This study optimized the extraction conditions to maximize the recovery yields of quercetin and total flavonoids from red onion skin waste using sequential microwave/ultrasound-assisted extraction. Five effective factors of quercetin extraction yield were investigated using response surface methodology. The method was successfully performed under optimal 60 s microwave irradiation conditions followed by 15 min sonication at 70 °C with 70% (v/v, water) ethanol with a solvent-to-solid ratio of 30 mL/g. The variance analysis of the model for both quercetin (Y₁) and total flavonoid (Y₂) recovery from DOS demonstrated that ultrasound temperature (X₂) was the most highly significant and influential factor, with a p-value of <0.0001 for both responses. Additionally, three key interaction terms—X₁X₂, X₂X₄, and X₂X₅—were identified as highly significant, further underscoring the critical role of ultrasound temperature in optimizing the extraction process for both quercetin and total flavonoids. The maximum recovery yields of quercetin and total flavonoids from red onion skin were 10.32% and 12.52%, respectively. The predicted values for quercetin (10.05%) and total flavonoids (12.72%) were very close to the experimental results. The recovery yields obtained from different extraction methods under the identical experimental conditions mentioned earlier were ultrasound/microwave-assisted extraction (7.66% quercetin and 10.18% total flavonoids), ultrasound-assisted extraction (5.36% quercetin and 8.34% total flavonoids), and microwave-assisted extraction (5.03% quercetin and 7.91% total flavonoids). The ANOVA confirmed highly significant regression models (p-values < 0.0001), with an insignificant lack of fit (p = 0.0515 for quercetin, p = 0.1276 for total flavonoids), demonstrating the robustness and reliability of the optimization. This study provides valuable insights for improving the extraction of bioactive compounds, which is critical for developing effective cancer treatments and advancing medical research. Additionally, the model shows potential for scaling up food processing applications to recover valuable products from red onion skin waste.

Hematology tests, considered as an initial step in the patient diagnostic process, require laboratory equipment and technicians which is a time- and labor-consuming procedure. Such facilities may be available in a few central laboratories in under-resourced countries. The growing need for low cost and rapid diagnostic tests contributes to point-of-care (POC) medical diagnostic devices providing convenient and rapid test tools particularly in areas with limited medical resources. In the present study, a comprehensive numerical simulation of a POC blood cell separation device (POC-BCS) has been modeled using a finite element method. Tag-less separation of blood cells, i.e., platelets, red blood cells, and white blood cells, was carried out using standing surface acoustic waves (SSAWs) generated by interdigital transducers (IDTs) located at lateral sides of the microfluidic channel. Blood sample intake along with sheath flow was introduced via two symmetrical tilted angle inlets and a middle inlet, respectively. Superposition of acoustic radiation force applied by SSAWs accompanied by drag force caused by medium flow drove the blood cells toward different path lines correlated to their size. White blood cells were sorted out in the middle outlet and red blood cells and platelets were sorted out through the separate locations of the side outlets. Each cell was then guided to their respected visualization chamber for further image processing analysis. The results of the presented numerical study would be very promising in designing and optimizing the POC blood testing device.

Two-photon polymerization enables neural probes with complex three-dimensional geometries, but selectively metallizing and insulating these structures remains challenging. We present a geometry-defined fabrication process that combines trench-guided metallization with vapor-deposited Parylene-C encapsulation and lithography-free electrode exposure. Re-entrant trenches guide line-of-sight Ti/Au evaporation to form electrically separated interconnects connected to electrode sites and contact pads. A conformal Parylene-C coating then seals the high-aspect-ratio trenches over the interconnects, and a timed, maskless O₂ plasma etch-back followed by SF₆/O₂ plasma treatment exposes the electrodes and pads while retaining insulation over the recessed interconnects. We fabricated a prototype comprising a 2 mm-long shank with four mushroom-shaped electrodes, each 15 µm in diameter. Scanning electron microscopy showed metal deposition at the trench bottoms, Parylene-C coverage, and selective electrode exposure after plasma processing. Electrochemical impedance spectroscopy in phosphate-buffered saline showed an impedance magnitude of approximately 1 MΩ at 1 kHz before and after insertion into 0.6% agarose gel. The probe reached a 2 mm insertion depth without observed buckling or fracture. These results demonstrate a fabrication proof of concept for 3D-printed neural probes using geometry-defined metallization and selective Parylene encapsulation, providing a potential route toward scalable fabrication of 3D-printed bioelectronic microsystems