Electrochemical characterization of reduced graphene oxide-coated polyester fabrics

Reduced graphene oxide (RGO) coated fabrics were obtained by chemical reduction of GO on polyester (PES) fabrics. Conducting fabrics that have different applications were obtained by applying several layers of RGO. Electrochemical techniques not traditionally used for the characterization of these materials were used to test their electrical and electrochemical properties. Electrochemical impedance spectroscopy was used to measure the electrical properties. The resistance of the original PES was more than 10(11) Omega cm(2), but when coated with three RGO layers, the resistance decreased to 23.15 Omega cm(2). Phase angles changed from 90 degrees for PES and PES-GO (capacitative behavior) to 0 degrees for all the RGO coated samples (resistive behavior). Electro-activity was measured by cyclic voltammetry (CV) and scanning electrochemical microscopy. An increase in electro-activity was observed when the inactive GO was reduced to RGO. With CV an increase of electro-activity was observed with an increasing number of RGO layers. The contact between the different RGO sheets is responsible for the electric conduction in the fabrics. The techniques used showed that with only one RGO coating, the contact between the RGO sheets is not good and more coatings were needed to assure good electrical and electrochemical properties. (C) 2013 Elsevier Ltd. All rights reserved.The authors wish to thank the Spanish Ministerio de Ciencia e Innovacion (contracts CTM2010-18842-C02-02 and CTM2011-23583) and Universitat Politecnica de Valencia (Vicerrectorado de Investigacion PAID-06-10 contract 003-233) for their financial support. J. Molina is grateful to the Conselleria d'Educacio, Formacio i Ocupacio (Generalitat Valenciana) for the Programa VALi+D post-doctoral fellowship. A.I. del Rio is grateful to the Spanish Ministerio de Ciencia y TecnologRia for the FPI fellowship.Molina Puerto, J.; Fernández Sáez, J.; Inés Vilches, JC.; Del Río García, AI.; Bonastre Cano, JA.; Cases Iborra, FJ. (2013). Electrochemical characterization of reduced graphene oxide-coated polyester fabrics. Electrochimica Acta. 93:44-52. https://doi.org/10.1016/j.electacta.2013.01.071S44529

Polyaniline coated conducting fabrics : chemical and electrochemical characterization

Polyaniline coated conducting fabrics have been obtained by chemical oxidation of aniline by potassium peroxydisulfate on polyester fabrics. Two different acids have been employed to carry out the synthesis (HCl and H2SO4), obtaining the best results of conductivity with the latter one. The conducting fabrics have been characterized chemically by means of Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR), energy dispersive X-Ray (EDX) and X-ray photoelectron spectroscopy (XPS). The morphology of the coatings has been observed by means of scanning electron microscopy (SEM). The conducting properties of the fabrics have been measured by means of electrochemical impedance spectroscopy (EIS). The electrochemical characterization has been carried out by means of cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM). The conducting fabrics have also shown electrochromic properties, changing its color from green yellowish at −1 V to dark green at +2 V. The durability of the coating has been evaluated by means of washing and rubbing fastness tests.Authors thank to the Spanish Ministerio de Ciencia e Innovacion and European Union Funds (FEDER) (contract CTM2010-18842-C02-02) and Universitat Politecnica de Valencia (Primeros Proyectos de Investigacion (PAID-06-10)) for the financial support. J. Molina is grateful to the Conselleria d'Educacio (Generalitat Valenciana) for the FPI fellowship

One-step metallization of weft-knitted fabrics for wearable biaxial strain sensors

One-step direct patterning of high definition conductive tracks in textiles is realized through laser direct writing in combination with a silver organometallic ink developed in-house. Photoreduction, nano-crystallization, and sintering are accomplished in one pass under the irradiation of a CW green laser light (λ = 532 nm) at moderate intensities (I ≥ 95 mW/mm(2)). By tailoring the surface tension and viscosity of the ink, high-definition conductive tracks are formed in weft-knitted polyester-Spandex composite fabrics, well-following the laser’s profile with negligible coffee stain effect. Length resistance as low as 4 Ω/cm is measured and anisotropy of the gauge factor as high as 25 is achieved. The metallized fabric exhibits reversible and hysteresis-free electromechanical responses subject to high strains. Durability assessment qualifies that the as-metallized strain sensors are able to sustain their performance for over 5000 stretch/release cycles, demonstrating its potential applications in biaxial strain sensing and interactive smart textiles

Graphene textile smart clothing for wearable cardiac monitoring

Wearable electronics is a rapidly growing field that recently started to introduce successful commercial products into the consumer electronics market. Employment of biopotential signals in wearable systems as either biofeedbacks or control commands are expected to revolutionize many technologies including point of care health monitoring systems, rehabilitation devices, human–computer/machine interfaces (HCI/HMIs), and brain–computer interfaces (BCIs). Since electrodes are regarded as a decisive part of such products, they have been studied for almost a decade now, resulting in the emergence of textile electrodes. This study reports on the synthesis and application of graphene nanotextiles for the development of wearable electrocardiography (ECG) sensors for personalized health monitoring applications. In this study, we show for the first time that the electrocardiogram was successfully obtained with graphene textiles placed on a single arm. The use of only one elastic armband, and an “all-textile-approach” facilitates seamless heart monitoring with maximum comfort to the wearer. The functionality of graphene textiles produced using dip coating and stencil printing techniques has been demonstrated by the non-invasive measurement of ECG signals, up to 98% excellent correlation with conventional pre-gelled, wet, silver/silver-chloride (Ag / AgCl) electrodes. Heart rate have been successfully determined with ECG signals obtained in different situations. The system-level integration and holistic design approach presented here will be effective for developing the latest technology in wearable heart monitoring devices

Fully integrated rechargeable pedot : PSS energy storage device for smart textiles applications

Energievoorziening en opslag is een belangrijk onderdeel van slimme textielsystemen omdat het de vereiste energie levert om het systeem van stroom te voorzien. Deze thesis is een voortzetting van een vorige studie, en was vooral gericht op het verbeteren van de prestaties en het uiterlijk van het onderdeel door de verbetering van de fabricagetechnieken en het onderzoeken van het werkingsprincipe en mechanisme van de TESD component. De ontwikkelde component transformeerde, van de vroegste naar de nieuwste vorm, via vier verschillende en verbeterde fabricagemethoden die de prestaties en het uiterlijk van het apparaat verbeterden. De component met de naam TESD 1.2 THL is de beste vorm van ons textiel-energieopslagonderdeel tot nu toe. Uit de studie van het mechanisme werd complex gedrag van ionische en elektronische oorsprong waargenomen in het grensvlakgebied van het gebruikte geleidende polymeer, PEDOT:PSS. Een grotere verhouding van PEDOT tot PSS, met een hogere soortelijke weerstand, is wenselijk, maar verder onderzoek is nodig. Weerstand tegen wassen van het apparaat en het conceptontwerp voor de integratie van onze TESD in kleding werd ook uitgewerkt. Over het geheel genomen lieten de resultaten veelbelovend potentieel zien voor de verdere ontwikkeling van een op textiel gebaseerd energieopslagapparaat

Utilizing Diffusion and Temperature as a Means of Band-Gap Modulation for Conjugated Polymers

First, the effect of monomer feed ratios when two electroactive monomers diffuse towards each other as a means of modulating the band gap by creating different copolymers is presented. From two homopolymers, having a high and low energy band gap, a set of conjugated copolymers with different energy bang gaps were prepared in a single run using diffusion fundamentals. . Hence, a combination of the two monomers is used to generate solid state electrochromic devices of any color. Second, the preparation and characterization of conductive fabric using a conjugated polymer is introduced. The electrical properties, morphology, and the effect of temperature on conductive fabric resistance over a wide range of temperature were investigated. It was found that the conductive fabric had low sheet resistance with passage of high current. The material exhibited metallic behavior at a specific temperature due to the modulation in the band gap from the semiconductor to metal rang