title: Sensor-actuator system for dynamic chloride ion determination.
abstract: Chloride is a crucial anion for various analytical applications from biological to environmental applications. In order to measure the chloride ion concentration, a measurement system is needed which can detect this concentration for prolonged times reliably. Chronopotentiometry is a technique which does not need a long term stable reference electrode and is therefore very suitable for prolonged ion concentration measurements. As the used electrode might be fouled by reaction products, this work focuses on a chronopotentiometric approach with a separated sensing electrode (sensor) and actuating electrode (actuator). Both actuation and sensor electrode are made of Ag/AgCl. A constant current is applied to the actuator and will start the reaction between Ag and Cl-, while the resulting Cl- ion concentration change is observed through the sensor, which is placed close to the actuator. The time it takes to locally deplete the Cl- ions is called transition time. Experiments were performed to verify the feasibility of this approach. The performed experiments show that the sensor detects the local concentration changes resulting from the current applied to the actuator. A linear relation between the Cl- ion concentration and the square root of the transition time was observed, just as was predicted by theory. The calibration curves for different chips showed that both a larger sensor and a larger distance between sensor and actuator resulted in a larger time delay between the transition time detected at the actuator and the sensor.
authors: BIOS-Lab on a Chip Group, MESA+ Institute for Nanotechnology, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, 7500AE Enschede, The Netherlands.
authors: Derk Balthazar
authors: DB
authors: de Graaf
authors: BIOS-Lab on a Chip Group, MESA+ Institute for Nanotechnology, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, 7500AE Enschede, The Netherlands. Electronic address: y.abbas@utwente.nl.
authors: Yawar
authors: Y
authors: Abbas
authors: BIOS-Lab on a Chip Group, MESA+ Institute for Nanotechnology, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, 7500AE Enschede, The Netherlands.
authors: Johan
authors: J
authors: Gerrit Bomer
authors: BIOS-Lab on a Chip Group, MESA+ Institute for Nanotechnology, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, 7500AE Enschede, The Netherlands.
authors: Wouter
authors: W
authors: Olthuis
authors: BIOS-Lab on a Chip Group, MESA+ Institute for Nanotechnology, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, 7500AE Enschede, The Netherlands.
authors: Albert
authors: A
authors: van den Berg
mesh_terms: D002712:Chlorides / Q000032:analysis*; D004566:Electrodes; D004867:Equipment Design; D011199:Potentiometry / Q000295:instrumentation*; D012834:Silver / Q000737:chemistry; D018030:Silver Compounds / Q000737:chemistry
chemical_list: D002712:Chlorides; D018030:Silver Compounds; D012834:Silver; C037548:silver chloride
keywords: Chloride ion measurement; Chronopotentiometry; Pseudo-reference electrode; Separated sensor–actuator; Silver/silver chloride electrode; Transition time