All-polymer variable resistors as pressure-responsive devices photochemically assembled using porous composites and flexible electrodes based on conducting polymers

Abstract

In this study, we fabricated and characterized all-polymer pressure sensors integrated with transduction modules based on conducting polymers. The architecture of the all-polymer pressure sensor is based on a porous conductive blend sandwiched between two flexible conductive polymeric electrodes. When an external pressure is applied to the pressure sensor, the porous conductive blend can act like a variable resistor to indicate the magnitude of the external pressure in terms of a corresponding electrical resistance reading. Different types of conducting polymers were used in two different modular components for fabricating our pressure sensors. The flexible all-polymer electrodes were prepared by coating poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) on poly(ethyleneterephthalate) substrates. The sheet resistance of our flexible conducting polymeric electrodes was measured to be ∼400 Ω/Square. The porous variable resistor component was made by photopolymerization of a UV-curable glue mixed in a powder of polystyrene and polyaniline doped with camphorsulfonic acid. The dimensions of the fabricated transduction modules were ∼2 cm × ∼2 cm and ∼600 µm in thickness. A preliminary study on the electrical response of our prototype pressure sensors to pressure stimuli was carried out. The result showed that, upon application of pressure stimuli, the transduced electrical resistance could be changed from 122 to 52 kΩ when the pressure was varied from 0 to 145.2 kN/m2.