A novel, highly sensitive and selective safrole sensor has been developed using quartz crystal microbalance (QCM) coated with polyvinyl acetate (PVAc) nanofibers. The nanofibers were collected on the QCM sensing surface using an electrospinning method with an average diameter ranging from 612 nm to 698 nm and relatively high Q–factors (rigid coating). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the PVAc nanofiber surface morphology, confirming its high surface area and roughness, which are beneficial in improving the sensor sensitivity compared to its thin-film counterpart. The as-spun PVAc nanofiber sensor could demonstrate a safrole limit of detection (LOD) of down to 0.7 ppm with a response time of 171 s and a sensitivity of 1.866 Hz/ppm. It also showed good reproducibility, rapid response time, and excellent recovery. Moreover, cross-interference of the QCM sensor response to non-target gases was investigated, yielding very low cross-sensitivity and high selectivity of the safrole sensor. Owing to its high robustness and low fabrication cost, this proposed sensing device is expected to be a promising alternative to classical instrumental analytical methods for monitoring safrole-based drug precursors.

Some of the technical problems that appear are obtaining solar cell parameters from I-V curve measurement data. One simple method is using linear graphical fit at zero current or voltage conditions. Although the accuracy of the obtained values is acceptable, other problems may arise regarding the number of parameters which could be obtained. We report a comparison between manual or graphical fit and fit using Shockley's equation. The single I-V curve under the lighting was inferred to obtain the intrinsic parameters of the solar cells' performance. The fittings were performed using the nonlinear equation of Shockley by determining some initial values of fittings such as R s , R sh , n, I 0 , I ph , and T. In the case of the Shockley equation fit, the iteration was performed several times to obtain the least possible inferred parameters. We have successfully obtained a better result of nonlinear Shockley fitting compared to the manual linear fit.

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Beta-carotene dye which is extracted from daucus carota material was used as sensitizer to fabricate dye-sensitized solar cell (DSSC). DSSCs were arranged in a sandwich structure consisting of fluorine-doped tin oxide (FTO) as a transparent conducting oxide (TCO), titanium dioxide (TiO2) layer, beta-carotene dye, iodide/tri-iodide redox electrolyte, and carbon layer as a counter electrode. Beta-carotene dye has an absorbance in wavelength zones from 415 to 508 nm. Meanwhile, it has the largest photoconductivity of 28.3×10-4 and 8.2×10-4(Ω.m)-1 in dark and bright conditions, respectively. Moreover, the photoelectrochemical performance of the DSSC based on beta-carotene dye showed that the maximum voltage of 23.9×10-2V and the maximum current of 3.3×10-5A. However, the photo-to-electric conversion efficiency of this DSSC was very low i.e. 12.5×10-4%.

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