ELECTROCHEMICAL ENGINEERING The research performed in this group represents applications of electrochemical engineering to systems of practical importance. In recent work, electrokinetic phenomena were exploited to enhance continuous separation of water from dilute suspensions of clay associated with phosphate mining operations. The technology developed in this project is intended to greatly reduce the environmental impact of mining operations. Our group recently patented a sensor, based on indirect impedance measurements, that can detect corrosion of post-tensioned tendons in segmentally constructed bridges.

ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY Electrochemical impedance spectroscopy is an experimental technique in which sinusoidal modulation of an input signal is used to obtain the transfer function for an electrochemical system. In its usual application, the modulated input is potential, the measured response is current, and the transfer function is represented as an impedance. The impedance is obtained at different modulation frequencies, thus invoking the term spectroscopy. Through use of system-specific models, the impedance response can be interpreted in terms of kinetic and transport parameters. Through an international collaboration with scientists and engineers from France, Italy, and the United States, work is underway to improve the understanding of how impedance can be interpreted to gain insight into the physics and chemistry of such diverse systems as batteries, fuel cells, corroding metals, and human skin.

Current projects include a modelling and experimental study of the impedance of enzyme-based sensors for biological systems, use of impedance spectroscopy to explore the failure mechanisms for quantum-dot light-emitting diodes, and fundamental studies designed to enhance interpretation of impedance spectra. For example, in collaboration with French and Italian colleagues, our group developed a novel method to extract physically meaningful information from impedance data affected by frequency dispersion, a problem that had been unresolved since it was identified in the 1940s. Our power-law model, first published in 2010, has proven useful for oxides on metals, for human skin, and for water uptake in coatings. It is Now implemented in industry to assess the quality of raw materials for electrochemical fabrication lines. Our new understanding of the influence of electrode geometry on impedance response gives developers of impedance-based sensors guidelines for electrode size and shape.