Antimony tin oxide (ATO) screen-printed electrodes and their application to spectroelectrochemistry

Spectroelectrochemistry studies spectral changes as a function of applied potential or current. While there is no standard experimental setup, transparent electrodes are most typically used in transmission mode. Working in reflection mode forces light across the sample twice, resulting in higher sensitivities, but in turn requires the use of highly reflective electrodes. Here we present the production and characterization of screen-printed electrodes made from different antimony tin oxide (ATO) conducting particles. The resulting electrodes display excellent spectroelectrochemical properties, such as reflectivities up to 20 times higher than conventional graphite screen-printed electrodes, but with comparable electron transfer rates. These electrodes represent an attractive alternative to conventional materials and widen the choice of suitable electrode materials for electrochemistry in general and spectroelectrochemistry in particularFEDER funds managed by the Catalan Secretary of Universities and Research through project PROD-0000114 (Enterprise and Knowledge, Industry Department, Generalitat de Catalunya)

Rapid prototyping of electrochemical lateral flow devices: stencilled electrodes

A straightforward and very cost effective method is proposed to prototype electrodes using pressure sensitive adhesives (PSA) and a simple cutting technique. Two cutting methods, namely blade cutting and CO2 laser ablation, are compared and their respective merits are discussed. The proposed method consists of turning the protective liner on the adhesive into a stencil to apply screen-printing pastes. After the electrodes have been printed, the liner is removed and the PSA can be used as a backing material for standard lateral flow membranes. We present the fabrication of band electrodes down to 250 μm wide, and their characterization using microscopy techniques and cyclic voltammetry. The prototyping approach presented here facilitates the development of new electrochemical devices even if very limited fabrication resources are available. Here we demonstrate the fabrication of a simple lateral-flow device capable of determining glucose in blood. The prototyping approach presented here is highly suitable for the development of novel electroanalytical tools.This work has been funded by the Spanish Ministry of Economy through the DADDi2 project (Grant TEC2013-48506). MK acknowledges funding through the Beatriu de Pinós program (BP-DGR-2013), supported by the Secretary for Universities and Research of the Ministry of Economy and Knowledge of the Government of Catalonia and the Cofund programme of the Marie Curie Actions of the 7th R&D Framework Programme of the European Union. We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)Peer reviewe

Design and development of a self-powered electrochromic biosensor

Las tendencias actuales en química analítica buscan desarrollar dispositivos de sensado más sencillos y con un coste más asequible. El uso de materiales electrocrómicos permite la fabricación de sensores electroquímicos que utilizan el cambio de color como medio para reducir la instrumentación requerida. Aunque muchos compuestos químicos usados en electroanálisis exhiben propiedades electrocrómicas, la inclusión de este tipo de materiales en la fabricación de sensores analíticos electrocrómicos está todavía en una fase muy inicial. Esta tesis se centra en el desarrollo de un nuevo tipo de dispositivos analíticos basados en el uso de materiales electrocrómicos, lo que reduce al mínimo los componentes requeridos y elimina la necesidad de usar electrónicas basadas en silicio. Primero se presenta el principio de funcionamiento de los sensores electrocrómicos autoalimentados, demostrando cómo con la geometría apropiada es posible obtener una plataforma de sensado capaz de proporcionar una lectura cuantitativa de la concentración del analito. Los datos experimentales obtenidos se combinaron con el uso de simulaciones matemáticas para desarrollar un modelo numérico que permite tener un mayor conocimiento del comportamiento del dispositivo. Además, las simulaciones se han utilizado como herramienta de diseño para mejorar el rendimiento de futuros dispositivos electrocrómicos. También se formularon nuevos materiales en forma de pastas para serigrafía que permiten substituir ciertos componentes del dispositivo tales como el material electrocrómico o el electrolito. Estos materiales han sido utilizados en la última parte de la tesis para fabricar un sensor electrocrómico totalmente impreso capaz de proveer resultados cuantitativos sin la ayuda de un dispositivo externo de lectura.Current trends in analytical chemistry aim at developing simpler and more affordable sensing devices. Electrochromic materials enable the fabrication of electrochemical sensors that exploit colour changes as a means to reduce instrumentation requirements. Although many chemical compounds used in electroanalysis exhibit electrochromic properties, the inclusion of these materials in the construction of electrochromic analytical sensors has begun to emerge only recently. This thesis focuses on the development of a new type of analytical devices relying on the use of electrochromic materials, reducing to a minimum the required components, and removing the need for silicon-based electronics. First, the working principle of self-powered electrochromic sensors is presented, demonstrating how with the appropriate geometry it is possible to obtain a sensing platform capable of providing a quantitative readout of the analyte concentration. The experimental data obtained are combined with the use of numerical simulations to develop a mathematical model that helps to have a further understanding of the behaviour of the device. Moreover, these simulations were used as a design tool to improve the performance of future electrochromic devices. New materials in the form of screen-printing pastes have also been formulated to substitute certain components of the device such as the electrochromic material or the electrolyte. These materials were used in the last part of the thesis to manufacture a fully printed electrochromic sensor able to provide quantitative results without the aid of an external signaling device

A self-powered skin-patch electrochromic biosensor

One of the limitations of many skin-patch wearable sensors today is their dependence on silicon-based electronics, increasing their complexity and unit cost. Self-powered sensors, in combination with electrochromic materials, allow simplifying the construction of these devices, leading to powerful analytical tools that remove the need for external detection systems. This work describes the construction, by screen-printing, of a self-powered electrochromic device that can be adapted for the determination of metabolites in sweat by the naked eye in the form of a 3 × 15 mm colour bar. The device comprises a lactate oxidase and osmium-polymer -based anode connected to a coplanar 3 × 15 mm Prussian Blue, PB, cathode printed over a transparent poly(3,4-ethylenedioxythiophene) polystyrene sulfonate, PEDOT:PSS electrode. An ion-gel composed of Poly(vinylidene fluoride-co-hexafluoropropylene), PVDF-co-HFP, a gelling agent, and ionic liquid 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate, EMIM-Tf, effectively separates the cathode display from the biosensing anode, protecting it from the sample. Despite its cathodic electrochromism, the PEDOT:PSS has a transmission above 90% and does not mask the Prussian Blue colour change because the cathode does not operate below 0 V vs Ag/AgCl at any time. The sensor displays lactate concentrations in the range of 0-10 mM over the length of the electrochromic display, which has a contrast ratio of 1.43. Although full response takes up to 24 min, 85% of the colour change is displayed within 10 min

Design and development of a self-powered electrochromic biosensor

Las tendencias actuales en química analítica buscan desarrollar dispositivos de sensado más sencillos y con un coste más asequible. El uso de materiales electrocrómicos permite la fabricación de sensores electroquímicos que utilizan el cambio de color como medio para reducir la instrumentación requerida. Aunque muchos compuestos químicos usados en electroanálisis exhiben propiedades electrocrómicas, la inclusión de este tipo de materiales en la fabricación de sensores analíticos electrocrómicos está todavía en una fase muy inicial. Esta tesis se centra en el desarrollo de un nuevo tipo de dispositivos analíticos basados en el uso de materiales electrocrómicos, lo que reduce al mínimo los componentes requeridos y elimina la necesidad de usar electrónicas basadas en silicio. Primero se presenta el principio de funcionamiento de los sensores electrocrómicos autoalimentados, demostrando cómo con la geometría apropiada es posible obtener una plataforma de sensado capaz de proporcionar una lectura cuantitativa de la concentración del analito. Los datos experimentales obtenidos se combinaron con el uso de simulaciones matemáticas para desarrollar un modelo numérico que permite tener un mayor conocimiento del comportamiento del dispositivo. Además, las simulaciones se han utilizado como herramienta de diseño para mejorar el rendimiento de futuros dispositivos electrocrómicos. También se formularon nuevos materiales en forma de pastas para serigrafía que permiten substituir ciertos componentes del dispositivo tales como el material electrocrómico o el electrolito. Estos materiales han sido utilizados en la última parte de la tesis para fabricar un sensor electrocrómico totalmente impreso capaz de proveer resultados cuantitativos sin la ayuda de un dispositivo externo de lectura.Current trends in analytical chemistry aim at developing simpler and more affordable sensing devices. Electrochromic materials enable the fabrication of electrochemical sensors that exploit colour changes as a means to reduce instrumentation requirements. Although many chemical compounds used in electroanalysis exhibit electrochromic properties, the inclusion of these materials in the construction of electrochromic analytical sensors has begun to emerge only recently. This thesis focuses on the development of a new type of analytical devices relying on the use of electrochromic materials, reducing to a minimum the required components, and removing the need for silicon-based electronics. First, the working principle of self-powered electrochromic sensors is presented, demonstrating how with the appropriate geometry it is possible to obtain a sensing platform capable of providing a quantitative readout of the analyte concentration. The experimental data obtained are combined with the use of numerical simulations to develop a mathematical model that helps to have a further understanding of the behaviour of the device. Moreover, these simulations were used as a design tool to improve the performance of future electrochromic devices. New materials in the form of screen-printing pastes have also been formulated to substitute certain components of the device such as the electrochromic material or the electrolyte. These materials were used in the last part of the thesis to manufacture a fully printed electrochromic sensor able to provide quantitative results without the aid of an external signaling device

Electrochromic sensors: innovative devices enabled by spectroelectrochemical methods

Electrochromic sensors are electrochemical devices exploiting colour changes as a means to simplify device construction and instrumentation requirements. Despite their advantages, electrochromic sensors have begun to emerge only recently. Mainly based on the works appeared in the literature over the past 2 years, we describe the construction and operation of these devices. A simple framework is proposed to understand and classify these devices more easily. This is based on the sensor architecture, their power source, and how information is displayed. Despite their youth, electrochromic sensors are already demonstrated in a number of applications, mostly related to health and point of care devices.Peer reviewe

Biosensor inalámbrico, portátil y reutilizable

Biosensor inalámbrico, portátil y reutilizable. La presente invención se refiere a un dispositivo biosensor para la determinación de analitos, no invasivo mediante la visualización de un cambio de color, y a partir de una muestra de líquido. La presente invención se enmarca en el ámbito dispositivos para la salud, control durante realización de deporte, la seguridad laboral y la industria alimentaria.Peer reviewedConsejo Superior de Investigaciones Científicas (España)A1 Solicitud de patente con informe sobre el estado de la técnic

Biosensor electrocrómico

[EN] The invention relates to a biosensor formed by an anode of a conductive material which contains at least one enzyme immobilised on the surface thereof and a redox mediator, and a cathode of a transparent material which contains an electrochromic molecule that changes colour when its state of oxidation changes. An ion-conductive medium in the form of a permeable membrane or gel is deposited between the anode and the cathode. This biosensor is activated automatically by the deposition of a sample containing an analyte generating an electron flow from the anode to the cathode by the enzymatic reduction/oxidation thereof, which causes the change in colour of the electrochromic material and provides immediate information to the user about the presence of said analyte in the sample.[ES] Biosensor electrocrómico. La presente invención se refiere a un biosensor formado por un ánodo de un material conductor que contiene al menos una enzima inmovilizada sobre su superficie y un mediador redox y un cátodo de un material transparente que contiene una molécula electrocrómica que cambia de color cuando cambia su estado de oxidación. Entre ánodo y cátodo se deposita un medio conductor de iones que puede estar en forma de gel o de membrana permeable. Este biosensor se activa automáticamente cuando se deposita una muestra que contenga el analito cuya oxidación/reducción enzimática genera un flujo de electrones desde el ánodo al cátodo que provoca el cambio de color del material electrocrómico y que da información inmediata al usuario de la presencia de dicho analito en la muestra.Peer reviewedConsejo Superior de Investigaciones Científicas (España)A1 Solicitud de patente con informe sobre el estado de la técnic

Electrochromic biosensor

[ES] Biosensor electrocrómico. La presente invención se refiere a un biosensor formado por un ánodo de un material conductor que contiene al menos una enzima inmovilizada sobre su superficie y un mediador redox y un cátodo de un material transparente que contiene una molécula electrocrómica que cambia de color cuando cambia su estado de oxidación. Entre ánodo y cátodo se deposita un medio conductor de iones que puede estar en forma de gel o de membrana permeable. Este biosensor se activa automáticamente cuando se deposita una muestra que contenga el analito cuya oxidación/reducción enzimática genera un flujo de electrones desde el ánodo al cátodo que provoca el cambio de color del material electrocrómico y que da información inmediata al usuario de la presencia de dicho analito en la muestra.[EN] The invention relates to a biosensor formed by an anode of a conductive material which contains at least one enzyme immobilised on the surface thereof and a redox mediator, and a cathode of a transparent material which contains an electrochromic molecule that changes colour when its state of oxidation changes. An ion-conductive medium in the form of a permeable membrane or gel is deposited between the anode and the cathode. This biosensor is activated automatically by the deposition of a sample containing an analyte generating an electron flow from the anode to the cathode by the enzymatic reduction/oxidation thereof, which causes the change in colour of the electrochromic material and provides immediate information to the user about the presence of said analyte in the sample.Peer reviewedConsejo Superior de Investigaciones Científicas (España)A1 Solicitud de patente con informe sobre el estado de la técnic

Electrochromic biosensor

[ES] Biosensor electrocrómico. La presente invención se refiere a un biosensor formado por un ánodo de un material conductor que contiene al menos una enzima inmovilizada sobre su superficie y un mediador redox y un cátodo de un material transparente que contiene una molécula electrocrómica que cambia de color cuando cambia su estado de oxidación. Entre ánodo y cátodo se deposita un medio conductor de iones que puede estar en forma de gel o de membrana permeable. Este biosensor se activa automáticamente cuando se deposita una muestra que contenga el analito cuya oxidación/reducción enzimática genera un flujo de electrones desde el ánodo al cátodo que provoca el cambio de color del material electrocrómico y que da información inmediata al usuario de la presencia de dicho analito en la muestra.[EN] The invention relates to a biosensor formed by an anode of a conductive material which contains at least one enzyme immobilised on the surface thereof and a redox mediator, and a cathode of a transparent material which contains an electrochromic molecule that changes colour when its state of oxidation changes. An ion-conductive medium in the form of a permeable membrane or gel is deposited between the anode and the cathode. This biosensor is activated automatically by the deposition of a sample containing an analyte generating an electron flow from the anode to the cathode by the enzymatic reduction/oxidation thereof, which causes the change in colour of the electrochromic material and provides immediate information to the user about the presence of said analyte in the sample.Peer reviewedConsejo Superior de Investigaciones Científicas (España)B1 Patente sin examen previ