During the past years, wearables have gained a lot of popularity in our society, from fitness trackers to health monitors. Yet, there is still an issue facing modern technology, namely what is the best way to power these devices?
First thing that usually comes to mind are batteries. Even though they are a standard solution, there is still space for improvement. They do not last long enough and sometimes people need more flexibility.
To address this, a team from Binghamton University decided to act on this issue. University Professor Seokheun “Sean” Choi, Assistant Professor Anwar Elhadad, and PhD student Yang “Lexi” Gao developed a new method to extract moisture from air and turn this water into electricity. In a recent publication in Small, the team overview their research-based device that would provide sustained powered by harvesting moisture.
“Wearable electronics will use energy-harvesting techniques in the future, but right now, the techniques are very irregular in time, random in location, and inefficiently converted. The reason why I was interested in this topic is that the moisture in our air is ubiquitous, and I realized that energy harvesting from moisture is very easy,” said Choi.
The moist-electric generator (MEG) is designed to power disposable wearable electronics by pulling moisture from the atmosphere. The novel device is constructed on a biodegradable, flexible paper base, making it an eco-friendly solution. The generator uses bacterial spores to break down water molecules into positive and negative ions. These spores can absorb water efficiently and increase their size by up to 12%.
To enhance moisture capture, the scientists integrated a Janus paper layer (with one hydrophobic and one hydrophilic side), drawing water molecules and keeping them in the device while they are being processed. This ensures that the device functions efficiently even in low-humidity environments.
The MEG creates a stable amount of electricity, enough to power small devices. For example, if 20 of these small generators are connected, they can power a small display. However, while this study is a step forward towards a new way of powering small wearable devices, there are still limitations to it. Although the MEG can work across a range of humidity levels, it is less effective in very dry conditions. Therefore, this restricts its use in certain environments.
There is also a way for improvement including increasing the power output and integrating other ways for energy generation. Choi also hopes to create a smaller design because this is “too big” for him. “I’m a MEMS guy,” he noted.
