“Higher output than a conventional AA battery.” Those words grabbed Health Tech Insider publisher Alfred Poor’s attention. We’ve covered a variety of new battery technologies including 3D printed batteries, sweat-powered batteries, and stretchable batteries. A team from the National University of Singapore’s (NUS) College of Design and Engineering (CDE) recently published a report in Advanced Materials describing how the moisture-driven energy generation (MEG) technology has the potential to power consumer electronic devices simply from the air, including wearables.
The NUS engineers focused on maintaining different water content in two regions of a thin layer of commercially available fabric. The fabric is made from wood pulp and polyester. The team coated the entire fabric with carbon nanoparticles. The team coated the wet, hygroscopic region of the fabric with a sea salt ionic hydrogel. The gel can harvest more than six times its weight in moisture from ambient air. The dry region of the fabric does not have the hydrogel coating over the carbon nanoparticle coating. Positively charged Ions from sea salt free up when the wet region absorbs water in the air. The carbon nanoparticle layer is negatively charged. The MEG generates an electrical field when the carbon nanoparticles absorb the free positive ions. The best trick in the NUS design is maintaining a significant difference in moisture content between the wet and dry regions. According to the development team, testing showed the technology can continue to output electrical energy after exposure for 30 days in a humid environment.
The NUS battery technology is highly flexible and scalable in addition to its composition of low-cost, sustainable materials. According to an NUS news release, the team demonstrated the technology’s flexibility “by folding the battery fabric into an origami crane which did not affect the overall electrical performance of the device.” The team also installed three connected pieces of the battery fabric in a 3D printed case of a conventional 1.5 volt AA battery. The same size battery with the NUS tech generated as much as 1.96 volts. In other tests, the self-charging, wet-dry fabric battery continued to generate electricity for up to 150 hours.
Next steps for the NUS engineers include filing for a patent for their technology and exploring opportunities for commercial applications. We look forward to hearing much more about ambient moisture-driven battery tech for small electronic devices.