Human-machine interfaces such as smartphone screens would be a lot cleaner and longer-lasting if we didn't have to actually touch the darn things. Scientists have now created a proximity-sensing film which makes such a scenario more possible and practical than ever before.
First of all, there already are electrically charged "noncontact sensors" which are able to detect the movements of nearby objects via their effect on magnetic and/or electrical fields. That said, these devices tend to be difficult to manufacture, they can only detect certain types of objects, plus they don't hold a charge very long.
That's where the experimental new film comes in.
Developed by scientists from the East China University of Science and Technology, it's made up of three transparent layers: fluorinated ethylene propylene (FEP) on top, an electrically conductive material in the middle, and a flexible elastomer base on the bottom. FEP is a type of material known as an electret, meaning it continuously produces an external electrostatic field after initially being charged.
The entire film is just 0.34 mm thick.
When an object of any type gets near it, that item's ingrained static charge interacts with the FEP's electrostatic field, causing an electrical current to flow in the film's conductive layer. By analyzing the strength of that current, it's possible to ascertain how far away the object is from the film.
When tested, the technology was able to detect objects made of glass, rubber, aluminum and paper, at distances ranging from to 2 to 20 mm (0.8 in). What's more, it retained its electrical charge even after more than 3,000 approach/withdraw cycles conducted over a period of nearly two hours.
In a demonstration of the film's capabilities, the scientists applied it to one lens of a pair of eyeglasses, where it detected the wearer's blinks via the approach and withdrawal of their eyelashes. Utilizing this setup, a test subject was able to blink the university's initials – E C U S T – in Morse code.
This demo suggests that once developed further, the technology could allow people who lack the power of speech to communicate, or it could warn drivers of drowsiness. And yes, it could also be utilized in interfaces such as touch-free touchscreens.
A paper on the research – which was led by Xunlin Qiu, Yiming Wang and Fuzhen Xuan – was recently published in the journal ACS Applied Materials & Interfaces.
Source: American Chemical Society
