Bo Weng

High-Performance Flexible All-Solid-State Supercapacitor from Large Free-Standing Graphene-PEDOT/PSS Films

Although great attention has been paid to wearable electronic devices in recent years, flexible lightweight batteries or supercapacitors with high performance are still not readily available due to the limitations of the flexible electrode inventory. In this work, highly flexible, bendable and conductive rGO-PEDOT/PSS films were prepared using a simple bar-coating method. The assembled device using rGO-PEDOT/PSS electrode could be bent and rolled up without any decrease in electrochemical performance. A relatively high areal capacitance of 448 mF cm−2 was achieved at a scan rate of 10 mV s−1 using the composite electrode with a high mass loading (8.49 mg cm−2), indicating the potential to be used in practical applications. To demonstrate this applicability, a roll-up supercapacitor device was constructed, which illustrated the operation of a green LED light for 20 seconds when fully charged.

Printing conducting polymers

Recent developments in both materials science and printing technologies have led to a rapid expansion in the field of printed conducting polymers. This review provides an overview of the most common printing methods currently in use and the material requirements of each. Examples of printed devices fabricated from a range of conducting polymers are given with an emphasis on the development of sensors.

Wholly printed polypyrrole nanoparticle-based biosensors on flexible substrate

Printing has been widely used in the sensor industry for its speed, low cost and production scalability. In this work we present a wholly-printed polypyrrole (PPy) based biosensor produced by inkjet printing bioinks composed of dispersions of PPy nanoparticles and enzymes onto screen-printed carbon electrodes. Two enzymes, horseradish peroxidase (HRP) or glucose oxidase (GoD) were incorporated into the PPy nanoparticle dispersions to impart biosensing functionality and selectivity into the conducting polymer ink. Further functionality was also introduced by deposition of a permselective ethyl cellulose (EC) membrane using inkjet printing. Cyclic voltammetry (CV) and chrono-amperometry were used to characterize the response of the PPy biosensors to H2O2 and glucose. Results demonstrated the possibility of PPy based biosensor fabrication using the rapid and low cost technique of inkjet printing. The detection range of H2O2 was found to be 10 μM-10 mM and for glucose was 1-5 mM.

Gemini surfactant doped polypyrrole nanodispersions: an inkjet printable formulation

We chemically synthesized inkjet printable polypyrrole (PPy) nanoformulations with reasonable conductivity for the first time in the presence of gemini surfactants 9BA-4-9BA (6,6′-(butane-1,4-diylbis(oxy)) bis(3-nonylbenzenesulfonic acid)) and 9B-4-9B (6,6′-(butane-1,4-diylbis(oxy)) bis(3-nonylbenzenesulfonic sodium)). Different oxidants and surfactants were investigated to optimize the surface tension, viscosity and conductivity of PPy dispersions to make it suitable for inkjet printing. Finally, a nanoformulation (maximum particle size < 200 nm) with low viscosity (9.4 mPa s), low surface tension (30.8 mN m−1) and reasonable cast conductivity (1.26 S cm−1) was obtained. This nanoformulation was printed successfully on different substrates and SEM images of a printed film on PVDF indicate that the size of the particles in the dispersion is 50 ± 5 nm. The conductivity of printed PPy/GA films on glass slides was as high as 0.7 S cm−1.

Poly(3,4-ethylenedioxythiophene): Dextran sulfate (PEDOT: DS) - A highly processable conductive organic biopolymer

A novel water-dispersible conducting polymer analogous to poly(3,4-dioxythiophene):polystyrene sulfonate (PEDOT:PSS) has been chemically synthesized in a single reaction in high yield. PEDOT:DS, a new member of the polythiophene family, is composed of a complex between PEDOT and the sulfonated polysaccharide polyanion dextran sulfate. Drop-cast films of aqueous suspensions of the material display a native conductivity of up to 7 ± 1 S cm(-1), increasing to 20 ± 2 S cm(-1) after treatment with ethylene glycol and thermal annealing. Mass ratios of the precursors NaDS and EDOT were varied from 5:1 to 2:1 and a decrease in the NaDS:EDOT ratio produces tougher, less hygroscopic films of higher conductivity. Ultraviolet-visible spectroelectrochemistry yields spectra typical of PEDOT complexes. Cyclic voltammetry reveals that PEDOT:DS is electrochemically active from -1.0 to 0.8 V vs. Ag/Ag(+) in acetonitrile, with similar characteristics to PEDOT:PSS. Water dispersions of PEDOT:DS are successfully processed by drop casting, spray coating, inkjet printing and extrusion printing. Furthermore, laser etching of dried films allows the creation of patterns with excellent definition. To assess the cytotoxicity of PEDOT:DS, L-929 cells were cultured with a polymer complex concentration range of 0.002 to 0.2 g l(-1) in cell culture medium. No significant difference is found between the proliferation rates of L-929 cells exposed to PEDOT:DS and those in plain medium after 96h. However, PEDOT:PSS shows around 25% less cell growth after 4 days, even at the lowest concentration. Taken together, these results suggest PEDOT:DS has exceptional potential as an electromaterial for the biointerface.

Efficiency of a compact elliptical planar ultra-wideband antenna based on conductive polymers

A planar antenna for ultra-wideband (UWB) applications covering the 3.1–10.6 GHz range has been designed as a test bed for efficiency measurements of antennas manufactured using polymer conductors. Two types of conductive polymers, PEDOT and PPy (polypyrrole), with very different thicknesses and conductivities have been selected as conductors for the radiating elements. A comparison between measured radiation patterns of the conductive polymers and a copper reference antenna allows to estimate the conductor losses of the two types of conductive polymers. For a 158 μm thick PPy polymer, an efficiency of almost 80% can be observed over the whole UWB spectrum. For a 7 μm thick PEDOT layer, an average efficiency of 26.6% demonstrates, considering the room for improvement, the potential of this type of versatile materials as flexible printable alternative to conductive metallic paints. The paper demonstrates that, even though the PEDOT conductivity is an order of magnitude larger than that of PPy, the thicker PPy layer leads to much higher efficiency over the whole UWB frequency range. This result highlights that high efficiency can be achieved not only through high conductivity, but also through a sufficiently thick layer of conductive polymers.

Inkjet printed conductive polymer-based beam-splitters for terahertz applications

Terahertz beam-splitters are fabricated from conductive polymers inkjet printed onto an acetate film substrate. The principle is a significant evolution of the recently proposed ultra-thin beam-splitter realized using silver conductive paint. The splitting ratios of the beam-splitters are dependent on the thickness and conductivity of the conductive polymer layer, allowing for any splitting ratio to be achieved accurately from a controlled printing process. As the processing technology of conductive polymers matures, this approach will allow for low cost and accurate fabrication of THz beam-splitters with a predefined near frequency-independent splitting ratio, in contrast to the commonly used float zone silicon wafers.

Fabrication and Characterization of Cytocompatible Polypyrrole Films Inkjet Printed from Nanoformulations Cytocompatible, Inkjet-Printed Polypyrrole Films

Inkjet printed polypyrrole (PPy) films with good uniformity and conductivity are fabricated from a stable, printable PPy nanodispersion, and the cytocompatability of these platforms is demonstrated using PC12 cells. This novel approach to fabricating PPy electrodes and films for tissue engineering and cell stimulation is particularly useful where microstructures are required.

Nanostructured conducting polymers for electrochemical sensing and biosensing

Abstract: Conducting polymers have found widespread use in the development of electrochemical sensors and biosensors. This chapter discusses the available methods for fabricating conducting polymer nanomaterials and looks at their application to electrochemical sensing and biosensing.