Microporous Polypyrrole‐Coated Graphene Foam for High‐Performance Multifunctional Sensors and Flexible Supercapacitors

Abstract

This study reports on the fabrication of pressure/temperature/strain sensors and all‐solid‐state flexible supercapacitors using only polydimethylsiloxane coated microporous polypyrrole/graphene foam composite (PDMS/PPy/GF) as a common material. A dual‐mode sensor is designed with PDMS/PPy/GF, which measures pressure and temperature with the changes of current and voltage, respectively, without interference to each other. The fabricated dual‐mode sensor shows high sensitivity, fast response/recovery, and high durability during 10 000 cycles of pressure loading. The pressure is estimated using the thermoelectric voltage induced by simultaneous increase in temperature caused by a finger touch on the sensor. Additionally, a resistor‐type strain sensor fabricated using the same PDMS/PPy/GF could detect the strain up to 50%. Flexible, high performance supercapacitor used as a power supply is fabricated with electrodes of PPy/GF for its high surface area and pseudocapacitance. Furthermore, an integrated system of such fabricated multifunctional sensors and a supercapacitor on a skin‐attachable flexible substrate using liquid–metal interconnections operates well, whereas sensors are driven by the power of the supercapacitor. This study clearly demonstrates that the appropriate choice of a single functional material enables fabrication of active multifunctional sensors for pressure, temperature, and strain, as well as the supercapacitor, that could be used in wirelessly powered wearable devices.

Highly Uniform and Low Hysteresis Piezoresistive Pressure Sensors Based on Chemical Grafting of Polypyrrole on Elastomer Template with Uniform Pore Size

“…Synthesis of PPy was confirmed with FTIR (Fourier transform infrared) spectra, Raman spectroscopy, and X‐ray photoelectron spectroscopy (XPS) analysis. The FTIR data in Figure e confirms a peak at 1546 cm −1 associated with the antisymmetric ring stretching modes of PPy . The Raman peaks at 1339 and 1580 cm −1 in Figure f are associated with PPy ring stretching and CC backbone stretching of PPy, respectively .…”

Flexible Sensors—From Materials to Applications

“…Polypyrrole (PPy) is also an environmentally stable and biocompatible ECP, with a high electrical conductivity in the range 40 S/cm to 50 S/cm [156,157], and with a mechanical flexibility and solubility that makes it easy to apply on fibre surfaces through bathing [158][159][160][161], electrodeposition [161], or in-situ polymerisation [70,157,[162][163][164]. PPy has been used as conductive coating on carbon fibres and PDMS-carbon fibre bundles via electropolymerisation to create a fibre-based e-skin capable of self charge through triboelectrification effect [164].…”

“…Similarly, PPy was deposited on an elastic membrane made of PDMS fibres, obtaining a flexible strain sensor with a specific volume resistance of 448 Ω cm [162]. A more complex structure was achieved by Park et al [157] where a pressure/temperature/strain sensor and a flexible capacitor was fabricated in a single device. They used a PDMS coated microporous polypyrrole/graphene foam composite (PDMS/PPy/GF).…”

Recent Progress in Micro‐Supercapacitor Design, Integration, and Functionalization

“…The current trend for those miniaturized sensing systems is to integrate with MSCs, which can avoid the external power supply, and thus, decrease the overall volume as well as weight. For this motivation, numerous studies on sensor/MSCs self‐powered systems including photodetectors, gas sensors, and strain sensors have been reported . For instance, Kim et al reported on the fabrication of flexible MSC arrays with hybrid electrodes of MWCNT/V 2 O 5 nanowire composites, which powered the SnO 2 NW UV sensor on the same substrate.…”