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Printable, Transparent Force Sensing Resistive Materials for Touchscreen Applications

Dempsey, Sarah; Szablewski, Marek; Bloor, David; Atkinson, Del

Authors

Sarah Dempsey

David Bloor

Del Atkinson



Abstract

A transparent, force sensing resistive ink suitable for touchscreen technology is presented, which is capable of detecting both touch location and the applied force. The force sensing behavior is realized by a screen-printed ink layer which consists of pre-formed semi-conductive granules dispersed in an insulating polymer. The granule size is of a comparable dimension to the thickness of the printed layer. Conduction is via the creation of pressure-induced conductive pathways through the layer at the contact point. With increasing force the number of pathways increases and the resistance of the pathways decreases, reducing the resistance through the layer. The electrical behavior was tested with finger-press forces up to 5 N using a load cell and stylus attachment. Optical properties of the touchscreen were assessed using a spectrophotometer to measure the transmitted light over the range of visible wavelengths. Both the force-resistance profiles and the optical properties of the layer are dependent on the granule loading and composition. The structural, optical and force-resistance performance of test devices are discussed.

Journal Article Type Article
Acceptance Date May 25, 2015
Online Publication Date May 30, 2015
Publication Date Jan 1, 2015
Deposit Date Mar 20, 2015
Journal Key Engineering Materials
Print ISSN 1013-9826
Electronic ISSN 1662-9795
Publisher Trans Tech Publications
Peer Reviewed Peer Reviewed
Issue 644
Pages 120-124
DOI https://doi.org/10.4028/www.scientific.net/kem.644.120
Keywords Resistive touchscreen, Force sensing, Printed electronics, Functional composite ink.
Public URL https://durham-repository.worktribe.com/output/1443979