Development of a carbon nanotube-based touchscreen capable of multi-touch and multi-force sensing

Wonhyo Kim, Haekwan Oh, Yeonhwa Kwak, Kwangbum Park, Byeong Kwon Ju, Kunnyun Kim

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

A force sensing touchscreen, which detects touch point and touch force simultaneously by sensing a change in electric capacitance, was designed and fabricated. It was made with single-walled carbon nanotubes (SWCNTs) which have better mechanical and chemical characteristics than the indium-tin-oxide transparent electrodes used in most contemporary touchscreen devices. The SWCNTs, with a transmittance of about 85% and electric conductivity of 400 Ω per square; were coated and patterned on glass and polyethyleneterephthalate (PET) film substrates. The constructed force sensing touchscreen has a total size and thickness of 62 mm × 100 mm × 1.4 mm, and is composed of 11 driving line and 19 receiving line channels. The gap between the channels was designed to be 20 μm, taking visibility into consideration, and patterned by a photolithography and plasma etching processes. The mutual capacitance formed by the upper and lower transparent electrodes was initially about 2.8 pF and, on applying a 500 gf force with a 3 mm diameter tip, it showed a 25% capacitance variation. Furthermore, the touchscreen can detect multiple touches and forces simultaneously and is unaffected by touch material characteristics, such as conductance or non-conductance.

Original languageEnglish
Pages (from-to)28732-28741
Number of pages10
JournalSensors (Switzerland)
Volume15
Issue number11
DOIs
Publication statusPublished - 2015 Nov 13

Keywords

  • Multi-force
  • Multi-touch
  • Single-walled carbon nanotubes (SWCNTs)
  • Touchscreen

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Atomic and Molecular Physics, and Optics
  • Instrumentation
  • Electrical and Electronic Engineering

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