Poly(3,4-ethylenedioxythiophene) Polystyrene Sulfonate Research Articles

Probing Enhanced Electrochemical Performance of Poly (3,4‐ethylenedioxy Thiophene) Encapsulated 5.3 V Spinel LiCoMnO4 Cathode for Li‐ion Batteries

AbstractHerein, the effect of poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT) coating is reported on the electrochemical properties of high voltage, 5.3 V lithium cobalt manganese oxide (LiCoMnO4, LCMO) cathodes. Scalable precipitation followed by a wet coating method is employed for the synthesis of LCMO@PEDOT. Various analytical studies are performed to validate the performance of the cathode. The cycling profile exhibits an enhanced electrochemical performance among the LCMO@PEDOT compared to that of pristine LCMO in a half‐cell configuration. Also, the LCMO@PEDOT: 0.5–3 wt.% is optimized to show better electrochemical performance. The diffusion coefficient calculated from both cyclic voltammetry and electrochemical impedance spectroscopy (EIS) exhibits an increase in the magnitude from PEDOT coating of 0.5 to 3 wt.% in the order of ≈10−12 cm2 s−1. An in‐operando X‐ray diffraction and in‐situ EIS are performed to validate the electrochemical activity. The full‐cell assembly is also fabricated with spinel Li4Ti5O12 (LTO) anode under balanced loading conditions. The LCMO@PEDOT (1–3 wt.%)/LTO exhibits better electrochemical performance compared to pristine LCMO/LTO. In addition, a temperature study of full‐cell is carried out within the range of −10 to 20 °C and compared.

Electrochemical Determination of Iron(III) in River Water by Differential Pulse Voltammetry (DPV) Using a Poly(3,4-Ethylenedioxythiophene)–Polystyrene Sulfonate co-Polymer/Gold Nanoparticle Modified Gold Microelectrode

An electrochemical sensor based upon a poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT-PSS) co-polymer film with gold nanoparticles (AuNPs) modified microelectrode is reported for the determination of Fe(III). Scanning electron microscopy images showed that the AuNPs were immobilized on gold (Au) microelectrode by formation of a nanofilm with PEDOT-PSS. The individual particles and their cluster-like aggregates provide a larger active electrochemical area and higher conductivity, which facilitates the determination of Fe(III). Electrochemical impedance spectroscopy (EIS) shows the AuNPs/PEDOT-PSS/Au microelectrode possesses high conductivity. A low detection limit of 0.01 µM Fe(III) was obtained using the modified microelectrode by differential pulse voltammetry (DPV) due to its large specific surface area, high conductivity, and the presence of more active sites. The optimized pH of the supporting acetate buffer was 2.0. The AuNPs/PEDOT-PSS/Au provided a linear range from 0.0119 μM to 7.14 μM. The modified electrode was successfully employed for the the determination of total dissolved iron in river water from Three Gorges with satisfactory results.

Organic Light-Emitting Diodes with Electrospun Electrodes for Double-Side Emissions.

Transparent conductive electrodes (TCE) obtained by the electrospinning method and gold covered were used as cathodes in the organic light-emitting diodes (OLEDs) to create double side-emission. The electro-active nanofibers of poly(methyl methacrylate) (PMMA) with diameters in the range of several hundreds of nanometers, were prepared through the electrospinning method. The nanofibers were coated with gold by sputtering deposition, maintaining optimal transparency and conductivity to increase the electroluminescence on both electrodes. Optical, structural, and electrical measurements of the as-prepared transparent electrodes have shown good transparency and higher electrical conductivity. In this study, two types of OLEDs consisting of indium tin oxide (ITO)/ poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT-PSS)/ Ir(III) complex (8-hydroxyquinolinat bis(2-phenylpyridyl) iridium-IrQ(ppy)2 20 wt% embedded in N, N'-Dicarbazolyl-4,4'-biphenyl (CBP) sandwich structure and either gold-covered PMMA electrospun nanoweb (OLED with electrospun cathode) were fabricated together with a similar structure containing thin film gold cathodes (OLED with thin film cathode). The luminance-current-voltage characteristics, the capacitance-voltage, and the electroluminescence properties of these OLEDs were investigated.

Guide to Leveraging Conducting Polymers and Hydrogels for Direct Current Stimulation

AbstractThe tunable electrical properties of conducting polymers (CPs), their biocompatibility, fabrication versatility, and cost‐efficiency make them an ideal coating material for stimulation electrodes in biomedical applications. Several biological processes like wound healing, neuronal regrowth, and cancer metastasis, which rely on constant electric fields, demand electrodes capable of delivering direct current stimulation (DCs) for long times without developing toxic electrochemical reactions. Recently, CPs such as poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT/PSS) have demonstrated outstanding capability for delivering DCs without damaging cells in culture while not requiring intermediate buffers, contrary to the current research setups relying on noble‐metals and buffering bridges. However, clear understanding of how electrode design and CP synthesis influence DCs properties of these materials has not been provided until now. This study demonstrates that various PEDOT‐based CP coatings and hydrogels on rough electrodes can deliver DCs without substantial changes to the electrode and the noticeable development of chemical by‐products depending on the electrode area and polymer thickness. A comprehensive analysis of the tested coatings is provided according to the desired application and available resources, alongside a proposed explanation for the observed electrochemical behavior. The CPs tested herein can pave the way toward the widespread implementation of DCs as a therapeutic stimulation paradigm.

A Highly Sensitive Electrochemical Sensor for Cd2+ Detection Based on Prussian Blue-PEDOT-Loaded Laser-Scribed Graphene-Modified Glassy Carbon Electrode

Heavy metal ion pollution has had a serious influence on human health and the environment. Therefore, the monitoring of heavy metal ions is of great practical significance. In this work, we describe the development of an electrochemical sensor to detect cadmium (Cd2+) using a Prussian blue (PB), poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT)-loaded laser-scribed graphene (LSG) nanocomposite-modified glassy carbon electrode (GCE). In this nanocomposite material, we successfully brought together the advantages of an extraordinarily large surface area. The accumulation of PB nanoparticles results in an efficient electrochemical sensor with high sensitivity and selectivity and fast detection ability, developed for the trace-level detection of Cd2+. Electrochemical features were explored via cyclic voltammetry (CV), whereas the stripping voltammetry behavior of modified electrodes was analyzed by utilizing differential pulse voltammetry. Compared with bare GCE, the LSG/PB-PEDOT/GCE modified electrode greatly increased the anodic stripping peak currents of Cd2+. Under the optimized conditions, the direct and facile detection of Cd2+ was achieved with a wide linear range (1 nM–10 µM) and a low LOD (0.85 nM).

Implantable Organic Artificial Synapses Exhibiting Crossover between Depressive and Facilitative Plasticity Response

AbstractOrganic neuromorphic devices mimic signal processing features of biological synapses, with short‐term plasticity, STP, modulated by the frequency of the input voltage pulses. Here, an artificial synapse, made of intracortical microelectrodes, is demonstrated that exhibits either depressive or facilitative STP. The crossover between the two STP regimes is controlled by the frequency of the input voltage. STP features are described with an equivalent circuit where an inductance component is introduced in parallel with the RC circuit associated with poly(3,4‐ethylenedioxythiophene)/polystyrene sulfonate (PEDOT/PSS)||electrolyte interface. The proposed RLC circuit explains the physical origin of the observed STP and its two timescales in terms of charge build up in PEDOT/PSS.

SIROF stabilized PEDOT/PSS allows biocompatible and reversible direct current stimulation capable of driving electrotaxis in cells

Electrotaxis is a naturally occurring phenomenon in which ionic gradients dictate the directed migration of cells involved in different biological processes such as wound healing, embryonic development, or cancer metastasis. To investigate these processes, direct current (DC) has been used to generate electric fields capable of eliciting an electrotactic response in cells. However, the need for metallic electrodes to deliver said currents has hindered electrotaxis research and the application of DC stimulation as medical therapy. This study aimed to investigate the capability of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT/PSS) on sputtered iridium oxide film (SIROF) electrodes to generate stable direct currents. The electrochemical properties of PEDOT/PSS allow ions to be released and reabsorbed depending on the polarity of the current flow. SIROF stabilized PEDOT/PSS electrodes demonstrated exceptional stability in voltage and current controlled DC stimulation for periods of up to 12 hours. These electrodes were capable of directing cell migration of the rat prostate cancer cell line MAT-LyLu in a microfluidic chamber without the need for chemical buffers. This material combination shows excellent promise for accelerating electrotaxis research and facilitating the translation of DC stimulation to medical applications thanks to its biocompatibility, ionic charge injection mechanisms, and recharging capabilities in a biological environment.

Facile Fabrication of a Stretchable and Flexible Nanofiber Carbon Film-Sensing Electrode by Electrospinning and Its Application in Smart Clothing for ECG and EMG Monitoring

In this study, a carbon electrode was synthesized from carbon black (CB), reduced graphene oxide (rGO), and polyurethane (PU) and subsequently used as the collector for electrospinning. During electrospinning, nanofibers were deposited on the carbon film collector. The carbon electrode and the deposited nanofibers together formed a nanofiber carbon electrode. Finally, a stretchable and flexible nanofiber membrane-sensing electrode was successfully developed and applied in smart clothing for ECG and EMG monitoring. The nanofibers were generated from polyvinylidene difluoride (PVDF) and poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT/PSS) via mixing and electrospinning. The addition of a conductive PEDOT/PSS polymer inhibited the formation of beads on the fiber and enhanced the integrity as well as the electrical conductivity of the fiber. In addition, a CB/rGO carbon film was used as the electrospinning collector. The addition of a dispersant to the carbon film improved its electrical conductivity as well as its stretchability. The results show that the nanofiber carbon electrode prepared by electrospinning exhibits a high electrical conductivity (surface resistance = 2.5 × 101 Ω/sq), high mechanical durability (a stable circuit was maintained after 3000 repeated uses), and a hydrophobic surface (water contact angle = 146°). Compared with a traditional commercial wet electrode (Ag/AgCl), the nanofiber carbon electrode developed in this study exhibited good contact with human skin and excellent durability. These merits make the nanofiber carbon electrode suitable for long-term biological signal recording. Furthermore, such an electrode can be integrated into wearable systems for healthcare monitoring.

Control of Reactions on Bipolar Electrodes Using Ion-Selective Membranes

Bipolar electrochemistry is promising in realizing simultaneous multiplexed detection. In open bipolar systems, a potential gradient is formed in a solution. When an isolated electrode (bipolar electrode: BPE) that is not in contact with an external device is placed in the potential gradient, interfacial potential difference develops between the BPE and the solution (Figure 1A). As a result, oxidation and reduction reactions occur simultaneously on both poles (Figure 1B) [1]. The progress of the reduction reaction on the cathodic pole can be measured by coupling the reaction with a reaction that generates electrochemiluminescence (ECL) [2]. However, a problem with this method is that the interfacial potential difference on the BPE is not precisely controlled. In other words, the potential profile with respect to the electrode potential changes (Figure 1C). To solve this problem, we used an ion-selective membrane (ISM) on a part of the BPE. The ISM has an effect to fix the interfacial potential difference at the location without current generation through the interface (Figure 1D).Arrays of BPEs were formed with gold and Na+ ISM was formed on a part of each BPE. The surface of the BPE was insulated with a polyimide layer except for the anodic and cathodic poles and the active area of the ISM. To form the ISM, a layer of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT/PSS) was first coated on an exposed area of the BPE. The Na+ ISM was formed on the PEDOT/PSS layer. The solution to form the ISM contained 43.97 wt% polyvinyl chloride (PVC) dissolved in 1 mL tetrahydrofuran (THF). 53.38 wt% of nitrophenyl octyl ether (NPOE), 2.04 wt% of sodium ionophore X, and 0.61 wt% (w/w) of sodium tetrakis(4-fluorophenyl)borate (NaTFPB) were added to the PVC solution and mixed well. After forming the ISM, its peripheries were fixed with a silicone adhesive.In the experimental setup shown in Figure 1A, platinum wires (diameter: 0.5 mm) were used for the driving electrodes. The distance between the driving electrodes was 30 mm. To cause the ECL reaction, 10 mM phosphate buffer solution (pH 6.9) containing 5.0 mM tripropylamine (TPA) and 1.0 mM [Ru(bpy)3]2+ was used. Oxygen dissolved in the solution was used as an analyte. The experiments were conducted at 25°C.To control the potential of the BPEs, we previously used Ag/AgCl for the potential control. However, a problem was that current flowed through the non-polarizable metal/solution interface, affecting the ECL intensity. With regard to this, the ISM is superior because current does not flow. The effect of placing the ISM on a part of the BPE was first examined using BPEs of the same length and changing the location of the ISM (Figure 2). The ion selective electrode (ISE) was effective and the ECL intensity changed by changing the location of the ISE. The effect of the ISM was also demonstrated using folded double BPE structures with the ISM formed at either or both ends. Brighter ECL was observed with the folded structure compared with a single BPE. From these experiments, the effect of placing the ISM on BPEs was clearly observed. As an application to biosensing, we also tested the detection of glucose by immobilizing glucose oxidase and osmium polymer on the cathodic pole. The ECL was also observed accompanying the production of hydrogen peroxide by glucose oxidase and following the reduction of hydrogen peroxide.The effect of placing the ISM was also examined in closed bipolar systems. In the closed bipolar systems, solutions in the cathode and anode side are separated in different compartments. In this study, 15 mm-long electrodes were used and the electrodes extended in the two compartments. The anodic pole was exposed to the solution for ECL, whereas the cathodic pole was immersed in a Na2SO4 solution. A voltage (2.4 V) was applied between the driving electrodes immersed at the end of the solutions. The brightest ECL was observed on the BPE with the ISM nearest to the cathodic pole. The result indicates that the ISM is also effective in controlling the potential for closed bipolar systems.[1] S. E. Fosdick, K. N. Knust, K. Scida, R. M. Crooks. Bipolar electrochemistry. Angewandte Chemie International Edition, 52 (2013) 10438-10456. doi:10.1002/anie.201300947[2] K. F. Chow, F. Mavré, R. M. Crooks. Wireless electrochemical DNA microarray sensor. Journal of the American Chemical Society, 130 (2008) 7544-7545. doi:10.121/ja802013q Figure 1

Modulation of Neuronal Cell Affinity on PEDOT-PSS Nonwoven Silk Scaffolds for Neural Tissue Engineering.

Peripheral nerve injury is a common consequence of trauma with low regenerative potential. Electroconductive scaffolds can provide appropriate cell growth microenvironments and synergistic cell guidance cues for nerve tissue engineering. In the present study, electrically conductive scaffolds were prepared by conjugating poly (3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT-PSS) or dimethyl sulfoxide (DMSO)-treated PEDOT-PSS on electrospun silk scaffolds. Conductance could be tuned by the coating concentration and was further boosted by DMSO treatment. Analogue NG108-15 neuronal cells were cultured on the scaffolds to evaluate neuronal cell growth, proliferation, and differentiation. Cellular viability was maintained on all scaffold groups while showing comparatively better metabolic activity and proliferation than neat silk. DMSO-treated PEDOT-PSS functionalized scaffolds partially outperformed their PEDOT-PSS counterparts. Differentiation assessments suggested that these PEDOT-PSS assembled silk scaffolds could support neurite sprouting, indicating that they show promise to be used as a future platform to restore electrochemical coupling at the site of injury and preserve normal nerve function.

Improving the power performance of urine-fed microbial fuel cells using PEDOT-PSS modified anodes

The need for improving the energy harvesting from Microbial Fuel Cells (MFCs) has boosted the design of new materials in order to increase the power performance of this technology and facilitate its practical application. According to this approach, in this work different poly(3,4-ethylenedioxythiophene)-polystyrenesulfonate (PEDOT-PSS) modified electrodes have been synthesised and evaluated as anodes in urine-fed MFCs. The electrochemical synthesis of PEDOT-PSS was performed by potentiostatic step experiments from aqueous solution at a fixed potential of 1.80 V (vs. a reversible hydrogen electrode) for different times: 30, 60, 120 and 240 s. Compared with other methods, this technique allowed us not only to reduce the processing time of the electrodes but also better control of the chemical composition of the deposited polymer and therefore, obtain more efficient polymer films. All modified anodes outperformed the maximum power output by MFCs working with the bare carbon veil electrode but the maximum value was observed when MFCs were working with the PEDOT-PSS based anode obtained after 30 s of electropolymerisation (535.1 µW). This value was 24.3% higher than using the bare carbon veil electrode. Moreover, the functionality of the PEDOT-PSS anodes was reported over 90 days working in continuous mode.

A simultaneous optical and electrical in-vitro neuronal recording system to evaluate microelectrode performance.

ObjectivesIn this paper, we aim to detail the setup of a high spatio-temporal resolution, electrical recording system utilising planar microelectrode arrays with simultaneous optical imaging suitable for evaluating microelectrode performance with a proposed ′performance factor′ metric.MethodsTechniques that would facilitate low noise electrical recordings were coupled with voltage sensitive dyes and neuronal activity was recorded both electrically via a customised amplification system and optically via a high speed CMOS camera. This technique was applied to characterise microelectrode recording performance of gold and poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT/PSS) coated electrodes through traditional signal to noise (SNR) calculations as well as the proposed performance factor.ResultsNeuronal activity was simultaneously recorded using both electrical and optical techniques and this activity was confirmed via tetrodotoxin application to inhibit action potential firing. PEDOT/PSS outperformed gold using both measurements, however, the performance factor metric estimated a 3 fold improvement in signal transduction when compared to gold, whereas SNR estimated an 8 fold improvement when compared to gold.ConclusionThe design and functionality of a system to record from neurons both electrically, through microelectrode arrays, and optically via voltage sensitive dyes was successfully achieved.SignificanceThe high spatiotemporal resolution of both electrical and optical methods will allow for an array of applications such as improved detection of subthreshold synaptic events, validation of spike sorting algorithms and a provides a robust evaluation of extracellular microelectrode performance.

Control of Reactions on Bipolar Electrodes Using Ion-Selective Membranes

IntroductionBipolar electrochemistry is an attractive technique to realize simultaneous multiplexed detection. In bipolar electrochemical systems, a potential gradient is formed in a solution. When an isolated electrode (bipolar electrode: BPE) that is not in contact with an external device is placed in the potential gradient, potential difference is generated at the interface between the BPE and the solution (Figure 1(A)), which can be a motive force to make anodic and cathodic reactions to proceed on the BPE (Figure 1(B)) [1]. The progress of reduction reactions on the cathodic pole can be measured by coupling the reaction with electrochemiluminescence (ECL) [2]. Although the simple single electrode configuration is attractive in realizing a large array of BPEs, an issue is that the interfacial potential difference on the BPE is not controlled intentionally. In other words, the potential profile in the solution can vary as expressed by 1, 2, and 3, although the potential difference between the two poles is the same for all cases (Figure 1(C)). To solve this problem, we used an ion-selective membrane (ISM) on a part of the BPE. The ISM has an effect to fix the interfacial potential difference there without current generation through the interface (Figure 1(D)). Method Arrays of BPEs were formed with platinum (Pt) or gold (Au). An ISM was formed on a part of each BPE. The surface of the BPE was insulated with polyimide layer except for the anodic and cathodic poles and the active area of the ISM. We previously tested the use of thin-film Ag/AgCl instead of the ISM. However, a problem was that current flowed through the interface due to its non-polarized nature, affecting the ECL intensity. With regard to this, current does not flow through the ISM/solution interface. The location of the ISM was changed with BPEs of the same length (Figure 2(A)). Otherwise, BPEs of different lengths were fabricated, and the location of the ISM was kept constant between the ISM and the cathodic pole (Figure 2(B)).The active areas on the BPEs were cleaned and the cleanliness was checked by taking cyclic voltammograms (CV) in a solution containing 100 mM KCl and 10 mM K3[Fe(CN)6]. To form the ISM, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT/PSS) was first coated on an exposed area of the BPE. To form the ISM, 20 µl of Na+ ionophore cocktail containing 89.5% 2-Nitrophenyl octyl ether, 10.0% sodium ionophore II, and 0.5% sodium tetraphenylborate (w/w) (Sigma-Aldrich (Japan)) was dissolved in 79.3% polyvinyl chloride (PVC) and tetrahydrofuran (PVC/THF) solution. The solution was dropped onto the PEDOT/PSS layer to form the ISM and was dried.Figure 3 shows the setup used for the experiment. Pt wires (diameter: 0.5 mm) were used for the driving electrodes. The distance between the driving electrodes was 30 mm. For ECL, 10 mM PBS (pH 6.9) containing 5.0 mM tripropylamine (TPA) and 1.0 mM [Ru(bpy)3]2+ was used. As an analyte, oxygen dissolved in the solution was used. To change the interfacial potential difference at the ISM, Na+ ions of different concentrations were added to the solution. Before injecting the solution in the reaction chamber, the solution was stirred for at least 30 min to saturate air. Pictures of ECL were taken immediately after the application of the voltage with 60 s exposure. The experiments were conducted at 25°C. Results and Conclusions The potential of the ISM was checked using a BPE with an ISM by measuring the potential in NaCl solutions of various concentrations with respect to a commercial liquid junction Ag/AgCl electrode. Figure 4 shows the dependence of the potential of the ISE on the concentration of Na+ ions. The slope was 59.0 mV/decade, which was very close to the value expected from the Nernst equation. The effect of placing the ISM on a part of the BPE was investigated using BPEs of the same length. ECL intensity changed depending on the location of the ISM (Figure 5). Figure 6 shows ECL observed using BPEs of different length maintaining the distance between ISM and the cathodic pole. In both cases, the effect of placing the ISM was clearly observed and the ECL intensity was strongest when the distance between the ISM and the anodic pole is longer. These results indicate that the ECL intensity can actually be controlled by the ISM. We have tested other electrode configurations. The results will also be presented.The potential control developed in this study is also effective to control the electrode potentials in closed BPE systems in which solutions are separated in different compartments.

Power Factor of One Molecule Thick Films and Length Dependence.

There is a rapidly increasing interest in organic thin film thermoelectrics. However, the power factor of one molecule thick organic film, the self-assembled monolayer (SAM), has not yet been determined. This study describes the experimental determination of the power factor in SAMs and its length dependence at an atomic level. As a proof-of-concept, SAMs composed of n-alkanethiolates and oligophenylenethiolates of different lengths are focused. These SAMs were electrically and thermoelectrically characterized on an identical junction platform using a liquid metal top-electrode, allowing the straightforward estimation of the power factor of the monolayers. The results show that the power factor of the alkyl SAMs ranged from 2.0 × 10–8 to 8.0 × 10–12 μW m–1 K–2 and exhibited significant negative length dependence, whereas the conductivity and thermopower of the conjugated SAMs are the two opposing factors that balance the power factor upon an increase in molecular length, exhibiting a maximum power factor of 3.6 × 10–8 μW m–1 K–2. Once correction factors about the ratio of effective contact area to geometrical contact area are considered, the values of power factors can be increased by several orders of magnitude. With a newly derived parametric semiempirical model describing the length dependence of the power factor, it is investigated that one molecule thick films thinner than 10 nm composed of thiophene units can yield power factors rivaling those of famed organic thermoelectric materials based on poly(3,4-ethylenedioxythiophene)/polystyrenesulfonate (PEDOT/PSS) and polyaniline/graphene/double-walled carbon nanotube. Furthermore, how the transition of the transport regime from tunneling to hopping as molecules become long affects power factors is examined.

Research of a Novel 3D Printed Strain Gauge Type Force Sensor.

A 3D printed force sensor with a composite structure developed by combining digital light processing (DLP) based printing and inkjet printing technologies is described in this paper. The sensor has cost effectiveness and time-saving advantages compared to the traditional sensor manufacturing process. During this work, the substrate of the force sensor was printed by a DLP based 3D printer using a transparent high-temperature resin, and the strain gauge of the force sensor was inkjet printed using poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT/PSS) conductive ink. Finite element (FE) simulation was conducted to find the print origin of the strain gauge. The relationship between the mechanical properties of the post-cured resin and the curing time was investigated and the resistance of the printed strain gauges was characterized to optimize process parameters. Afterward, the force sensor was characterized. Experimental results show that the sensitivity of the sensor is 2.92% N−1 and the linearity error is 3.1485% full scale (FS) within the range from 0 mN–160 mN, and the effective gauge factor of the strain gauge is about 0.98. The resistance drifting is less than 0.004 kΩ within an hour. These figures prove that the device can perform as a force sensor and 3D printing technology may have great applied potential in sensor fabrication.

Does Impedance Matter When Recording Spikes With Polytrodes?

Extracellular microelectrodes have been widely used to measure brain activity, yet there are still basic questions about the requirements for a good extracellular microelectrode. One common source of confusion is how much an electrode’s impedance affects the amplitude of extracellular spikes and background noise. Here we quantify the effect of an electrode’s impedance on data quality in extracellular recordings, which is crucial for both the detection of spikes and their assignment to the correct neurons. This study employs commercial polytrodes containing 32 electrodes (177 μm2) arranged in a dense array. This allowed us to directly compare, side-by-side, the same extracellular signals measured by modified low impedance (∼100 kΩ) microelectrodes with unmodified high impedance (∼1 MΩ) microelectrodes. We begin with an evaluation of existing protocols to lower the impedance of the electrodes. The poly (3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT-PSS) electrodeposition protocol is a simple, stable, and reliable method for decreasing the impedance of a microelectrode up to 10-fold. We next record in vivo using polytrodes that are modified in a ‘chess board’ pattern, such that the signal of one neuron is detected by multiple coated and non-coated electrodes. The performance of the coated and non-coated electrodes is then compared on measures of background noise and amplitude of the detected action potentials. If the proper recording system is used, then the impedance of a microelectrode within the range of standard polytrodes (∼0.1 to 2 MΩ) does not greatly affect data quality and spike sorting. This study should encourage neuroscientists to stop worrying about one more unknown.

Highly Stable and Efficient Lignin‐PEDOT/PSS Composites for Removal of Toxic Metals

AbstractA hybrid biopolymer/electronic polymer electrode is demonstrated here to extract metal ions, in this case lead, from water. The hybrid material consists of poly(3,4‐ethylenedioxythiophene)/polystyrene sulfonate (PEDOT/PSS) and the biopolymer lignin (LG) and is prepared by a simple one‐step galvanostatic polymerization from aqueous solution. The hybrid material is characterized by cyclic voltammetry, electrochemical quartz microbalance, X‐ray photoelectron spectroscopy, and scanning electron microscopy techniques. The electrochemical and spectroscopic results confirm that lead ions can be adsorbed on the composites films from a neutral solution of lead ions by applying a negative potential and subsequently desorbed from the hybrid films by applying positive potential. The adsorption capacity for lead ions on PEDOT/PSS is 245.5 mg g−1 and is almost doubled to 452.8 mg g−1 by incorporating LG into PEDOT/PSS.

Electronic Transport and Anisotropic Conductivity Behavior on PEDOT:PSS Nanoribbons and Nanostructuring Modification by Atomic Force Microscope Nanoshaving

Nanoribbons of organic semiconductor salts, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT-PSS), were deposited on silicon dioxide (SiO2) by the electrospinning technique. It is possible to “shave” or mechanically displace small regions of the polymer nanoribbon by using atomic force microscopy (AFM) nanolithography techniques such as nanoshaving, leaving swaths of the surface cut to the depth of thickness of the nanoribbon. By placing the nanoribbon between two electrode pads with a 10 μm gap, for the first time was performed nanoshaving on the nanoribbon by removing portions of PEDOT-PSS and simultaneously in-situ transport measurement properties of the nanoribbon's dependence on the remaining cross section, showed evidence of anisotropic nature of the conductivity of PEDOT-PSS nanoribbons.

PEDOT-PSS embedded comb copolymer membranes with improved CO2 capture

Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT-PSS) is a widely used conductive polymer in various electronic devices. Here we report the first use of PEDOT-PSS to enhance CO2 capture performance of all-polymeric membranes. Specifically, an amphiphilic comb copolymer, i.e. poly(2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] ethyl methacrylate)-poly(oxyethylene methacrylate) (PBEM-POEM or PBE), was synthesized to disperse PEDOT-PSS chains. Isolated and aggregated PEDOT-PSS transformed into an interconnected network structure upon combination with PBE, due to specific interactions. Incorporation of PEDOT-PSS generated a facile pathway for enhanced diffusive transport, resulting in improved CO2 and N2 permeability. However, CO2 permeability increased more significantly due to enhanced CO2 solubility, resulting in slight increase in CO2/N2 selectivity. The PBE membrane containing PEDOT-PSS 5wt% showed the highest performance with a CO2 permeability of 59.6 Barrer and CO2/N2 selectivity of 77.4. The performance of PBE/PEDOT-PSS membranes was very close to the 2008 Robeson upper bound and much higher than those of PBE/PEDOT, PBE/PSS and commercial PEBAX membranes.

Compressible, electrically conductive, fibre-like, three-dimensional PEDOT-based composite aerogels towards energy storage applications

Three types of compressible, electrically conductive aerogels have been developed in this study using poly(3,4-ethylenedioxythiophene) - polystyrene sulfonate (PEDOT-PSS). The crosslinking between PEDOT-PSS and polyethylene oxide (PEO) promoted the formation of welded fibre-like morphology, which was explained through the purpose-designed experiment and characterization. Single-walled carbon nanotubes (SWCNTs) were added to further improve the electrical conductivity and thus the electrochemical performance. The PEDOT-PSS/PEO/SWCNT aerogel was used to fabricate a flexible supercapacitor which exhibited a specific capacitance of 362 F g−1 at a scan rate of 20 mV s−1; it demonstrated an energy density of 67.7 Wh kg−1 and a power density of 13.5 kW kg−1 at 100 mV s−1 with 0–1.8 V potential window. When bent at 60°, the supercapacitor exhibited 318 F g−1 at 100 mV s−1. The flexible supercapacitor showed a 94.6% retention after 5000 cycles at 5 A g−1.