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0805ctt door handle lo res

Published on August 5th, 2015 | By: April Gocha, PhD

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Power of materials: These door handles use titanium dioxide to stop the spread of germs

Published on August 5th, 2015 | By: April Gocha, PhD

[Image above] Credit: Michal Tajchert; Flickr CC BY-NC-ND 2.0

 

 

Washing your hands is one of the best things you can do to prevent the spread of disease. But no matter how many times you scrub and sanitize, there’s just some germ-ridden places that you can’t escape from touching.

 

Two new inventions, however, are using the power of materials to help prevent the spread of germs across some of the most frequently touched surfaces we encounter every day—door handles.

 

NanoTouch Materials (Forest, Va.) manufactures germ-neutralizing surfaces that can be applied directly to door handles and other oft-touched surfaces to stop germs dead in their dirty tracks.

 

The company recently scored a $2 million Tobacco Commission grant to further R&D of its germ killing products, which currently include mats, stickers, tissue box covers, and hotel channel guides. NanoTouch’s stickers, called TouchPoints, can be applied to most frequently touched surfaces, such as doors and door handles.

 

Those products incorporate the company’s innovative NanoSeptic surface, which it says is engineered with “several complex components.”

 

NanoTouch’s website says, “The materials science we deploy, molecularly bonded on a nanoscale, provides a non-leaching, self-cleaning surface using a light-powered catalytic oxidation process. Nothing is released from the surface…no toxins, heavy metals, or poisons.”

 

The one component we know is present in NanoTouch’s surfaces is titanium dioxide, whose microorganism-busting capabilities (among other uses in sunscreen, tattoo ink, and more) are well known.

 

Unlike ceramics that upconvert to kill germs, titanium dioxide is a photocatalyst—upon exposure to UV light, it generates free radicals, which are particularly deadly to microorganisms.

 

Because titanium dioxide catalyzes the reaction, it is not consumed in the process. So the surface retains its bug-busting power touch after touch. And—added bonus—it is self-cleaning.

 

Germs that land on a titanium dioxide-laden and UV-exposed surface not only die, but the energy of the reaction decomposes them all the way down to their constituent parts. No microbe carcasses are left behind to clue the crime.

 

The company says that NanoSeptic surfaces are very durable and will still work as long as the surfaces don’t show signs of wear. “While most surfaces will last 6 or even 12 months, high traffic touch points or those in critical healthcare settings might benefit from replacement every 30–90 days.”

 

NanoTouch is planning to patent its process and complete clinical trials over the next few years to demonstrate the materials’ bug-busting powers in action in health care facilities, according to a Product Design & Development article.

 

One significant problem with NanoTouch’s surfaces, however, is that the titanium dioxide requires UV activation. Indoor fluorescent lighting does emit UV light, but much lower levels than the surfaces would be exposed to outside on a sunny day. Do cloudy days provide enough UV light to activate the surface? And what about in the dark? No bug busting power then.

 

0805ctt door push lo res

New surfaces could help prevent the spread of germs on oft-touched surfaces. Credit: Kat N.L.M.; Flickr CC BY-NC 2.0

 

A couple of students have devised another possible solution to keep door handles germ-free—anytime, anywhere.

 

The two tenth-graders—Sum Ming “Simon” Wong and Kin Pong “Michael” Li, students at Church of Christ in China Tam Lee Lai Fun Memorial Secondary School (Tuen Mun, China)—designed a prototype self-activating, self-cleaning door handle.

 

The students’ design also uses the photocatalytic power of titanium dioxide, but instead of relying upon ambient UV light, they fashioned a door handle with its own incorporated LED light to initiate microbe massacre.

 

Their handle is made of clear glass coated in titanium dioxide, with the LED light affixed into one end of the handle. Opening and closing of the door generates power to turn on the light—so the system is self-powered, self-activated, and self-sanitizing.

 

According to a Science News for Students article about the invention, the team’s lab experiments showed that the handle-coating material killed ~99.8% of microbes in a lab dish.

 

But would those figures hold up on the actual LED-lit handle? LED lights do emit a small amount of UV light, although those levels are generally agreed to be much lower than fluorescent lighting. However, I couldn’t pinpoint any data about exactly how much UV light these different light sources emit, and how much UV light titanium dioxide requires for photocatalysis. [If you experts out there have any insight or data, please share in the comments below!]

 

The team presented their design earlier this year at the Intel Internatfiional Science and Engineering Fair in Pittsburgh, Pa.

 

No matter the invention, though, just remember—these surfaces kill bugs residing on the surface only, so they are no substitute for washing your hands. And next time you offer an introduction, do it with a healthy gesture of friendliness and cleanliness—fist bump, for your health.

 


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