Tag Archives: paint

The porous polymer coating reflects sunlight and emits heat to passively cool off buildings. Credit: Jyotirmoy Mandal/Columbia Engineering.

Polymer paint passively cools down any surface

The porous polymer coating reflects sunlight and emits heat to passively cool off buildings. Credit: Jyotirmoy Mandal/Columbia Engineering.

The porous polymer coating reflects sunlight and emits heat to passively cool off buildings. Credit: Jyotirmoy Mandal/Columbia Engineering.

Heat-waves are on the rise all over the world, becoming more frequent and more intense. Developing countries are the hardest hit: not only are heat waves more extreme than in other parts of the world but cooling methods are also more difficult to implement due to cost. In such situations, passive cooling — which doesn’t require electricity or any kind of energy input — is the way to go.

Plastics and other cheap polymers are actually excellent heat radiators, which would make them ideal for passive daytime radiative cooling (PDRC) if scientists could figure out how to get these normally transparent surfaces to reflect sunlight without using silver mirrors.

Researchers at Columbia University have finally been able to accomplish this. Reporting in the journal Science, the authors described a PDRC polymer coating with nano- and micro-scale voids that act as passive air coolers. The amazing part is that the coating can be applied like paint on rooftops, buildings, vehicles — basically anything.

Apply and cool

A passive cooling surface is effective when it has a high solar reflectance and emittance. In other words, if these two variables are high enough, there’s a net heat loss effect ever under intense sunlight.

The cheapest and, often times, most practical PDRC is white paint. If you’ve ever switched a black shirt for a white shirt on a hot summer day, you must know how much of a difference this can make.

The problem with white paint, however, is that it doesn’t reflect longer wavelengths of light, so its cooling performance is modest.

Passive daytime radiative cooling (PDRC) works by reflecting sunlight and emitting heat in order to achieve a net heat loss. This way, a surface can attain sub-ambient temperatures. Credit: Jyotirmoy Mandal.

Passive daytime radiative cooling (PDRC) works by reflecting sunlight and emitting heat in order to achieve a net heat loss. This way, a surface can attain sub-ambient temperatures. Credit: Jyotirmoy Mandal.

Using phase-inversion, the Columbia Engineering team was able to introduce light-scattering air-voids in polymers. The process involved mixing the polymer with a solvent alongside water, in which the polymer is insoluble. Ultimately, the pigments in white paint were replaced with air voids that reflect all wavelengths of light, from UV to infrared. And even though there were no pigments, the polymer still turned white.

What you get is a far better performance than typical white paint and even better than some state-of-the-art PDRCs that are complex and costly. What’s more, there’s the convenience that the polymer coating can be applied like paint to virtually any surface.

During tests, the coating kept surfaces significantly cooler than the surrounding environment under widely different skies. For instance, the polymer paint cooled surfaces by 6°C in the warm, arid desert in Arizona and 3°C in the foggy, tropical environment of Bangladesh.

Another selling point is stability. For instance, cellulose, which is the main component of paper, turns yellow over time. The porous films developed at Columbia, however, did not seem to change one bit over the course of a month in the field.

“The fact that cooling is achieved in both desert and tropical climates, without any thermal protection or shielding, demonstrates the utility of our design wherever cooling is required,” Yuan Yang, assistant professor of materials science and engineering, said in a statement.

“Now is a critical time to develop promising solutions for sustainable humanity,” Yang added, “This year, we witnessed heat waves and record-breaking temperatures in North America, Europe, Asia, and Australia. It is essential that we find solutions to this climate challenge, and we are very excited to be working on this new technology that addresses it.”

Until not too long ago, white was thought to be the most challenging color to manufacture. The new research, however, shows that, in fact, white can be the most attainable color.

“It can be made using nothing more than properly sized air voids embedded in a transparent medium. Air voids are what make snow white and Saharan silver ants silvery,” Nanfang Yu, associate professor of applied physics said in a statement.

Titanium dioxide nanoparticles.

White paint might be causing a lot of Type 2 diabetes, preliminary research finds

A pilot study from The University of Texas at Austin suggests white paint and Type 2 diabetes might be linked.

Titanium dioxide nanoparticles.

Titanium dioxide nanoparticles.
Image credits University of Turin.

In the mid-20th century, titanium dioxide (TiO2) overthrew lead-based compounds (which were really toxic) as the go-to white pigment. Today, it’s the most widely used white pigment, mixed into everything from food and medication to plastic and paper. We rely on this substance a lot, as we’re producing in excess of 9 million metric tons of the stuff per year.

However, the pigment may not be as harmless as we’ve believed. Preliminary research has found TiO2 crystals embedded in pancreas tissue afflicted with Type 2 diabetes (T2D).

The white tint of diabetes

The team worked with 11 pancreas specimens, 8 from donors with T2D and 3 from donors who didn’t have the condition. The specimens were provided by the Juvenile Diabetes Research Foundation nPOD at the University of Florida at Gainesville.

The last three samples didn’t contain any detectable levels of TiO2 crystals. The 8 specimens with T2D, however, all had TiO2 crystals embedded in their tissues. The researchers report finding over 200 million TiO2 crystallites per gram of TiO2 particles in the specimens of donors with diabetes.

It’s particularly suspicious to find TiO2 crystals in all of the T2D specimens since titanium dioxide doesn’t have any known role in human biology. Furthermore, while plenty of different salts and other metallic compounds have a role to play in our bodies, there is no known role for titanium salt or another type of titanium compound in our biochemistry.

“Our initial findings raise the possibility that Type 2 diabetes could be a chronic crystal-associated inflammatory disease of the pancreas, similar to chronic crystal-caused inflammatory diseases of the lung such as silicosis and asbestosis,” said Adam Heller, the study’s lead author.

Heller is a professor in the McKetta Department of Chemical Engineering in the Cockrell School of Engineering. He has had a life-long career of diabetes research, for which he received the National Medal of Technology and Innovation in 2007.

Statistics from the World Health Organization show that the number of diabetes patients has quadrupled over the past four decades, reaching some 425 million known cases today. T2D represents the majority of these cases.

Although rising obesity rates and higher average life expectancy (which means more people reach old age) are considered the main factors driving this increase in T2D, the team isn’t convinced. Heller suggests that the increased use of titanium dioxide during these past few decades may be a key, if overlooked, driver of the condition.

“The increased use of titanium dioxide over the last five decades could be a factor in the Type 2 diabetes epidemic,” he said.

“The dominant T2D-associated pancreatic particles consist of TiO2 crystals, which are used as a colorant in foods, medications and indoor wall paint, and they are transported to the pancreas in the bloodstream. The study raises the possibility that humanity’s increasing use of TiO2 pigment accounts for part of the global increase in the incidence of T2D.”

The findings, right now, are far from convincing — but they are, potentially, very far-reaching. This was only a pilot study, with a very limited sample; Heller will repeat the study using a larger sample.

The paper “Association of Type 2 Diabetes with Submicron Titanium Dioxide Crystals in the Pancreas” has been published in the journal Chemical Research in Toxicology.

Electrick brain.

Spray-on touchscreen can turn almost anything into a sensor with a flick of the wrist

Carnegie Mellon University researchers have managed to fit the ever-so-convenient touchpad in a spray can. Using this technology, any surface, regardless of size or shape, can be turned into a working touchpad.

Electrick brain.

The researchers can turn a range of surfaces — even this brain-shaped Jell-O mold — into touchpads.
Image credits CMU.

We’re used to seeing touch sensitivity employed on flat, often small surfaces, such as tablets or smartphones. This mostly comes down to the cost associated with building the devices, and the need to install them on mechanically-resilient frames. But imagine you could take any finished object and then cheaply coat it in a touch-sensitive layer as easily as spraying some paint on it.

You can with this can

That’s what researchers at CMU have been working on. Dubbed Electrick, their spray can turn everything from walls to Jell-O into touch-sensitive sensors. The coating functions much like other touchscreens, through the shunting technology — when you touch the screen, the layers connect and a small charge is shunted to the electrodes. Several electrodes on the edge of the sensor/coating pick up these signals. By first applying electrically conductive paint-like layers onto objects and then connecting a series of electrodes to them, the researchers showed that they can pinpoint the exact point of touch on the surface using a technique called electric field tomography.

Electrick could solve some of the current limitations of touch-sensitive technology. For instance, large touch surfaces are expensive to produce, and flexible ones are still confined to research and development labs as of now. But the spray-on touch sensor can be applied “on almost anything” says Chris Harrison, assistant professor in the Human-Computer Interaction Institute (HCII), head of the Future Interfaces Group, and first author of the paper, taking on the shape as well as the flexibility of the base objects. The technology should be both accessible to hobbyists and compatible with common manufacturing methods, such as spray coating, vacuum forming, casting/molding, or 3D printing, the team reports.

The technology does have some limitations. In comparison to traditional touch devices, Electrick isn’t as accurate. But with a one-centimeter margin or error, it’s more than precise enough to comfortably allow the use of buttons, sliders, or other controls.

The team used the coating to cover objects including a 4-by-8 ft (1.2 x 2.4 meters) sheet of drywall, a steering wheel, a guitar, a Jello-O mold of the human brain, even some Play-Doh. They also used the coating to make an interactive smartphone case, which could, for example, open the camera app when held a certain way, and a game controller which could change the location of its buttons and sliders based on the game or user preference.

 

Overall, the team reports that the coating proved to be durable during their testing, but will not look into adding a protective coating atop the conductive layers to make the screens more wear-proof.

The findings will be presented at CHI 2017, the Conference on Human Factors in Computing Systems, in Denver later this week.

crystal_audio

Science turns psychedelic: an amazing TED talk

crystal_audio

A while ago, ZME Science featured the brilliant work of  Fabian Oefner, a Swiss artist and photographer, who mixes various artsy techniques (paints, photography, glasswork etc) with science.

crystal_audio1

Thus, he came up with some truly fantastic pieces of art from mixing paint with magnetic liquid, to using colored crystals that pattern under sound waves (pictured in the GIFs), to setting whiskey on fire. For your daily dose of awe, check out Oefner’s TED talk embedded in this article.

(LEFT) Conventional lithium-ion batteries wrap active layers into a canister or other portable container. (x3 RIGHT) Rice University researchers have found a way to paint those layers onto any surface, which opens up the possibility of turning those surfaces into storage devices. (credit: Neelam Singh/Rice University)

Scientists develop paint that can turn any surface into a battery

In today’s fast evolving world of tech, miniaturization is crucial. In most portable consumer electronics goods, like smartphones or tablets, the typical lithium-ion battery takes up quite its share of space, impending further sensible miniaturization of design. A new technique developed by scientists at Rice University might, however, render battery volume to a minimum, following the advent of a special paint, which when applied on a surface turns it into a battery.

(LEFT) Conventional lithium-ion batteries wrap active layers into a canister or other portable container. (x3 RIGHT) Rice University researchers have found a way to paint those layers onto any surface, which opens up the possibility of turning those surfaces into storage devices. (credit: Neelam Singh/Rice University)

(LEFT) Conventional lithium-ion batteries wrap active layers into a canister or other portable container. (x3 RIGHT) Rice University researchers have found a way to paint those layers onto any surface, which opens up the possibility of turning those surfaces into storage devices. (credit: Neelam Singh/Rice University)

The rechargeable  lithium ion battery paint is applied in layers, mimicking conventional battery construction comprised of five layers –  a positive and a negative current collector, a cathode, an anode and an ion-conducting separator in the middle. However, each layer is sprayed or painted on rather than pieced together, thus eliminating design restrictions.

“Paintable batteries have the capability of direct and seamless integration with objects,” Neelam Singh, lead author on the study.

Such a technique could be used to add batteries to new technologies such as solar panels, or even turn your T-shirt into a moving battery that could power tiny gadgets.

How does the spray-on battery work in practice


The researchers tested the adherence of the materials on different substrates by airbrushing them onto stainless steel, glass, flexible polymers, bathroom tiles and even on a beer stein. Scientists tested nine bathroom tile-based batteries in parallel, of which one was mounted with a solar cell, which generates power from a white lab light. When the batteries were completely charged by the house current and solar panel, they were able to power an array of LEDs that illuminated the word ‘RICE’ for 6 h. Moreover, the batteries delivered a constant 2.4 V.

[RELATED] Solar paint promises to turn any surface into a solar cell

The resulting batteries have poor life, though, of only 60 cycles and the outputted power, as you can see, is rather modest. Moreover, the scientists have to cater to some worrisome safety measures, like making the electrolyte separator layer  oxygen stable; currently there’s the possibility of an explosion if it came into contact with air.

“We have demonstrated the concept of paintable batteries, and the next step is to develop new materials for the battery that are not air- or moisture-sensitive, [and are] non-toxic and safe to handle by non-experts,” said Singh. “We are also working on developing paints for packaging the battery and making every layer, including packaging, by spray-painting technique.”

The technique, however, is still in its incipient phase, and while it may be many years away from becoming a viable, commercially available option, it demonstrates that it has the potential to revolutionize the current portable and energy-storage industry.

“Our current work is the demonstration of the paintable battery concept, but it opens up immense possibilities of integration with energy capture devices such as solar cells, as well as objects of daily use,” she said. “We think that it can be used with printed electronics, RFID or other smart objects.”

Findings were reported in the journal Scientific Reports.

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