Transparent conductive-polymer strain sensors for touch input sheets of flexible displays

Abstract

A transparent conductive polymer-based strain-sensor array, designed especially for touch input sheets of flexible displays, was developed. A transparent conductive polymer, namely poly(3, 4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), was utilized owing to its strength under repeated mechanical bending. PEDOT:PSS strain sensors with a thickness of 130 nm exhibited light transmittance of 92%, which is the same as the transmittance of ITO electrodes widely used in flat panel displays. We demonstrated that the sensor array on a flexible sheet was able to sustain mechanical bending 300 times at a bending radius of 5 mm. The strain sensor shows a gauge factor of 5.2. The touch point on a flexible sheet could be detected from histograms of the outputs of the strain sensors when the sheet was pushed with an input force of 5 N. The touch input could be detected on the flexible sheet with a curved surface (radius of curvature of 20 mm). These results show that the developed transparent conductive polymer-based strain-sensor array is applicable to touch input sheets of mechanically bendable displays.

Mutual Capacitive Flexible Tactile Sensor for 3-D Image Control

“…Similar to those in previous studies [34], capacitance changes were larger at smaller bending radii, which implies that the reduced air gap between the two electrodes contributes to higher sensitivity. However, in contrast with the simulation results showing that the air gap decreased with bending, which increases capacitor sensitivity, the measurement results show reduced sensitivity with decreased bending radii in Fig.…”

“…Many studies have claimed that their functional materials were fabricated on flexible substrates with simple picture demonstration of their flexibility with unspecified radius (r) or cyclic reliability for specific materials and not the whole sensor structure [33], [37]- [42]. Other reports have mentioned material resistance change or the characteristic changes in tactile sensors when bent [34], [43] but excluded analysis on how the sensor behaves when bent. No research discusses the sensitivity of tactile sensors influenced by mechanical force.…”

Aerosol-Printed Strain Sensor Using PEDOT:PSS

“…Among the strain sensitive materials, PEDOT:PSS has received attention as a good candidate for producing low cost printed strain sensors due to the material's inherent piezoresistive characteristics. For example, solution-processed PEDOT:PSS has been used to create strain sensors by inkjet printing on textiles [15], paper [16], and plastics [16], [17]. Although PEDOT:PSS exhibits piezoresistive characteristics, the material also has several drawbacks caused by environmental dependency.…”

Novel MEMS Devices Based on Conductive Polymers

“…12 Light transmissive display elements were also constructed based on the electrochromic function, which involves color changes from reversible electrochemical reactions. 13 Memory elements were also constructed based on reversible electrochemical reactions.…”