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Silicon nitride photonics is on the rise owing to the broadband nature of the material, allowing applications of biophotonics, tele/datacom, optical signal processing and sensing, from visible, through near to mid-infrared wavelengths. In this paper, a review of the state of the art of silicon nitride strip waveguide platforms is provided, alongside the experimental results on the development of a versatile 300 nm guiding film height silicon nitride platform.

Microband electrode arrays are useful tools for the electrochemist, offering the enhanced sensitivity associated with microelectrodes but with a higher total current output. For optimum performance, the array may be designed such that space is used efficiently but the individual microbands behave as isolated electrodes on the time scale of the experiment. For a linear sweep experiment, the optimum specifications of a microband array depend on the scan rate used and the diffusion coefficient of the electroactive species. A two-dimensional simulation method is used to examine the nature of the diffusion to a regular array of microbands. Cyclic voltammetry of hexaammineruthenium(III)chloride is performed at a regularly spaced microband array to test the theory.

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Arrays of microdisc electrodes have found widespread use in electroanalysis. These are commonly produced lithographically and practical arrays may contain up to hundreds of individual disc electrodes (e.g. of gold, platinum, indium,...) to maximise sensitivity and minimise limits of detection. Typically, however, the lithographic fabrication process is imperfect resulting in a significant fraction (often tens of percent) of electrochemically inactive electrodes. We demonstrate that a 2-dimensional simulation based on the diffusion domain approximation in conjugation with simple experiments on the ferrocyanide redox couple in aqueous solutions can be used to rigorously 'count' the number of active electrodes in a non-destructive fashion. The agreement with an independent count in which active electrodes are identified via electro-plating with copper followed by ex situ microscopic examination is quantitatively excellent.

A regular array of identically sized microdroplets of 2.5 μm radius of the water-insoluble liquid N,N-didodecyl-N‘,N‘-diethylphenylenediamine (DDPD) is immobilized on the nonconducting hydrophobic polymer blocks of a gold partially blocked electrode. Cyclic voltammetric and chronoamperometric measurements for the oxidation of the DDPD microdroplets immersed in an aqueous solution are then recorded for different electrolytes (NaClO4, NaCl, NaBr, NaNO3, Na2SO4, and NaF). Specifically, the cyclic-voltammetric measurements allow us for the first time ever to observe a pre-peak, which can be interpreted as the movement of charge across the surface of the hemispherical droplets before the bulk material of the droplets gets oxidized. Conversion of the whole bulk material in all droplets is obtained by chronoamperometry. The resulting current−time responses show Cottrellian diffusion at sufficiently short times and are modeled by simulating diffusion through the droplet revealing complex behavior, which is likely to be related to anion dehydration and/or tight and weak ion-pair formation.

This work demonstrates the continuous detection of hypochlorite in tap water using bare platinum electrodes. Continuous amperometric operation is possible for several days in spite of Pt oxide formation. Pt oxides are formed both by simple contact of the Pt surface with a hypochlorite solution, and during the electrochemical reduction of hypochlorite ions. Pt oxide and hypochlorite reduction processes may overlap at moderate to high hypochlorite concentrations, resulting in erroneous concentration readings. Passivated cathodes are reactivated by cathodic cycling in supporting electrolyte. Electrode protection using suitable membranes may extend the useful life time of Pt electrodes, particularly in complex samples.