Scientists in Singapore have created a new hydrogel to combat the city state’s high humidity. It can also harness the moisture in the air for a range of practical applications, such as functioning as a sun or privacy screen, conductive ink and even a battery.
The gel-like material, created by a team of researchers from the National University of Singapore (NUS), was initially developed for its dehumidifying properties, aligning with Singapore’s ambitions as a leader in sustainable urban solutions. It can reduce relative humidity in a confined space from 80 per cent to 60 per cent – within the thermal comfort zone – in less than seven minutes.
The gel, a form of zinc oxide – a compound found in sunscreen – can absorb over 2.5 times its weight in water vapor and performs at least eight times better than commercial drying agents. It is suitable for both indoor and outdoor applications, meaning it could be coated on walls, windows and even used in bus stops and parks to perform a dehumidifying function. Not only is it inexpensive and easy to produce, unlike an air conditioner or dehumidifier, it requires no electricity to operate.
Assistant Professor Tan Swee Ching from the Department of Materials Science and Engineering at the NUS Faculty of Engineering, who led the research, says: “Singapore, like many tropical countries, experiences high levels of relative humidity between 70 to 80 per cent. 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.”
The research team has now received substantial funding from Temasek Foundation Ecosperity, a Singapore-based non-profit philanthropic organisation that supports the development of sustainable, innovative solutions to improve liveability, to test this novel application on a larger scale in both indoor and outdoor spaces.
Additionally, the hydrogel is being tested for other applications. Asst Prof Tan explains: “Moisture in the air is an abundant resource, but there are few attempts to harvest and put it to good use. When our novel hydrogel absorbs water, we observed that it displays interesting optical, electrical and electrochemical properties.”
As it absorbs water, the hydrogel turns from being transparent to being semi-opaque, blocking about 50 per cent of the infrared radiation in incoming sunlight. This means it could be used as a smart window material to block off the heat from natural sunlight while doubling up as a privacy screen. 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, reducing electronic waste. It’s also able to generate approximately 1.8 volts of electricity – similar to the AA battery – meaning that it could be used as a back-up power source for devices such as digital clocks.
Limited land area and natural resources, combined with a growing population, have led Singapore to take an integrated and long-term approach to sustainable urban planning and development. By 2030, the city state aims to reach even more sustainability goals that cut across energy intensity, waste management, water consumption, air quality and green environment. Given its standing as an urban solutions ‘living lab’, it has become a hub for important international urban solutions events. It hosts business events such as the World Cities Summit, CleanEnviro Summit Singapore Singapore International Energy Week, and Singapore Green Building Week to discuss and discover innovative solutions to energy, green buildings and other urban development challenges.
(via NUS, New Atlas, Visit Singapore)
Featured image: Assistant Professor Tan Swee Ching (left) and his team have invented a novel water-absorbing gel that harnesses humidity for various practical applications. (Picture credit: NUS)