Electrochromic materials can be used in self-powered electrochemical sensors to display quantitative information without the need for silicon-based electronics or external instrumentation.

The effect of changing the distance of an ultrasonic horn tip from a stationary platinum disk electrode on limiting current density at various electroanalyte concentrations, ultrasonic frequencies (20 and <mml:math display="inline"><mml:mrow><mml:mn>40</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mi>kHz</mml:mi></mml:mrow></mml:math>40kHz ), and ultrasonic intensities was studied in an attempt to find the optimum position required for maximum sonoelectrochemical effect in “face-on” mode. Our findings were compared to mathematical models available in the literature, for the mass transport of electroactive species to the electrode under hydrodynamic flow conditions normal to the ultrasonic horn. A good fit with experimental results was found and confirmed the dependence of limiting current to operating parameters such as ultrasonic power, electrode-to-horn distances and electroactive species diffusion coefficient, and also highlighting the importance of ultrasonic frequency. From mass balance equations, it was then possible to develop an approach by analogy to an electrode subjected to pure hydrodynamic flow. A Levich-like equation relating the limiting current density, the square root of ultrasonic intensity, and the inverse square root of the electrode-horn distance was generated for ultrasonic frequencies of 20 and <mml:math display="inline"><mml:mrow><mml:mn>40</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mi>kHz</mml:mi></mml:mrow></mml:math>40kHz , allowing the generation of an “equivalent” flow velocity under sonication, an important and useful parameter in chemical engineering.

Bio-composite coatings consisting of poly(3,4-ethylenedioxythiophene) (PEDOT) and tyrosinase (Ty) were successfully electrodeposited on conventional size gold (Au) disk electrodes and microelectrode arrays using sinusoidal voltages. Electrochemical polymerization of the corresponding monomer was carried out in the presence of various Ty amounts in aqueous buffered solutions. The bio-composite coatings prepared using sinusoidal voltages and potentiostatic electrodeposition methods were compared in terms of morphology, electrochemical properties, and biocatalytic activity towards various analytes. The amperometric biosensors were tested in dopamine (DA) and catechol (CT) electroanalysis in aqueous buffered solutions. The analytical performance of the developed biosensors was investigated in terms of linear response range, detection limit, sensitivity, and repeatability. A semi-quantitative multi-analyte procedure for simultaneous determination of DA and CT was developed. The amperometric biosensor prepared using sinusoidal voltages showed much better analytical performance. The Au disk biosensor obtained by 50 mV alternating voltage amplitude displayed a linear response for DA concentrations ranging from 10 to 300 μM, with a detection limit of 4.18 μM.