Fabrication of a flexible and transparent touch sensor using single-walled carbon nanotube thin-films

Reported herein are the fabrication and demonstration of a flexible and transparent touch sensor using carbon nanotube thin films (CNTFs). The CNTF was fabricated by vacuum filtration and was transferred CNTF to polydimethylsiloxane (PDMS) by water-assisted stamping method. The sheet resistance of the CNTF decreased by approximately 74% after HNO3 treatment. The CNTF touch sensor was fabricated similarly to the conventional four-wire touch screen structures. PDMS was used for the upper plate to absorb the tensile and compressive strain and polyethylene terephthalate (PET) for the lower plate to provide device stability during bending action. The CNTF touch sensor showed high optical transmittance (over 80%) and high sensitivity with the measured touch activation pressure of 23 kPa. Cyclic pressure (38 kPa) was applied at 0.5 Hz and good repeatability was found for several hundred cycles. The results show that the CNTF flexible touch sensor can be applied to future flexible electronic interfaces such as, e-paper and flexible displays.