As a clue to the clarification of the polishing principle of CMP, the surface topography of the polishing pad was observed using a confocal microscope. It was confirmed that pad surface protrusions, which are thought to contact wafers during polishing and contribute to polishing, are formed mainly at the upstream portion of the pore edge in the flow direction. In this paper, the relationship between the projection shapes formed on the pore edges and the pore depths is discussed.

This research discusses the development of an Optical Microneedle Lens Array (OMLA) for Photodynamic Therapy (PDT), a treatment widely used for diseases like port-wine stain and non-melanoma skin cancer. The OMLA is designed to improve the safety and efficiency of PDT by facilitating the delivery of photosensitizers (PS) and the application of excitation light. The OMLA was tested using a Monte Carlo simulation, which showed that light energy deposition in skin with OMLA increased significantly compared to naked skin. A physical model of the dip-coating process was built to find the optimal parameters. This research also details the process of loading PS onto the microneedle part of the OMLA using a dip-coating method. The results showed that about 1.5 μg of TMPYP, a type of PS, was loaded onto the microneedles. This research also uses red fluorescence by TMPyP, as an indicator of successful photosensitizer delivery into skin using an OMLA for PDT. This research concludes that the OMLA for PDT could satisfy various demands for the treatment of skin cancer or other illnesses. Future experiments will be carried out to verify the PDT effect.

Microneedles (MNs) have emerged as a reliable platform for various biomedical applications because they can penetrate human skin and access the dermal interstitial fluid (ISF) in a minimally invasive way. Porous MNs with interconnected pores inside can extract the ISF from the dermal layer via capillary force, which can be utilized for biomarker analysis in ISF. In this study, we fabricated a porous MN array with adjustable ISF extraction ability using microfluidic technology. Monodisperse PLA microspheres with diameters ranging from 10 to 40 μm were prepared with a low coefficient of variation (CV = 2-5%) using microfluidic technology. PLA porous microneedle array was fabricated by thermal bonding the microspheres under optimized conditions of 140 degree, 15 KPa for 60 min to achieve a continuous network of interconnected channels inside the needle. Pore size distribution in the MNs was varied by changing the microsphere diameter to adjust the ISF extraction efficiency. The fabricated MN array could absorb 8.2 μL sample fluid from skin model made with agarose gel within 5 min. It is expected that the proposed fabrication of porous MNs with adjustable ISF extraction efficiency can fulfill various demands from different fields as well as applications.

Detecting pH at the single-cell level holds great clinical significance for early disease detection, such as cancer and diabetes. In this study, we present a novel design for miniaturized microneedle potentiometric sensors based on AgIO₃/Ag/PTFE/WO₃/W, enabling real-time label-free pH measurement in various bodily fluids. The fabrication process involves several steps, including the creation of tungsten (W) microneedles and deposition of AgIO₃/Ag/PTFE/WO₃ layers. By employing electrolytic polishing, a needle-like structure is formed at the end of cleaved W rods. The working electrode (WE) consists of tungsten oxide (WO3) films, which are thermally oxidized onto the W microneedles. Polytetrafluoroethylene (PTFE) was coated over a needle-shaped WO₃/W rod as an insulating layer between the WE and the reference electrode (RE, AgIO₃/Ag thin film). The PTFE and AgIO₃/Ag layers are fabricated using the spray method and RF sputtering technique, respectively. Comprehensive analysis using XRD, Raman, FESEM, EDS, and XPS techniques confirms the microstructural and compositional features of the developed AgIO₃/Ag/PTFE/WO₃ microneedle sensors. The fabricated miniaturized microneedle sensors showed desirable analytical performance characteristics, including a Nernstian slope of -49.44 mV/pH, and a linear response range from pH 4.01 to pH 9.18 as determined through testing in a pH standard solution. Moreover, the ex vivo pH test on fish eggs demonstrates the capability of our fabricated miniaturized microneedle pH sensors to penetrate biological tissue and accurately measure pH values.

Cell-based therapies would greatly benefit from the ability to extract, modified target viable cells from a mixed cell population with minimal manipulation. Current approaches to cell processing involve conducting intracellular delivery and cellular manipulation separately using optoporation and laser manipulation, which require different light sources and optics. Therefore, sharing the same light source and optics for both introducing foreign molecules and collecting cells would simplify the experiments. In this work, beta-carotene embedded gelatin film was used as a photosensitizer element, and a nanosecond pulsed laser (continuous mode) was scanned to deliver PI into HeLa cells at different beta-carotene concentrations and laser fluence. Single pulse irradiation (burst mode) displaced polystyrene beads and its displacement was evaluated to demonstrate the possibility of cell manipulation. Nanosecond pulsed laser irradiation of beta-carotene microparticle-embedded gelatin films generated shockwaves and facilitated intracellular delivery and manipulation of polystyrene particles, thus dual applications of the laser shockwave were showcased.

This research is a study on component separation using a spiral microfluidic device. Although many studies on spiral microfluidic devices have been reported so far, it is known that they are not suitable for collecting objects with small particle diameters (especially 5 μm or less in diameter). In this research, we succeeded in increasing the collection efficiency by lowering the particle concentration in the suspension. In the case of particles with a diameter of 3 μm, it was confirmed that the P value decreased to 1% or less by decreasing the concentration.