A wireless potentiostat for mobile chemical sensing and biosensing.

Wireless chemical sensors are used as analytical devices in homeland defence, home-based healthcare, food logistics and more generally for the Sensor Internet of Things (SIoT). Presented here is a battery-powered and highly portable credit-card size potentiostat that is suitable for performing mobile and wearable amperometric electrochemical measurements with seamless wireless data transfer to mobile computing devices. The mobile electrochemical analytical system has been evaluated in the laboratory with a model redox system - the reduction of hexacyanoferrate(III) - and also with commercially available enzymatic blood-glucose test-strips. The potentiostat communicates wirelessly with mobile devices such as tablets or Smartphones by near-field communication (NFC) or with personal computers by radio-frequency identification (RFID), and thus provides a solution to the 'missing link' in connectivity that often exists between low-cost mobile and wearable chemical sensors and ubiquitous mobile computing products. The mobile potentiostat has been evaluated in the laboratory with a set of proof-of-concept experiments, and its analytical performance compared with a commercial laboratory potentiostat (R(2)=0.9999). These first experimental results demonstrate the functionality of the wireless potentiostat and suggest that the device could be suitable for wearable and point-of-sample analytical measurements. We conclude that the wireless potentiostat could contribute significantly to the advancement of mobile chemical sensor research and adoption, in particular for wearable sensors in healthcare and sport physiology, for wound monitoring and in mobile point-of-sample diagnostics as well as more generally as a part of the Sensor Internet of Things.

A novel biamperometric biosensor for urinary oxalate determination using flow-injection analysis.

A biosensor for determination of oxalate concentration in urine has been developed by immobilisation of oxalate oxidase and peroxidase on the surface of an interdigitated gold electrode. Enzyme immobilisation was performed using BSA and glutaraldehyde. Biamperometric measurements were made in flow conditions both in aqueous oxalate solutions (tested concentration range between 50 microM and 10 mM) and in real urine samples (tested measuring range between 5 and 100 microM). Optimal working conditions were examined for flow-injection analysis, and good correlation was achieved between added oxalate quantity and the one measured by biosensor in urine matrix (R(2)=0.9983). The influence of some interferences (ascorbic acid, uric acid, paracetamol, acetylsalicylic acid) was also studied using biamperometric measurement mode.

A novel method for flow injection analysis of total antioxidant capacity using enzymatically produced ABTS*+ and biamperometric detector containing interdigitated electrode.

Application of interdigitated array microelectrodes as electrochemical sensors for determination of antioxidant capacity is reported. Electrochemical measurements with interdigitated electrodes (IDE) were studied in both stationary solutions and the flow system. The method is based on biamperometric measurements using ABTS(*+)|ABTS redox couple in phosphate buffer solution, pH 7.40. During analysis, the ABTS radical cation was enzymatically produced by peroxidase in a tubular flow-through reactor. The performance of bioreactor was tested at different concentrations of immobilized enzyme, ABTS and hydrogen peroxide. The influence of flow rate on proper operation of the bioreactor was also studied. The results of antioxidant activity were determined using Trolox as a standard. The applied IDE detector accomplished good sensitivity of 0.3nA/microM of Trolox and offered linear range between 20 to 500microM of Trolox. The comparison of results (R(2)=0.9915) for antioxidant activity between spectroscopic and FIA biamperometric measurements by interdigitated electrodes confirmed the applicability of the proposed method for determination of antioxidant capacity.