I wrote recently about a fascinating project from researchers at Singapore’s Nanyang Technological University that saw the creation of a new window technology that allows light in whilst keeping external noise out.

The technology is designed to be mounted onto window grills and the researchers claim it can reduce noise from outside by up to 50%. It achieves this by using ‘active noise control’ technology, which is the kind of thing commonly found in headphones to cancel out external noise.

Further advances in window technology were shown by a team of Chinese researchers, who in a recent paper highlighted technology that can control the transmittance of sunlight and heat.  Indeed, they even believe the technology can virtually eliminate E.coli from the glass, which can make it valuable for facilities such as hospitals and airplanes.

Smart windows

Traditionally, each of the various functions of a window requires unique materials.  For instance, tungsten trioxide (WO₃) is used to control visible light transmission, whereas windows that convert near-infrared solar radiation into heat is typically done via metal nanoparticles.  Being able to combine all of these into a single material has to date been a considerable challenge however.

The researchers designed an electrochromic-photothermal film composed of 3D WO₃ that was embedded with gold nanoparticles and nanorods.  The WO₃ controls the visible light that passes through the window, whilst the gold nanostructures then convert any incoming sunlight into thermal energy that will heat the interior of the building.

“This is a new strategy that achieves excellent photothermal conversion via solar gain optimization on electrochromic films and, importantly, the photothermal efficiency is adjustable during optical transmission,” the authors say.

The window was put through its paces in a demonstration that showed it was capable of changing from transparent to pitch black in a matter of minutes.  What’s more, they also showed that they were capable of increasing the temperature of the window by 24 °C in a matter of minutes.  It was equally capable of removing E. coli after it was treated with it by the research team, with the window most effective at removing the bacteria in its dark state.

The team believe that the technology will be particularly useful in aircraft and hospitals, with the multi-functionality of the technology a real selling point.  Of course, first they have to get it to market at an attractive price, and they’re a long way from that at the moment, but it’s an interesting advance from a purely technological point of view and an indication of where the tech is going.