Silver nanowire/polymer composite soft conductive film fabricated by large-area compatible coating for flexible pressure sensor array

Abstract

Soft conductive films composed of a silver nanowire (AgNW) network, a neutral-pH PEDOT:PSS over-coating layer and a polydimethylsiloxane (PDMS) elastomer substrate are fabricated by large area compatible coating processes. The neutral-pH PEDOT:PSS layer is shown to be able to significantly improve the conductivity, stretchability and air stability of the conductive films. The soft conductive films are patterned using a simple maskless patterning approach to fabricate an 8 × 8 flexible pressure sensor array. It is shown that such soft conductive films can help to improve the sensitivity and reduce the signal crosstalk over the pressure sensor array.

Recent Progress on Flexible Capacitive Pressure Sensors: From Design and Materials to Applications

“…ITO is mechanically rigid in nature and loses its mechanical properties after multiple sensing, bending, and folding operations. [ 31,33,34 ] Nanomaterials such as graphene, [ 34–36 ] nanotubes, [ 32,35 ] nanowires [ 37,38 ] are still being explored for designing highly sensitive flexible electrodes for capacitive pressure sensors, however, their basic physical properties such as surface uniformity and conductivity are limited and lack the physical properties of thin film metallic and polymeric electrodes. [ 39–43 ] Thus, these nanomaterials are usually sandwiched between two thin films when utilized as electrodes.…”

“…[ 39–43 ] Thus, these nanomaterials are usually sandwiched between two thin films when utilized as electrodes. [ 32,34–38 ] B. U. Hwang et al presented a composite electrode based flexible capacitive pressure sensor in which the top electrode is based on PEDOT:PSS/EMIM‐TCB (poly‐(3,4‐ethylene‐dioxy‐thiophene):poly‐(styrene‐sulfonate)/1‐ethyl‐3‐methyl‐imidazolium tetracyano‐borate), which is piezoresistive in nature while GIG [Au‐ITO‐AU] is chosen as bottom electrode. [ 40 ] The effect of the aspect ratio on cantilever capacitive pressure sensors is analyzed using metal coated polymer as sensing electrode.…”

Force-Sensitive Interface Engineering in Flexible Pressure Sensors: A Review

“…Therefore, the commonly used active materials include low-dimensional materials and some compressible materials, so that the active electrode materials available for flexible pressure sensors are very abundant, such as metal materials, ordinary carbon materials, some emerging two-dimensional materials, and conductive organic materials. Metal materials also include various metal nanomaterials (nano-silver [ 47 , 48 ] and nano-gold [ 38 , 49 ]), metal thin-film materials (thin-film copper [ 50 ] and thin-film magnesium [ 51 ]), metal oxides [ 13 ], liquid metals [ 52 ], etc. Ordinary carbon materials include carbon nanotubes [ 53 , 54 ], carbon black [ 55 ], bio-derived carbon materials [ 56 , 57 ], etc.…”

Transduction Mechanisms, Micro-Structuring Techniques, and Applications of Electronic Skin Pressure Sensors: A Review of Recent Advances

“…The miniaturization of these sensors must be performed with caution, since the size reduction of the sensor implies a reduction in its area, affecting its nominal capacitance and decreasing the signal-to-noise ratio or increasing the crosstalk between adjacent elements [ 30 , 43 , 72 , 74 , 75 , 76 , 78 , 79 , 80 , 81 , 82 , 83 ]. Another issue is related to the common use of polymers as dielectric layer.…”

“…Despite their low-cost, all these techniques also have a limited level of design tailoring. Fabrication of 3D printed molds [ 78 , 241 , 242 , 243 , 244 ] (majorly to micro-structure PDMS or PDMS composites) or direct printing of materials with a 3D printer [ 245 , 246 ], which is a low-cost approach to achieve a micro-structuring, nonetheless typically only allows the achievement of structures with a size in the order of few mm due to printer and filament constraints. Production of molds through laser engraving technique .…”