Touch sensors have replaced keys and controls in many devices and gadgets. In combination with displays very intuitive control possibilities have been created. The most common principles to sense touch are resistive systems and projected-capacitive systems (mutual-capacitance and self-capacitance). These approaches are all based on electrical conductivity of transparent layers. In this paper a new method to attain very thin and flexible touch sensors manufactured by a high resolution roll-to-roll production process on plastic substrate is presented. The conductivity is based on a metallic grid, occupying only a small fraction of the surface and due to structure sizes down to 10μm appearing transparent. Using two layers of such a transparent conductive film (PolyTC) we can process touch sensors in a resistive or in the projected-capacitive setups, being capable of multi-touch sensing. These touch sensors are compatible with conventional image processing controllers. They are flexible and have a total thickness of less than 200μm.
Dietmar Zipperer, "Touch Sensors based on PolyTC Transparent Conductive Films" in Proc. IS&T Int'l Conf. on Digital Printing Technologies and Digital Fabrication (NIP28), 2012, pp 549 - 549, https://doi.org/10.2352/ISSN.2169-4451.2012.28.1.art00073_2