durability.
In a proof-of-concept demonstration, the researchers designed a portable device that uses film as an electrolyte and recovers enough energy from the moisture it absorbs to power a light-emitting diode, without using batteries. Each of the eight electrochemical (EC) cells that make up the device can generate approximately 0.57 volts of electricity.
The team also demonstrated how their new moisture-wicking film can be used to solve some of the common problems associated with heavy sweating. They packaged their new film in waterproof and breathable polytetrafluoroethylene (PTFE) membranes, which are often used in clothing due to their flexibility. Then these membranes were used as a prototype underarm cushion, as well as a prototype lining and insole for a shoe.
“The prototype of the shoe’s insole was created using 3D printing,” said research team co-leader Professor Ding Jun. “The material used is a blend of soft polymer and hard polymer, providing sufficient support and shock absorption.
“Underarm sweating is embarrassing and frustrating, and this condition contributes to the growth of bacteria and leads to unpleasant body odor,” Assistant Professor Tan said. “The build-up of sweat in shoes could lead to health problems such as blisters, calluses and fungal infections. Using the underarm pad, shoe lining and shoe insole encrusted with the moisture-absorbing film, moisture from evaporating sweat is quickly absorbed, preventing sweat build-up and providing a dry and cool microclimate for personal comfort.
The next step for the researchers at NUS and their new moisture-absorbing film is to work with companies that could allow them to add the film into consumer products.
(Source: Phys.org / Images: National University of Singapore)