Cutting-edge technologies for the design of electrochemical sensors

Emerging of new generation of chemical pollutants and the need to perform rapid and easy-to-make analysis for healthcare purpose, has requested the application of new technologies for the development of high performance, small-sized portable easy-to-make sensing platforms. Currently, the recent improvement in the electronics industry, the availability of advanced fabrication technologies down to the micro and nanoscale, and the application of last discovered smart nanomaterials has boosted the possibility to deliver a new generation of sensing tools. Among several analytical techniques, electrochemical ones can be highly improved by the use of these new technologies in terms of sensitivity and selectivity. Indeed miniaturisation of electronic components, new approaches based on the use of smart nano-structured materials, and printing technologies able to fabricate small dimension electrodes, can enhance the performances of electrochemical sensors, delivering sensing platforms with lower fabrication costs, short-time response, minimal volume requirement and small-sized, with the possibility to be applied for in-situ analysis. In this scenario, a first research work during my PhD period was focused on the study and characterisation of a carbon-based nanomaterial, namely Carbon Black. In detail, the properties of several types of Carbon Black were investigated by means of morphological study, i.e. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), and structural analysis, i.e. Raman spectroscopy. Furthermore, an electrochemical characterization was performed by cyclic voltammetry, electrochemical impedance spectroscopy and amperometry to deeply investigate application of Carbon Black as nanomodifier to enhance the performances of screen-printed electrodes. In addition, Carbon Black N220 was employed to modify electrodes screen-printed onto several environmental-friendly paper-based substrate, including paper towel, waxed paper and Parafilm M®. A morphological characterisation was performed on the bare sensors printed onto these unusual paper-based substrates. Afterward, the electrochemical performances of the implemented carbon black modified electrodes were evaluated, revealing their enhanced analytical capability, compared to the bare ones. A second part of the work has concerned the development of a high portable and easy-to-use electrochemical sensing platform called “lab-on-a-tip”: the whole electrochemical cell, i.e. wire electrodes, and a cotton wool filter were introduced into a customized pipette tip, allowing for the fabrication of a user-friendly and cost-effective sensing tool. As proof of concept of the novel approach, copper ions were detected in water sample by means of anodic stripping voltammetry. Finally, an integrated potentiometric wearable sensor was developed to monitoring pH in sweat sample during running activity, for its application in biomedical field. In detail, the sensor exploits an iridium oxide electrodeposited layer as sensitive material to H+ ions activity, performing a potentiometric measurement of the sample. The two-electrode system, i.e. a graphite working and an Ag/AgCl reference electrode were screen-printed onto a Kapton substrate, and embedded on the same substrate with a small-sized and low energy consumption circuit board, allowing for data acquisition and wireless transmitting during a physical activity. In vivo measurements were performed on a runner subject, highlighting the application for real-time on-body analysis.