With such a small gap, the materials used to sandwich the polymer don’t need to be as soft. Glass, which is much harder than the softer materials found in resistive screens, could make the screens more durable. Additionally, says Taysom, less light is lost with the clear polymer than with an air gap, which translates into less power required to light up the screen.
Peratech isn’t the only company developing force-sensitive materials. For years, musical instruments, such as electric pianos, have used a force-sensitive resistor ink, in which microscopic particles conduct electricity in response to varying pressure. In 2009, a startup out of New York University called Touchco that employed transparent force-sensitive resistor ink for touch screens was acquired by Amazon, although no products using the technology have been announced.
Peratech has already licensed earlier, opaque versions of its QTC material. These versions can be found in toys, medical devices, and backpacks with built-in MP3 controls. QTC Clear marks the company’s entry into the display industry.
The technology differs from traditional pressure-sensitive inks, says Taysom, because of the electrical properties of the conductive polymers within the composite. Conductive particles in traditional inks are spherical and come in contact with each other when pressure is applied—as more particles come in contact, the material becomes more conductive. QTC’s conductive particles, in contrast, are spiky and held together in silicon rubber, which is electrically insulating. Electrons at the tip of the spikes transfer to the tips of other spikes , conducting electricity over a small distance without touching in a process called quantum tunneling. As a result, the composite responds to even very light pressure, says Taysom.
“Pressure-sensitive space is an important place to be,” says Daniel Wigdor, professor of computer science at the University of Toronto. “It adds a third dimension so you can push into the screen and better manipulate things.” Wigdor says the low power capabilities of QTC Clear could benefit smaller screens such as those on tablets.
But QTC Clear requires some pressure to be applied in order to respond. “The best user experience today is offered by capacitive screens,” says Patrick Baudisch, professor of computer science at the Hasso Plattner Institute in Potsdam, Germany. “This sounds like a minor detail, but in reality in matters a lot because it allows users to flick to scroll or pan through documents or Web pages.”
Consumers will soon have a chance to feel for themselves. According to Taysom, Peratech has licensed QTC Clear to manufacturers. He expects the first product to be available by the end of the year.