Yorkshire-based materials firm Peratech has developed a transparent version of QTC, its touch-sensitive elastomer.
Called 'QTC Clear', the firm is aiming it at touch screens.
QTC - Quantum Tunnelling Composite - is a pressure sensitive resistive material that can be designed to give several decades of resistivity decrease with increasing pressure.
For a touch screen, a layer 6-8µm thick is sandwiched between two layers of indium-tin oxide (ITO) coated glass or hard plastic. Deflections of 1-2µm can be detected.
“Both resistive and capacitive touch screen technologies have their drawbacks,” said Peratech CEO Philip Taysom. “Resistive is not very accurate and can’t do multi-touch well so it is becoming less popular than capacitive, but the latter uses a lot of power constraining it to smaller screen sizes. QTC Clear can be made in any size and provides multi-touch, sensitivity, accuracy, low power consumption and adds the third dimension of pressure."
Multi-touch capability is achieved by replacing the upper and lower ITO conductor sheets with an X-Y grid.
According to the firm, resistive touch screen manufacturers can change to QTC while retaining their existing manufacturing procedures and equipment, because the technology is essentially resistive - replacing the usual 20µm gap and spacer dots with the thin QTC layer.
Taysom admits that the material with its attendant glass and ITO is not completely clear, imparting some attenuation and hazing.
The optical performance decrease due to a single layer of the new material is less than that of a single ITO layer, he said: "a QTC touch screen would be significantly better optically than a resistive touch screen".
Comparing it with existing technology, where capacitive touch is more expensive and better optically that conventional resistive touch, Taysom said: "QTC Clear is between the optical performance of capacitive and resistive touch screens, and between the cost of capacitative and resistive touch screens."
Quantative optical and price data will be released in Q3 when mass production begins.
Actuation force of a typical glass-fronted QTC touch screen would be "10g comfortably and 5g can be achieved, and up to 1kg", said Taysom.
By exploiting the materials predictable force-resistance curve, force can be added as a third dimension of screen touch, which is why Peratech is also marketing QTC at capacitive touch screen makers.
"Capacitive touch screen manufacturers can augment with the addition of QTC Clear to provide additional features from the force sensitivity such as touch activation of the capacitive matrix to save power, 3D menus, variable line widths, and more intuitive gaming interaction," said the firm. "Very little alteration is needed to the control electronics in either case except to take advantage of the new features."
Firms including Samsung and Nissa have licensed Peratech's opaque QTC material and are manufacturing products, and there is already one undisclosed licensee for the transparent version.
QTCs are made from metallic or non-metallic filler particles combined in an elastomeric binder.