Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Smart windows that self-illuminate on rainy days

29.05.2020

Smart windows that automatically change colors depending on the intensity of sunlight are gaining attention as they can reduce energy bills by blocking off sun's visible rays during summer. But what about windows that change colors depending on the humidity outside during the monsoon season or on hot days of summer?

Recently, a Korean research team has developed the source technology for smart windows that change colors according to the amount of moisture, without needing electricity.


Metal-hydrogel-metal filter structure that repeats expansion and contraction as moisture level changes around it.

Credit: Junsuk Rho (POSTECH)

The joint research team comprised of Professor Junsuk Rho of departments of mechanical and chemical engineering, Jaehyuck Jang and Aizhan Ismukhanova of chemical engineering department at POSTECH, and Professor Inkyu Park of KAIST's department of mechanical engineering.

Together, they successfully developed a variable color filter using a metal-hydrogel-metal resonator structure using chitosan-based hydrogel, and combined it with solar cells to make a self-powering humidity sensor. These research findings were published as a cover story in the latest edition of Advanced Optical Materials, a journal specializing in nanoscience and optics.

Sensors using light are already widely used in our daily lives in measuring the ECG, air quality, or distance. The basic principle is to use light to detect changes in the surroundings and to convert them into digital signals.

Fabri-Pero interference* is one of the resonance phenomena that can be applied in optical sensors and can be materialized in the form of multilayer thin films of metal-dielectric-metal. It is known that the resonance wavelength of transmitted light can be controlled according to the thickness and refractive index of the dielectric layer.

However, the existing metal-dielectric-metal resonators had a big disadvantage in not being able to control the wavelengths of transmitted light once they are manufactured, making it difficult to use them in variable sensors.

The research team found that when the chitosan hydrogel is made into the metal-hydrogel-metal structure, the resonance wavelength of light transmitted changes in real time depending on the humidity of the environment. This is because the chitosan hydrogel repeats expansion and contraction as the humidity changes around it.

Using this mechanism, the team developed a humidity sensor that can convert light's energy into electricity by combining a solar battery with a water variable wavelength filter made of metal-hydrogel-metal structured metamterial that changes resonance wavelength depending on the external humidity.

The design principle is to overlap the filter's resonance wavelength with the wavelength where the absorption of the solar cells changes rapidly. This filter is designed to change the amount of light absorption of solar cells depending on the amount of moisture, and to lead to electric changes that ultimately detect the surrounding humidity.

Unlike the conventional optical humidity sensors, these newly developed ones work regardless of the type of light, whether it be natural, LED or indoor. Also, not only does it function without external power, but it can also predict humidity according to the filter's color.

Professor Junsuk Rho who led the research commented, "This technology is a sensing technology that can be used in places like nuclear power reactors where people and electricity cannot reach." He added, "It will create even greater synergy if combined with IoT technology such as humidity sensors that activate or smart windows that change colors according to the level of external humidity."

###

The study was supported by the Samsung Research Funding & Incubation Center for Future Technology.

Media Contact

Jinyoung Huh
jyhuh@postech.ac.kr
82-542-792-415

Jinyoung Huh | EurekAlert!
Further information:
http://postech.ac.kr/eng/smart-windows-that-self-illuminate-on-rainy-days/
http://dx.doi.org/10.1002/adom.201901932

More articles from Power and Electrical Engineering:

nachricht Anode material for safe batteries with a long cycle life
06.08.2020 | Karlsruher Institut für Technologie (KIT)

nachricht ETRI develops eco-friendly color thin-film solar cells
31.07.2020 | National Research Council of Science & Technology

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: ScanCut project completed: laser cutting enables more intricate plug connector designs

Scientists at the Fraunhofer Institute for Laser Technology ILT have come up with a striking new addition to contact stamping technologies in the ERDF research project ScanCut. In collaboration with industry partners from North Rhine-Westphalia, the Aachen-based team of researchers developed a hybrid manufacturing process for the laser cutting of thin-walled metal strips. This new process makes it possible to fabricate even the tiniest details of contact parts in an eco-friendly, high-precision and efficient manner.

Plug connectors are tiny and, at first glance, unremarkable – yet modern vehicles would be unable to function without them. Several thousand plug connectors...

Im Focus: New Strategy Against Osteoporosis

An international research team has found a new approach that may be able to reduce bone loss in osteoporosis and maintain bone health.

Osteoporosis is the most common age-related bone disease which affects hundreds of millions of individuals worldwide. It is estimated that one in three women...

Im Focus: AI & single-cell genomics

New software predicts cell fate

Traditional single-cell sequencing methods help to reveal insights about cellular differences and functions - but they do this with static snapshots only...

Im Focus: TU Graz Researchers synthesize nanoparticles tailored for special applications

“Core-shell” clusters pave the way for new efficient nanomaterials that make catalysts, magnetic and laser sensors or measuring devices for detecting electromagnetic radiation more efficient.

Whether in innovative high-tech materials, more powerful computer chips, pharmaceuticals or in the field of renewable energies, nanoparticles – smallest...

Im Focus: Tailored light inspired by nature

An international research team with Prof. Cornelia Denz from the Institute of Applied Physics at the University of Münster develop for the first time light fields using caustics that do not change during propagation. With the new method, the physicists cleverly exploit light structures that can be seen in rainbows or when light is transmitted through drinking glasses.

Modern applications as high resolution microsopy or micro- or nanoscale material processing require customized laser beams that do not change during...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“Conference on Laser Polishing – LaP 2020”: The final touches for surfaces

23.07.2020 | Event News

Conference radar for cybersecurity

21.07.2020 | Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

 
Latest News

Rare Earth Elements in Norwegian Fjords?

06.08.2020 | Earth Sciences

Anode material for safe batteries with a long cycle life

06.08.2020 | Power and Electrical Engineering

Turning carbon dioxide into liquid fuel

06.08.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>