Transparent force sensor and method of fabrication
A transparent force sensor for use in touch panel displays (touch screens) and method for fabricating the same are disclosed. The transparent force sensor is capable of detecting touch by measuring local pressure applied by a touch input to a display area of the touch screen.
1. A method of fabricating a force sensing sensor comprising:
forming a transparent polymer matrix including a plurality of transparent conducting nanoparticles, wherein forming the transparent polymer matrix comprises:
dispersing the plurality of transparent conducting nanoparticles in a first solvent system,
dispersing a transparent polymer in a second solvent system,
combining the first and second solvent systems in a predetermined ratio determined by a percolation value for the combination, and
degassing the combination;
disposing on a first surface of the transparent polymer matrix a first plurality of transparent conducting oxide (TCO) electrodes, the first plurality of TCO electrodes arranged in a first direction;
disposing on a second surface of the transparent polymer matrix opposing the first surface a second plurality of TCO electrodes, the second plurality of TCO electrodes arranged in a second direction overlaying the first direction, and
providing, by the transparent conducting nanoparticles at the cross section, a conducting path from the at least one of the first plurality of TCO electrodes to the at least one of the second plurality of electrodes, wherein, upon a force being applied at a cross section of at least one of the first and second plurality of TCO electrodes, the force can be measured by probing resistance at the cross section.
2. The method of claim 1 , further comprising;
disposing the degassed combination on a substrate to form a dry film.
3. The method of claim 2 , further comprising curing the dry film.
4. The method of claim 2 , wherein degassing the combination comprises utilizing a vacuum chamber or ambient pressure to remove a gas from the combination.
5. The method of claim 2 , wherein disposing the degassed combination on the substrate comprises spin coating, dip coating, or screen printing, or combinations thereof, the degassed combination on the substrate.
6. The method of claim 1 , wherein the first solvent system comprises at least one of methyl ethyl ketone (MEK), Toluene, Methonal, 1-Phenoxy-2-Propanol (DPPH), and another solvent with similar solvent qualities.
7. The method of claim 1 , wherein combining the first and second solvent systems comprises mixing the combination with a high speed mixer or shaker.
8. The method of claim 1 , wherein the transparent conducting nanoparticles comprise indium tin oxide (ITO), zinc oxide (ZnO), tin dioxide (SnO2), or combinations thereof.
9. The method of claim 1 , wherein the transparent polymer matrix comprises phenoxy resin, polyethers, acrylic, silicone, lacquer, or other types of transparent elastomers having similar properties, or combinations thereof.