This work is a part of the STW project "Integral solution for sustainable construction (IS2C, Fleur van Rossem for her support during the chip fabrication, Justyna Wiedemair for the chip design and Allison Bidulock for her support during the manuscript preparation.

1. fabricación de chips Nota: El chip consta de un electrodo Ag / AgCl de trabajo (WE), un electrodo de pseudo-referencia Ag / AgCl (pseudo-RE) y un contraelectrodo de platino en un chip de vidrio. El metal de plata se deposita en un chip de vidrio, utilizando procesos estándar de sala blanca 16. Se clorurada entonces en solución M FeCl 3 0,1 durante 30 s para formar una capa de AgCl sobre la superficie. El Ag / AgCl WE (área = 9,812 mm 2) está situado en el centro, rodeado por el Ag / AgCl pseudo-RE, como se muestra en la Figura 1. <ol><li> Depositar el metal de plata sobre el vidrio para formar un electrodo de plata planar. La fabricación de chips de paso a paso en una sala limpia se da como sigue: <ol><li> Litografía <ol><li> Para la limpieza de obleas, sumerja la oblea de vidrio por primera vez en conc. HNO 3 baño para eliminar cualquier contaminación orgánica y luego en 1 M de KOH para limpiar la superficie. </li><li> Aplicar una foto positiva resistir (200 nm de espesor) a laoblea mediante recubrimiento por rotación y de precocción la resisten a 95 ° C durante 15 min. </li><li> Exponer la oblea a la luz UV durante 5 segundos a través de una máscara de cristal. </li><li> Desarrollar la fotoprotección en la solución de revelado. Esto expondrá el área del vaso en el que se depositan los electrodos y el área restante será cubierto por los no expuestos resistir. </li></ol></li><li> grabado de vidrio <ol><li> Sumergir la oblea de vidrio desarrollado en el baño de KOH para grabar el área expuesta del vidrio. </li></ol></li><li> La deposición de metal (sputtering) <ol><li> Depósito de plata metálica sobre la superficie del cristal expuesto. <ol><li> En primer lugar una capa de depósito de 20 nm de titanio (Ti) (por pulverización catódica), como una capa de adhesión para el vidrio. </li><li> A continuación, depositar 70 nm de paladio (Pd) capa (por pulverización catódica) como barrera de difusión entre la plata y Ti. </li><li> Por último depósito de 500 nm de metal de plata. Este es el espesor del metal depositado. El área del electrodo de trabajo es de 4 mm 2. </li><li> Retire el remaining resistir por procedimiento de despegado en un baño de acetona. </li></ol></li><li> Se pica la oblea en el tamaño solo chip. El chip está ahora listo para ser clorurada para formar un electrodo de Ag / AgCl en el chip. </li></ol></li></ol></li><li> Colocar el chip en un soporte de chip de politetrafluoroetileno de diseño propio, como se muestra en la Figura 1. El titular proporciona conexiones eléctricas fáciles a través de los pasadores (o pasadores de resorte) y contiene una celda electroquímica. </li><li> Chloridize el electrodo de plata para formar un electrodo de Ag / AgCl en el chip. Para que, verter M FeCl solución 0,1 3 en la celda durante 30 s. o hasta que el color de la plata del electrodo se vuelve de color gris oscuro. la inmersión ya no es crítica mientras que un menor tiempo de inmersión puede dar lugar a ninguna deposición de Ag / AgCl. </li><li> Enjuague el chip con agua desionizada para limpiar el FeCl 3 de chip .El restante está ahora listo para ser utilizado para la medición chronopotentiometric. </li></ol>2. Preparación de electrolitos Nota: Los electrolitos se prepararon con diferentes concentraciones de cloruro de potasio en 0,5 M de KNO 3. <ol><li> Preparar 50 ml de KCl 50 mM solución de electrolito de stock (0,186 g de KCl en 50 ml de solución). </li><li> En la misma solución de añadir 2,52 g de KNO 3 para formar una 0,5 M KNO 3 de electrolito de fondo. </li><li> Mantener la concentración de partida de cloruro a cero y KNO 3 a 0,5 M. En otras palabras añadir 2,52 g de KNO 3 en unos 50 ml de agua desionizada. </li><li> Añadir KCl 50 mM para aumentar la concentración de iones cloruro (de 1 mM a 6 mM) del electrólito, de manera sistemática, tal como se muestra en los pasos siguientes. <ol><li> Añadir 100 l de KCl 50 mM en un 4,9 ml de 0,5 M de KNO 3 para obtener 1 mM [CL]. </li><li> Añadir 104 l de la solución 50 mM de KCl en la solución de la etapa 2.4.1 para obtener 2 mM [CL]. </li><li> Añadir 108.41 l de la solución 50 mM KCl en el slución de la etapa 2.4.2 para obtener 3 mM [CL]. </li><li> Añadir 113.19 l de la solución 50 mM de KCl en la solución de la etapa 2.4.3 para obtener 4 mM [CL]. </li><li> Añadir 118,2 l de la solución 50 mM de KCl en la solución de la etapa 2.4.4 para obtener 5 mM [CL]. </li><li> Añadir 123.3 l de la solución 50 mM de KCl en la solución de la etapa 2.4.5 para obtener 6 mM [CL]. </li></ol></li></ol> 3. Configuración Experimental Nota: Las mediciones se realizaron utilizando un potenciostato (biológica Ciencia Instrumentos, Francia). <ol><li> Colocar el chip en el soporte de chip y conectar el terminal correspondiente del potenciostato. </li><li> Conectar el terminal de electrodo de trabajo de la potenciostato al electrodo de Ag / AgCl. </li><li> Conectar el terminal de electrodo de referencia de la potenciostato a otro electrodo de Ag / AgCl. </li><li> Conectar el terminal de electrodo contador de la potenciostato para el electrodo de platino. </li><li> Coloque el borradorMontaje del ensayo lete en una jaula de Faraday para evitar el ruido ambiental. </li></ol> 4. Los ajustes de operación del instrumento Nota: Los parámetros de funcionamiento de la celda electroquímica se controlan a través de la interfaz de usuario del potenciostato. La respuesta potencial de la Ag / AgCl WE durante un impulso de corriente aplicada se mide de diferentes concentraciones de iones cloruro. <ol><li> En el programa potenciostato, abra la cronopotenciometría técnica y establecer los parámetros operativos. <ol><li> Establecer los siguientes parámetros de acuerdo con los requisitos: <ol><li> Corriente (I s) </li><li> Tiempo de corriente aplicada (t s) </li></ol></li><li> Comience esta técnica haciendo clic en el botón de reproducción en el programa potenciostato. Nota: El programa potenciostato muestra la respuesta potencial como una función del tiempo bajo el impulso de corriente aplicada. </li></ol></li></ol> 5. Mediciones y datos Analysis <ol><li> Dibujar la curva de calibración del tiempo de transición frente a la concentración de iones de Cl en el electrolito. <ol><li> Cambiar la concentración de Cl en el electrolito de KCl, de forma sistemática. <ol><li> Iniciar la medición con 5 ml de KCl 1 mM con 0,5 M de KNO3 electrolito de fondo en la celda electroquímica. </li><li> Iniciar el experimento chronopotentiometric utilizando el potenciostato y aplicar una corriente de 10 mA / cm-2 durante 10 segundos y almacenar los datos. </li><li> Sistemáticamente cambiar la concentración a 6 mm con incrementos de 1 mm y repetir las mediciones. </li></ol></li><li> Almacenar los datos medidos como a.mpt archivo y analizar el archivo de datos en el programa de procesamiento de datos. <ol><li> Analizar los datos usando un programa de procesamiento de datos desarrollado internamente para calcular la primera derivada de la posible respuesta y calcular el pico de la primera derivada. El pico de la primera derivada es el tiempo de transición. Nota: El bacalao completaING de programa de procesamiento de datos se dan en la información complementaria de Abbas et al., 2014. </li></ol></li><li> Repita la medición tres veces con el intervalo de 1 hr cada uno. </li><li> Abra todos los archivos de datos en el programa de procesamiento de datos y calcular el tiempo de transición para cada medición. Detalle pasos de cálculo del tiempo de transición es la siguiente: <ol><li> Trazar la diferencia de potencial en función del tiempo obtenido a partir de los archivos de datos de medición chronopotentiometric. </li><li> Calcular la primera derivada de la respuesta potencial. </li><li> Indicar el máximo de la primera derivada y el tiempo de la misma. El tiempo de la máxima de primera derivada es el tiempo de transición. </li></ol></li><li> Para la curva de calibración, trazar la raíz cuadrada del tiempo de transición con respecto a la concentración de iones Cl. </li><li> A lo largo de los datos medidos trazar la curva teórica sobre la base de la ecuación de arena 25. Calcular de nuevo la difusión Coefficient de la trama de datos. <ol><li> En la trama de datos, medida entre el tiempo de transición y el [CL] tomar cualquier punto de la línea y registrar el valor del tiempo de transición y el [CL]. La ecuación de la arena se da como: τ = (FC * / 2j (1-t Cl -)) 2 Dπ Aquí, C * es la concentración mayor de iones de Cl, F es la constante de Faraday, j es la densidad de corriente, t Cl - es el número de transporte y D es el coeficiente de difusión. Despreciar la t Cl - ya que se aproxima a cero para el fondo superior concentración de electrolito. </li><li> La variable que queda en la ecuación de la arena en el coeficiente de difusión; poner el valor del tiempo de transición, la concentración de iones cloruro y la corriente aplicada en la ecuación Sand obtener el valor del coeficiente de difusión. </li></ol></li></ol></li><li> Medición de deriva <ol><li> Verter 5 ml de 1 mM del KCl en lacelda electroquímica. </li><li> En el potenciostato, ajuste la corriente aplicada a las 10 horas y el tiempo de -2 a ser de 10 seg. </li><li> Medir la respuesta de potencial de 2 semanas con tres medición cada día con un intervalo de 3 horas entre las mediciones. </li><li> Actualizar el electrolito, es decir, mM KCl 1, cada día antes de realizar las mediciones. </li><li> Trazar el tiempo de transición de más de dos semanas de mediciones. El cambio en el tiempo de transición por día es la desviación de la respuesta tiempo de transición. </li></ol></li><li> Efecto del electrodo de pseudo-referencia en las mediciones de tiempo de transición Nota: Varios pseudo-referencias tales como un alambre de Ag / AgCl, un alambre de platino y un alambre de acero se prueban para medir el tiempo de transición. <ol><li> Verter 4 mM de KCl electrolito en la celda electroquímica. </li><li> Utilice Ag / AgCl como un electrodo de pseudo-referencia y conectarlo al terminal de electrodo de referencia del potenciostato. Debido al impulso de corriente anódica del Cl &amp; #713; iones se agotan cerca del electrodo de trabajo de Ag / AgCl. </li><li> Realice la medición chronopotentiometric aplicando una densidad de corriente de 15 Am -2 durante 10 s. </li><li> Repetir las mediciones con el platino como electrodo de pseudo-referencia y registrar los datos. </li><li> Repetir las mediciones con barra de acero como un electrodo de pseudo-referencia y registrar los datos. </li><li> Trazar el tiempo de transición medido para diversos electrodos de pseudo-referencia utilizados. </li><li> Repita el conjunto completo de medición con 5 mM de KCl y representar gráficamente el tiempo de transición usando varios electrodos de pseudo-referencia. </li></ol></li></ol>

<ol>
	<li>Page, C., Treadaway, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aspects+of+the+electrochemistry+of+steel+in+concrete.">Aspects of the electrochemistry of steel in concrete.</a> Nature. 297, 109-115 (1982).</li><li>Koleva, D. A., Hu, J., van Breugel, K., Boshkov, N., de Wit, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conventional+and+pulse+cathodic+protection+of+reinforced+concrete:+electrochemical+approach+and+microstructural+investigations.">Conventional and pulse cathodic protection of reinforced concrete: electrochemical approach and microstructural investigations.</a> ECS Transactions. 1, 287-298 (2006).</li><li>Montemor, M., Simoes, A., Ferreira, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chloride-induced+corrosion+on+reinforcing+steel:+from+the+fundamentals+to+the+monitoring+techniques.">Chloride-induced corrosion on reinforcing steel: from the fundamentals to the monitoring techniques.</a> Cement and Concrete Composites. 25, 491-502 (2003).</li><li>Wegen, G., Polder, R. B., Breugel, K. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Guideline+for+service+life+design+of+structural+concrete:+A+performance+based+approach+with+regard+to+chloride+induced+corrosion.">Guideline for service life design of structural concrete: A performance based approach with regard to chloride induced corrosion.</a> Heron. 57 (3), (2012).</li><li>Yoon, I., Koenders, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Theoretical+time+evolution+of+critical+chloride+content+in+concrete.">Theoretical time evolution of critical chloride content in concrete.</a> Structural Durability &amp; Health Monitoring. 5, 275-294 (2010).</li><li>Du, R. G., Hu, R. G., Huang, R. S., Lin, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+situ+measurement+of+Cl-concentrations+and+pH+at+the+reinforcing+steel/concrete+interface+by+combination+sensors.">In situ measurement of Cl-concentrations and pH at the reinforcing steel/concrete interface by combination sensors.</a> Analytical Chemistry. 78, 3179-3185 (2006).</li><li>Angst, U., Elsener, B., Larsen, C. K., Vennesland, &. #. 2. 1. 6. ;. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Potentiometric+determination+of+the+chloride+ion+activity+in+cement+based+materials.">Potentiometric determination of the chloride ion activity in cement based materials.</a> Journal of Applied Electrochemistry. 40, 561-573 (2010).</li><li>Laferri&#232;re, F., Inaudi, D., Kronenberg, P., Smith, I. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+system+for+early+chloride+detection+in+concrete.">A new system for early chloride detection in concrete.</a> Smart Materials and Structures. 17, 045017 (2008).</li><li>Tang, J. L., Wang, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+chloride-ion+concentration+with+long-period+grating+technology.">Measurement of chloride-ion concentration with long-period grating technology.</a> Smart Materials and Structures. 16, 665 (2007).</li><li>Kohri, M., Ueda, T., Mizuguchi, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+a+near-infrared+spectroscopic+technique+to+estimate+the+chloride+ion+content+in+mortar+deteriorated+by+chloride+attack+and+carbonation.">Application of a near-infrared spectroscopic technique to estimate the chloride ion content in mortar deteriorated by chloride attack and carbonation.</a> Journal of Advanced Concrete Technology. 8, 15-25 (2010).</li><li>Tripathi, S. R., Inoue, H., Hasegawa, T., Kawase, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-destructive+Inspection+of+Chloride+Ion+in+Concrete+Structures+Using+Attenuated+Total+Reflection+of+Millimeter+Waves.">Non-destructive Inspection of Chloride Ion in Concrete Structures Using Attenuated Total Reflection of Millimeter Waves.</a> Journal of Infrared, Millimeter, and Terahertz Waves. 34, 181-186 (2013).</li><li>Abbas, Y., Olthuis, W., van den Berg, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+chronopotentiometric+approach+for+measuring+chloride+ion+concentration.">A chronopotentiometric approach for measuring chloride ion concentration.</a> Sensors and Actuators B: Chemical. 188, 433-439 (2013).</li><li>Climent-Llorca, M. A., Viqueira-P&#233;rez, E., L&#242;pez-Atalaya, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Embeddable+Ag/AgCl+sensors+for+in-situ+monitoring+chloride+contents+in+concrete.">Embeddable Ag/AgCl sensors for in-situ monitoring chloride contents in concrete.</a> Cement and Concrete Research. 26, 1157-1161 (1996).</li><li>Myrdal, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The electrochemistry and characteristics of embeddable reference electrodes for concrete. , (2014).</li><li>Angst, U., Vennesland, &. #. 2. 1. 6. ;., Myrdal, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diffusion+potentials+as+source+of+error+in+electrochemical+measurements+in+concrete.">Diffusion potentials as source of error in electrochemical measurements in concrete.</a> Materials and Structures. 42, 365-375 (2009).</li><li>Abbas, Y., de Graaf, D. B., Olthuis, W., van den Berg, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=No+more+conventional+reference+electrode:+Transition+time+for+determining+chloride+ion+concentration.">No more conventional reference electrode: Transition time for determining chloride ion concentration.</a> Analytica Chimica Acta. 821, 81-88 (2014).</li><li>Meyer, R. E., Posey, F. A., Lantz, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chronopotentiometry+of+the+Ag&#8722;+AgCl+system+and+analysis+for+the+chloride+ion.">Chronopotentiometry of the Ag&#8722; AgCl system and analysis for the chloride ion.</a> Journal of Electroanalytical Chemistry and Interfacial Electrochemistry. 19, 99-109 (1968).</li><li>Olthuis, W., Langereis, G., Bergveld, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+metrits+of+differential+measuring+in+time+and+space.">The metrits of differential measuring in time and space.</a> Biocybernetics and Biomedical Engineering. 21, 5-26 (2001).</li><li>Bakker, E., Bhakthavatsalam, V., Gemene, K. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Beyond+potentiometry:+robust+electrochemical+ion+sensor+concepts+in+view+of+remote+chemical+sensing.">Beyond potentiometry: robust electrochemical ion sensor concepts in view of remote chemical sensing.</a> Talanta. 75, 629-635 (2008).</li><li>Olthuis, W., Bomer, J., Bergveld, P., Bos, M., Van der Linden, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Iridium+oxide+as+actuator+material+for+the+ISFET-based+sensor-actuator+system.">Iridium oxide as actuator material for the ISFET-based sensor-actuator system.</a> Sensors and Actuators B: Chemical. 5, 47-52 (1991).</li><li>Bergveld, P., Eijkel, J., Olthuis, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+protein+concentrations+with+chronopotentiometry.">Detection of protein concentrations with chronopotentiometry.</a> Biosensors and Bioelectronics. 12, 905-916 (1997).</li><li>Iwamoto, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Derivative+chronopotentiometry.">Derivative chronopotentiometry.</a> Analytical Chemistry. 31, 1062-1065 (1959).</li><li>Olthuis, W., Bergveld, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simplified+design+of+the+coulometric+sensor-actuator+system+by+the+application+of+a+time-dependent+actuator+current.">Simplified design of the coulometric sensor-actuator system by the application of a time-dependent actuator current.</a> Sensors and Actuators B: Chemical. 7, 479-483 (1992).</li><li>Olthuis, W., Bergveld, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integrated+coulometric+sensor-actuator+devices.">Integrated coulometric sensor-actuator devices.</a> Microchimica Acta. 121, 191-223 (1995).</li><li>Bard, A. J., Faulkner, L. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Electrochemical methods: fundamentals and applications. , (2001).</li><li>Bakker, E., B&#252;hlmann, P., Pretsch, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymer+Membrane+Ion-Selective+Electrodes-What+are+the+Limits?+.">Polymer Membrane Ion-Selective Electrodes-What are the Limits? .</a> Electroanalysis. 11, 915-933 (1999).</li></ol>

The authors have nothing to disclose.

El tiempo de transición es el momento de inflexión; teóricamente es independiente del potencial de referencia, es decir, el electrodo de referencia. Por tanto, cualquier alambre de metal se puede utilizar como un electrodo de pseudo-referencia para mediciones de tiempo de transición. En contraste con la medición potenciométrica existente de iones cloruro en el hormigón este método permite a un largo plazo y la calibración de medición libre. Además, la sensibilidad y el rango de detección de la conce...

Se presenta un sensor de iones de cloruro basado en la medición del tiempo de transición de un electrodo Ag / AgCl. El objetivo es evitar las derivas inherentes durante el seguimiento a largo plazo continuo de los iones cloruro en el electrolito. medición Chronopotentiometric, que es un método de medición dinámica, de un electrodo de Ag / AgCl se utiliza para este propósito. Aquí una tasa de cambio de potencial de un electrodo de Ag / AgCl se mide durante un estímulo (pulso galvanostático). La ventaja de este enfoque se demuestra por eludir el electrodo de referencia de unión líquida y en lugar de usar cualquier alambre de metal como un electrodo de pseudo-referencia, por lo tanto permitiendo la detección de Cl concentración iones de largo plazo (años) y en aplicaciones in situ, tales como medición en el interior de estructuras de hormigón. Los iones cloruro en las estructuras de hormigón es una de las principales causas de la degradación de 1,2. Inicia la corrosión por picadura en el refuerzo de acero de unaResultados de ND en el fracaso final de la estructura 3. Por lo tanto, la medición de iones de Cl en concreto es inevitable para predecir el ciclo de vida de servicio y mantenimiento de un 4,5 estructura. Diferentes principios de detección han sido reportados para la medición de iones cloruro en el hormigón como electroquímica 6,7, 8,9 y óptica electromagnética 10,11. Sin embargo, los métodos ópticos y electromagnéticos tienen configuraciones voluminosos, son difíciles de integrar como un sistema autónomo y tienen problemas con la selectividad 12. En técnica electroquímica, la medición potenciométrica de un electrodo Ag / AgCl es el estado de la 6,7,13 enfoque de la técnica. A pesar de los resultados prometedores, este enfoque se limita a la medición a escala de laboratorio desde las derivas en el potencial de referencia y los resultados de caída de potencial de difusión en datos defectuosos 14,15. Un enfoque tiempo de transición basado en la medición electroquímica dinámico (DEM) podría aliviar el problema debido al potencial16 la deriva. En el DEM, la respuesta de un sistema a un estímulo aplicado se mide 17-19. El ejemplo de tal sistema es cronopotenciometría. Aquí un impulso de corriente aplicada se utiliza como un estímulo ozono iones cerca de la superficie del electrodo y se mide la respuesta de potencial correspondiente. Una corriente anódica en un electrodo de Ag / AgCl inicia una reacción farádica (Ag + Cl <img alt="Figura 1" src="/files/ftp_upload/53312/arrow.jpg" /> AgCl + e) ​​lo que resulta en un agotamiento de los iones Cl cerca de la superficie del electrodo. El cambio de potencial es una función de la corriente aplicada y la concentración de los iones (selectivos) en el 12,20 electrolito. En el momento en que estos iones se agotan por completo cerca de la superficie del electrodo de la tasa de cambio de los potenciales aumentos rápidamente, dando un punto de inflexión 21. El punto de inflexión en la curva de respuesta en tiempo potencial (chronopotentiogram) muestra el tiempo de transición y puede determinarse a partir delmáximo de la primera derivada de la respuesta de potencial 22. El tiempo de transición es una característica de la concentración de iones. Este enfoque ha sido utilizado para determinar diferentes iones concentración 17 y el pH de electrolitos 23,24. En el caso de un electrodo de Ag / AgCl como un electrodo de trabajo (a la que se aplica corriente) los iones agotan serán iones cloruro 17. Por lo tanto, la medición de su tiempo de transición va a determinar su concentración.

<table border="0" cellpadding="0" cellspacing="0" width="1009">
	<tbody>
		<tr height="25">
			<td height="25" style="height:25px;width:373px;">Platinum wire (&#8805;99.99% trace metals)</td>
			<td style="width:292px;">Sigma Aldrich, the Netherlands</td>
			<td style="width:172px;">EP1330-1EA</td>
			<td style="width:172px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Potassium chloride (BioXtra, &#8805;99.0%)</td>
			<td>Sigma Aldrich, the Netherlands</td>
			<td>P9333-500G</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Potassium hydroxide (90% pure reagent grade)</td>
			<td>Sigma Aldrich, the Netherlands</td>
			<td>484016-1KG</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Ferric chloride&#160;</td>
			<td>Sigma Aldrich, the Netherlands</td>
			<td>451649-1G</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">potassium nitrate (&#62; 99% reagent grade)&#160;</td>
			<td>Sigma Aldrich, the Netherlands</td>
			<td>P6083-500G</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Ag/AgCl liquid junction reference electrode&#160;</td>
			<td>BASi, USA</td>
			<td>model MF-2079</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">VSP potentiostat</td>
			<td>Biologic Science Instruments, France</td>
			<td>VSP 300</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Steel wire</td>
			<td>Microlab TU Delft</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Silver wire&#160;</td>
			<td>Sigma Aldrich, the Netherlands</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

dynamic electrochemical measurement of chloride ions

This protocol describes the dynamic measurement of chloride ions using the transition time of a silver silver chloride (Ag/AgCl) electrode. Silver silver chloride electrode is used extensively for potentiometric measurement of chloride ions concentration in electrolyte. In this measurement, long-term and continuous monitoring is limited due to the inherent drift and the requirement of a stable reference electrode. We utilized the chronopotentiometric approach to minimize drift and avoid the use of a conventional reference electrode. A galvanostatic pulse is applied to an Ag/AgCl electrode which initiates a faradic reaction depleting the Cl&#713; ions near the electrode surface. The transition time, which is the time to completely deplete the ions near the electrode surface, is a function of the ion concentration, given by the Nernst equation. The square root of the transition time is in linear relation to the chloride ion concentration. Drift of the response over two weeks is negligible (59 &#181;M/day) when measuring 1 mM [Cl&#713;]using a current pulse of 10 Am-2. This is a dynamic measurement where the moment of transition time determines the response and thus is independent of the absolute potential. Any metal wire can be used as a pseudo-reference electrode, making this approach feasible for long-term measurement inside concrete structures.

El electrodo de Ag / AgCl se fabrica en un chip de vidrio (Figura 1) utilizando un proceso de sala limpia estándar. Se utilizó la configuración de la medición chronopotentiometric (Figura 2) y la respuesta se midió usando un potenciostato. Para observar el efecto de la concentración de iones de Cl en el tiempo de transición, las soluciones que contienen 4, 5 y 6 mM de Cl iones en un 0,5 M de KNO3 fondo se miden (Figura 3).</stro...

Watch this Scientific Journal Video about Dynamic Electrochemical Measurement of Chloride Ions at JoVE.com

Dynamic Electrochemical Measurement of Chloride Ions

Dynamic measurement of chloride ions is presented. Transition time of an Ag/AgCl electrode, during a chronopotentiometric technique, can give the concentration of chloride ions in electrolyte. This method does not require a stable conventional reference electrode.

Dinámica electroquímico Medición de cloruro de iones

This protocol describes the dynamic measurement of chloride ions using the transition time of a silver silver chloride (Ag/AgCl) electrode. Silver silver ...

dynamic-electrochemical-measurement-of-chloride-ions

Research

Education

JoVE Core

JoVE Journal

Analytical Chemistry

Chemistry

Unit 1

Electrochemical Analyses and Redox Titration

SCIENTISTS IN ACTION

11.3K vistas.  University of Twente. Dynamic measurement of chloride ions is presented. Transition time of an Ag/AgCl electrode, during a chronopotentiometric technique, can give the concentration of chloride ions in electrolyte. This method does not require a stable conventional reference electrode.

Video: Dynamic Electrochemical Measurement of Chloride Ions

Activating Molecules, Ions, and Solid Particles with Acoustic Cavitation

The chemical and physical effects of ultrasound arise not from a direct interaction of molecules with sound waves, but rather from the acoustic cavitation: the nucleation, growth, and implosive collapse of microbubbles in liquids submitted to power ultrasound. The violent implosion of bubbles leads to the formation of chemically reactive species and to the emission of light, named sonoluminescence. In this manuscript, we describe the techniques allowing study of extreme intrabubble conditions and chemical reactivity of acoustic cavitation in solutions. The analysis of sonoluminescence spectra of water sparged with noble gases provides evidence for nonequilibrium plasma formation. The photons and the "hot" particles generated by cavitation bubbles enable to excite the non-volatile species in solutions increasing their chemical reactivity. For example the mechanism of ultrabright sonoluminescence of uranyl ions in acidic solutions varies with uranium concentration: sonophotoluminescence dominates in diluted solutions, and collisional excitation contributes at higher uranium concentration. Secondary sonochemical products may arise from chemically active species that are formed inside the bubble, but then diffuse into the liquid phase and react with solution precursors to form a variety of products. For instance, the sonochemical reduction of Pt(IV) in pure water provides an innovative synthetic route for monodispersed nanoparticles of metallic platinum without any templates or capping agents. Many studies reveal the advantages of ultrasound to activate the divided solids. In general, the mechanical effects of ultrasound strongly contribute in heterogeneous systems in addition to chemical effects. In particular, the sonolysis of PuO2 powder in pure water yields stable colloids of plutonium due to both effects.

Acoustic cavitation in liquids submitted to power ultrasound creates transient extreme conditions inside the collapsing bubbles, which are the origin of unusual chemical reactivity and light emission, known as sonoluminescence. In the presence of noble gases, nonequilibrium plasma is formed. The "hot" particles and the photons generated by collapsing bubbles are able to excite species in solution.

Activación de moléculas, iones y partículas sólidas con cavitación acústica

The chemical and physical effects of ultrasound arise not from a direct interaction of molecules with sound waves, but rather from the acoustic ...

Investigación

Química

Measurement of Particle Size Distribution in Turbid Solutions by Dynamic Light Scattering Microscopy

A protocol for measuring polydispersity of concentrated polymer solutions using dynamic light scattering is described. Dynamic light scattering is a technique used to measure the size distribution of polymer solutions or colloidal particles. Although this technique is widely used for the assessment of polymer solutions, it is difficult to measure the particle size in concentrated solutions due to the multiple scattering effect or strong light absorption. Therefore, the concentrated solutions should be diluted before measurement. Implementation of the confocal optical component in a dynamic light scattering microscope1 helps to overcome this barrier. Using such a microscopic system, both transparent and turbid systems can be analyzed under the same experimental setup without a dilution. As a representative example, a size distribution measurement of a temperature-responsive polymer solution was performed. The sizes of the polymer chains in an aqueous solution were several tens of nanometers at a temperature below the lower critical solution temperature (LCST). In contrast, the sizes increased to more than 1.0 &#181;m when above the LCST. This result is consistent with the observation that the solution turned turbid above the LCST.

A protocol for the direct measurement of particle size distribution in concentrated solutions using dynamic light scattering microscopy is presented.

Medición de Tamaño de Partícula de distribución en turbias Soluciones por Dynamic Light Scattering Microscopía

A protocol for measuring polydispersity of concentrated polymer solutions using dynamic light scattering is described. Dynamic light scattering is a ...

Fabrication and Testing of Photonic Thermometers

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being leveraged for developing sophisticated photonic sensors. Silicon photonic sensors seek to exploit the strong confinement of light in nano-waveguides to transduce changes in physical state to changes in resonance frequency. In the case of thermometry, the thermo-optic coefficient, i.e., changes in refractive index due to temperature, causes the resonant frequency of the photonic device such as a Bragg grating to drift with temperature. We are developing a suite of photonic devices that leverage recent advances in telecom compatible light sources to fabricate cost-effective photonic temperature sensors, which can be deployed in a wide variety of settings ranging from controlled laboratory conditions, to the noisy environment of a factory floor or a residence. In this manuscript, we detail our protocol for the fabrication and testing of photonic thermometers.

We describe the process of fabrication and testing of photonic thermometers.

Fabricación y pruebas de termómetros fotónicos

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being ...

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

Espectroscopia de impedancia electroquímica como herramienta para la valoración constante de tipo electroquímico

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles

Bicyclic aziridinium ions were generated by the removal of an appropriate leaving group through internal nucleophilic attack by nitrogen atom in the aziridine ring. The utility of bicyclic aziridinium ions, specifically 1-azoniabicyclo[3.1.0]hexane and 1-azoniabicyclo[4.1.0]heptane tosylate highlighted in the aziridine ring openings by the nucleophile with the release of the ring strain to yield the corresponding ring-expanded azaheterocycles such as pyrrolidine, piperidine and azepane with diverse substituents on the ring in regio- and stereospecific manner. Herein, we report a simple and convenient method for the preparation of the stable 1-azabicyclo[4.1.0]heptane tosylate followed by selective ring opening via a nucleophilic attack either at the bridge or at the bridgehead carbon to yield piperidine and azepane rings, respectively. This synthetic strategy allowed us to prepare biologically active natural products containing piperidine and azepane motif including sedamine, allosedamine, fagomine and balanol in highly efficient manner.

Bicyclic aziridinium ions such as 1-azoniabicyclo[4.1.0]heptane tosylate were generated from 2-[4-tolenesulfonyloxybutyl]aziridine, which was utilized for the preparation of substituted piperidines and azepanes via regio- and stereospecific ring-expansion with various nucleophiles. This highly efficient protocol allowed us to prepare diverse azaheterocycles including natural products such as fagomine, febrifugine analogue and balanol.

Preparación de iones Aziridinium bicíclica estable y su apertura para la síntesis de Azaheterocycles

Bicyclic aziridinium ions were generated by the removal of an appropriate leaving group through internal nucleophilic attack by nitrogen atom in the ...

Disentangling High Strength Copolymer Aramid Fibers to Enable the Determination of Their Mechanical Properties

Traditionally, soft body armor has been made from poly(p-phenylene terephthalamide) (PPTA) and ultra-high molecular weight polyethylene. However, to diversify the fiber choices in the United States body armor market, copolymer fibers based on the combination of 5-amino-2-(p-aminophenyl) benzimidazole (PBIA) and the more conventional PPTA were introduced. Little is known regarding the long-term stability of these fibers, but as condensation polymers, they are expected to have potential sensitivity to moisture and humidity. Therefore, characterizing the strength of the materials and understanding their vulnerability to environmental conditions is important for evaluating their use lifetime in safety applications. Ballistic resistance and other critical structural properties of these fibers are predicated on their strength. To accurately determine the strength of the individual fibers, it is necessary to disentangle them from the yarn without introducing any damage. Three aramid-based copolymer fibers were selected for the study. The fibers were washed with acetone followed by methanol to remove an organic coating that held the individual fibers in each yarn bundle together. This coating makes it difficult to separate single fibers from the yarn bundle for mechanical testing without damaging the fibers and affecting their strength. After washing, fourier transform infrared (FTIR) spectroscopy was performed on both washed and unwashed samples and the results were compared. This experiment has shown that there are no significant variations in the spectra of poly(p-phenylene-benzimidazole-terephthalamide-co-p-phenylene terephthalamide) (PBIA-co-PPTA1) and PBIA-co-PPTA3 after washing, and only a small variation in intensity for PBIA. This indicates that the acetone and methanol rinses are not adversely affecting the fibers and causing chemical degradation. Additionally, single fiber tensile testing was performed on the washed fibers to characterize their initial tensile strength and strain to failure, and compare those to other reported values. Iterative procedural development was necessary to find a successful method for performing tensile testing on these fibers.

The primary goal of the study is to develop a protocol to prepare consistent specimens for accurate mechanical testing of high strength copolymer aramid fibers, by removing a coating and disentangling the individual fiber strands without introducing significant chemical or physical degradation.

Desenredar las fibras de aramida de copolímero de alta resistencia para permitir la determinación de sus propiedades mecánicas

Traditionally, soft body armor has been made from poly(p-phenylene terephthalamide) (PPTA) and ultra-high molecular weight polyethylene. However, to ...

Electrochemical Roughening of Thin-Film Platinum Macro and Microelectrodes

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries of the metal. Using this method, a crack free, thin-film macroelectrode surface with up to 40 times increase in active surface area was obtained. The roughening is easy to do in a standard electrochemical characterization laboratory and incudes the application of voltage pulses followed by extended application of a reductive voltage in a perchloric acid solution. The protocol includes the chemical and electrochemical preparation of both a macroscale (1.2 mm diameter) and microscale (20 &#181;m diameter) platinum disc electrode surface, roughening the electrode surface and characterizing the effects of surface roughening on electrode active surface area. This electrochemical characterization includes cyclic voltammetry and impedance spectroscopy and is demonstrated for both the macroelectrodes and the microelectrodes. Roughening increases electrode active surface area, decreases electrode impedance, increases platinum charge injection limits to those of titanium nitride electrodes of same geometry and improves substrates for adhesion of electrochemically deposited films.

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries. The electrochemical techniques of cyclic voltammetry and impedance spectroscopy are demonstrated to characterize these electrode surfaces.

Desbaste electroquímico de macro y microelectrodos de platino de película delgada

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries ...

Asymmetric Thermoelectrochemical Cell for Harvesting Low-grade Heat under Isothermal Operation

Low-grade heat is abundantly available in the environment as waste heat. The efficient conversion of low-grade heat into electricity is very difficult. We developed an asymmetric thermoelectrochemical cell (aTEC) for heat-to-electricity conversion under isothermal operation in the charging and discharging processes without exploiting the thermal gradient or the thermal cycle. The aTEC is composed of a graphene oxide (GO) cathode, a polyaniline (PANI) anode, and 1M KCl as the electrolyte. The cell generates a voltage due to the pseudocapacitive reaction of GO when heating from room temperature (RT) to a high temperature (TH, ~40-90 &#176;C), and then current is successively produced by oxidizing PANI when an external electrical load is connected. The aTEC demonstrates a remarkable temperature coefficient of 4.1 mV/K and a high heat-to-electricity conversion efficiency of 3.32%, working at a TH = 70 &#176;C with a Carnot efficiency of 25.3%, unveiling a new promising thermoelectrochemical technology for low-grade heat recovery.

Low-grade heat is abundant, but its efficient recovery is still a great challenge. We report an asymmetric thermoelectrochemical cell using graphene oxide as a cathode and polyaniline as an anode with KCl as the electrolyte. This cell works under isothermal heating, exhibiting a high heat-to-electricity conversion efficiency in low-temperature regions.

Célula termoelectroquímica asimétrica para la cosecha de calor de bajo grado bajo operación isotérmica

Low-grade heat is abundantly available in the environment as waste heat. The efficient conversion of low-grade heat into electricity is very difficult. We ...

Fabrication of Thin Film Silver/Silver Chloride Electrodes with Finely Controlled Single Layer Silver Chloride

This paper aims to present a protocol to form smooth and well-controlled films of silver/silver chloride (Ag/AgCl) with designated coverage on top of thin film silver electrodes. Thin film silver electrodes sized 80 &#181;m x 80 &#181;m and 160 &#181;m x 160 &#181;m were sputtered on quartz wafers with a chromium/gold (Cr/Au) layer for adhesion. After passivation, polishing and cathodic cleaning processes, the electrodes underwent galvanostatic oxidation with consideration of Faraday&#39;s Law of Electrolysis to form smooth layers of AgCl with a designated degree of coverage on top of the silver electrode. This protocol is validated by inspection of scanning electron microscope (SEM) images of the surface of the fabricated Ag/AgCl thin film electrodes, which highlights the functionality and performance of the protocol. Sub-optimally fabricated electrodes are fabricated as well for comparison. This protocol can be widely used to fabricate Ag/AgCl electrodes with specific impedance requirements (e.g., probing electrodes for impedance sensing applications like impedance flow cytometry and interdigitated electrode arrays).

This paper aims to present a method to form smooth and well-controlled films of silver chloride (AgCl) with designated coverage on top of thin film silver electrodes.

Fabricación de electrodos de cloruro de plata/plata de película delgada con cloruro de plata de una sola capa finamente controlado

This paper aims to present a protocol to form smooth and well-controlled films of silver/silver chloride (Ag/AgCl) with designated coverage on top of thin ...

Probing Surface Electrochemical Activity of Nanomaterials using a Hybrid Atomic Force Microscope-Scanning Electrochemical Microscope (AFM-SECM)

Scanning electrochemical microscopy (SECM) is used to measure the local electrochemical behavior of liquid/solid, liquid/gas and liquid/liquid interfaces. Atomic force microscopy (AFM) is a versatile tool to characterize micro- and nanostructure in terms of topography and mechanical properties. However, conventional SECM or AFM provides limited laterally resolved information on electrical or electrochemical properties at nanoscale. For instance, the activity of a nanomaterial surface at crystal facet levels is difficult to resolve by conventional electrochemistry methods. This paper reports the application of a combination of AFM and SECM, namely, AFM-SECM, to probe nanoscale surface electrochemical activity while acquiring high-resolution topographical data. Such measurements are critical to understanding the relationship between nanostructure and reaction activity, which is relevant to a wide range of applications in material science, life science and chemical processes. The versatility of the combined AFM-SECM is demonstrated by mapping topographical and electrochemical properties of faceted nanoparticles (NPs) and nanobubbles (NBs), respectively. Compared to previously reported SECM imaging of nanostructures, this AFM-SECM enables quantitative assessment of local surface activity or reactivity with higher resolution of surface mapping.

Probing Surface Electrochemical Activity of Nanomaterials using a Hybrid Atomic Force Microscope-Scanning Electrochemical Microscope AFM-SECM

Atomic force microscopy (AFM) combined with scanning electrochemical microscopy (SECM), namely, AFM-SECM, can be used to simultaneously acquire high-resolution topographical and electrochemical information on material surfaces at nanoscale. Such information is critical to understanding heterogeneous properties (e.g., reactivity, defects, and reaction sites) on local surfaces of nanomaterials, electrodes and biomaterials.

Sondeo de la superficie de la actividad electroquímica de los nanomateriales utilizando un microscopio híbrido de barrido de fuerza atómica-microscopio electroquímico (AFM-SECM)

Scanning electrochemical microscopy (SECM) is used to measure the local electrochemical behavior of liquid/solid, liquid/gas and liquid/liquid interfaces. ...