Humidity-hungry hydrogel could be the next cool thing

Many people will tell you, "It's not the heat, it's the humidity." It was with this in mind that scientists at the National University of Singapore recently created a hydrogel that draws moisture from the air, making the Southeast Asian heat more tolerable … but the material also has a few other tricks up its sleeve.

"Singapore, like many tropical countries, experiences high levels of relative humidity between 70 to 80 per cent," says Assistant Professor Tan Swee Ching, who led the research. "In a humid environment, the air is saturated with water and as a result, sweat on our body evaporates more slowly. This causes us to feel hotter than the actual ambient temperature, leading to great discomfort. Our novel hydrogel aims to achieve a cooling effect by removing moisture from ambient air very efficiently."

That gel is largely made up of zinc oxide, which can absorb over 2.5 times its weight in water vapor. Not only is it inexpensive and easy to produce, but it also reportedly performs eight times better than other drying agents such as silica gel and calcium chloride. And unlike an air conditioner or dehumidifier, it requires no electricity to operate.

"It can be easily coated onto walls, windows and even decorative items (such as a sculpture) to perform the dehumidifying function," says Tan.

If applied to windows, the hydrogel could also help to actually bring down the temperature in a room. This is because as it absorbs water, it turns from being transparent to being semi-opaque, blocking about 50 percent of the infrared radiation in incoming sunlight. As a result, it is claimed to be capable of reducing a room's ambient temperature by over seven degrees Celsius. Applying an electrical current to the material returns it to its transparent state.

Additionally, because the hydrogel is bendable and electrically conductive, it could be used as a conductive ink on circuit boards in flexible electronic devices – when it came time to recycle those boards, the gel could be easily removed using a solvent such as vinegar. It's also able to generate approximately 1.8 volts of electricity, meaning that it could be used as a back-up power source for devices such as digital clocks.

A paper on the research was recently published in the journal Energy & Environmental Science. The gel can be seen in use, in the video below.

Source: National University of Singapore