The development of a thick-film electrochemical sensor andinstrumentation for in-situ determination of carbon dioxide partialpressure (pCO₂) in the marine environment

摘要

Describes the development of a fast-response amperometric sensorfor recording in-situ measurements of carbon dioxide partial pressure(pCO₂) in the oceans. Carbon dioxide diffuses through amembrane, lowering the pH of the internal electrolyte. This causes ametal complex to dissociate; the increase in uncomplexed metal ion isdetected by voltammetry. The innovation in this design is achieved byprinting polymeric thick film electrodes (Au, Pt, Ag/AgCl) onto poroussubstrates. Careful design to minimize iR drop and electrode capacitanceallows transient voltammetric techniques to be used (scan rates up to 1V/s), whilst still keeping the working electrode close to the membraneto ensure a fast response, thereby giving improved sensitivity andprecision over conventional amperometric sensors. Analogue electronicsare combined with microcontroller-based digital signal processing toincrease the signal-to-noise ratio. Data can be processed and stored inthe microcontroller's memory, allowing the instrument to be deployedremotely (for example on databuoys or underwater vehicles)