Advances in electroanalysis, sensing and monitoring in molten salts

Abstract

Microelectrodes have a number of advantages over macroelectrodes for quantitative electroanalysis and monitoring, including reduced iR drop, a high signal-to-noise ratio and reduced sensitivity to convection. Their use in molten salts has been generally precluded by the combined materials challenges of stresses associated with thermal cycling and physical and corrosive chemical degradation at the relatively high temperatures involved. We have shown that microfabrication, employing high precision photolithographic patterning in combination with the controlled deposition of materials, can be used to successfully address these challenges. The resulting molten salt compatible microelectrodes (MSMs) enable prolonged quantitative microelectrode measurements in molten salts (MSs). This paper reports the fabrication of novel MSM disc electrodes, chosen because they have an established ambient analytical response. It includes a detailed set of electrochemical characterisation studies which demonstrate both their enhanced capability over macroelectrodes and over commercial glass pulled microelectrodes, and their ability to extract quantitative electroanalytical information from MS systems. MSM measurements are then used to demonstrate their potential for shedding new light on the fundamental properties of, and processes in, MSs, such as mass transport, charge transfer reaction rates and the selective plating/stripping and alloying reactions of liquid Bi and other metals; this will underpin the development of enhanced MS industrial processes, including pyrochemical spent nuclear fuel reprocessing.

A Microelectrode Array with Reproducible Performance Shows Loss of Consistency Following Functionalization with a Self-Assembled 6-Mercapto-1-hexanol Layer

“…In the manufacture of microelectrode systems capable of sensing multiple analytes on a single device, photolithographic microfabrication techniques from the silicon integrated circuit industry are particularly attractive due to the ability to fabricate precise and reproducible structures of known shape and dimension [ 14 ]. Recent studies have demonstrated the successful fabrication of devices using such methods and the subsequent electrochemical measurements on electrodes of controlled shape and dimensions [ 15 , 16 , 17 ]. In addition, recent work has systematically investigated the combinations of device layers and materials to achieve optimal electrochemical responses and durability [ 18 ].…”

Impedimetric measurement of DNA–DNA hybridisation using microelectrodes with different radii for detection of methicillin resistant Staphylococcus aureus (MRSA)

“…They offer a number of advantages over macroelectrodes for electrochemical sensing 5 in chemical 3 , industrial 6,7 and medical applications 8 . These advantages make microelectrodes and arrays of microelectrodes an attractive technology for sensitive and specific detection of biomarkers.…”

Improving the Yield and Lifetime of Microfabricated Sensors for Harsh Environments

“…This estimate identified that 75% of the current leakages were in a range of 10 A to 1 nA. These current levels are in the range of the currents recorded in electrochemical measurements with microelectrodes [7]- [9]. This means identifying small leakage currents when using microelectrodes is difficult in the majority of cases.…”

“…These microelectrodes had a yield of only 45.8% (n = 84) when operated in the LKE. Functioning microelectrodes demonstrated quantifiable steady-state currents of around 50 -500 nA depending on the microelectrode size [7], [9]. The majority of failed IMLs exhibited high currents of the order of 1 -10 A and no steady-state current.…”