Tea-waste biochar produced under different pyrolysis temperatures were subjected to three acid modifications and a comparative evaluation of their key physicochemical characteristics made.

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A high-performance, economical, disposable and flexible impedimetric humidity sensor was developed using polyaniline, paper substrate and three-electrode configuration.

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A paper-based microfluidic device with Agaricus bisporus homogenate as the working electrode modifier was developed based on cyclic voltammetry for quantitative detection of ethanol in biological samples. Mushroom homogenate was mixed with gelatin and combined with carbon paste to prepare a slurry to develop the working electrode on paper. The homogenate contained alcohol oxidase enzyme that catalyzed the degradation of ethanol to acetaldehyde and hydrogen peroxide in the presence of oxygen. A graphite crystalline pencil (5HB) was used to draw the counter electrode and a silver conductive ink pen was used to draw the reference electrode on the paper. Assay is based on the detection of reduction peaks of remaining oxygen at the working electrode using cyclic voltammetry at potentials between +0.4 and +0.8 V. The expected electrode response showed a linier relationship for ethanol concentrations ranging from 4.0 to 14.0 mM. Phosphate buffer (pH = 7) was used as the supporting electrolyte and it also provided the optimal condition for the activity of alcohol oxidase enzyme extracted from the mushroom tissue. The proposed paper-based device was validated using laboratory prepared samples.