The widely used rigid gas permeable (RGP) contact lenses provide higher oxygen permeability and tear exchange rate than do soft contact lenses. However, their wettability warrants improvement to enhance the wearing comfort. This study used UV laser (wavelength = 355 nm) to modify the surface properties of RGP contact lenses with materials of Boston XO^® (Bausch & Lomb Incorporated). Briefly, the mesh pattern was fabricated on the RGP contact lens surface by using the laser and smoothed by using oxygen plasma; the enhanced hydrophilic efficiency was analyzed using contact angle measurement. The experiment results indicated that the contact angle of the lens material decreased by approximately 10°–20° when the pitch of mesh pattern was <50 μm under a 500-mm/s scanning speed. The oxygen plasma enhanced surface wettability with a decreased contact angle (40°). The hydrophilic characteristic of the UV laser and oxygen plasma–treated surface was twice that of oxygen plasma–treated and untreated surfaces. In the future, RGP contact lens edges could be treated with UV laser and oxygen plasma to enhance the tear wettability and wearing comfort.

Optical measurement is conducted by employing components such as a spectrometer or photodiode (PD) to detect light intensity. However, the size of spectrometer is large because of its complex optical path and component. Moreover, a PD usually detects the total light intensity instead of the intensity of light at a specific wavelength. Therefore, a novel inverse light-emitting diode (LED) sensor was developed to measure light intensity at specific wavelengths because of the reverse effect of LEDs. In the experiments conducted in this paper, red, green, and blue LEDs were used in combination as the inverse LED sensor and light source. Moreover, commercial equipment such as a PD, an illuminometer, a power meter, and Actiwatch 2 were simultaneously employed to detect the light intensities. The results revealed that the intensity ratio evaluated using the inverse LED sensor was proportional to that of the light source. This implies that the correlation between the incident light and measured intensities from the proposed inverse LED sensor was stronger than commercial equipment. The relationship between intensity ratio, irradiance distance, and illumination angle was also determined. The least difference between the measured and ideal evaluated intensity ratio was 2.4%. The proposed inverse LED sensor has following advantages: low cost, small size, high-wavelength selectivity, and high-intensity correlation. In a future study, light intensity can be measured using wearable devices comprising the proposed inverse LED sensor, and the presented relationship can be evaluated to investigate the effect between the light intensity and physiological mechanisms or diseases.

Indium tin oxide (ITO) is widely used as a substrate for fabricating chips because of its optical transparency, favorable chemical stability, and high electrical conductivity. However, the wettability of ITO surface is neutral (the contact angle was approximately 90°) or hydrophilic. For reagent transporting and manipulation in biochip application, the surface wettability of ITO-based chips was modified to the hydrophobic or nearly hydrophobic surface to enable their use with droplets. Due to the above demand, this study used a 355-nm ultraviolet laser to fabricate a comb microstructure on ITO glass to modify the surface wettability characteristics. All of the fabrication patterns with various line width and pitch, depth, and surface roughness were employed. Subsequently, the contact angle (CA) of droplets on the ITO glass was analyzed to examine wettability and electrical performance by using the different voltages applied to the electrode. The proposed approach can succeed in the fabrication of a biochip with suitable comb-microstructure by using the optimal operating voltage and time functions for the catch droplets on ITO glass for precision medicine application. The experiment results indicated that the CA of droplets under a volume of 20 μL on flat ITO substrate was approximately 92° ± 2°; furthermore, due to its lowest surface roughness, the pattern line width and pitch of 110 μm exhibited a smaller CA variation and more favorable spherical droplet morphology, with a side and front view CA of 83° ± 1° and 78.5° ± 2.5°, respectively, while a laser scanning speed of 750 mm/s was employed. Other line width and pitch, as well as scanning speed parameters, increased the surface roughness and resulted in the surface becoming hydrophilic. In addition, to prevent droplet morphology collapse, the droplet’s electric operation voltage and driving time did not exceed 5 V and 20 s, respectively. With this method, the surface modification process can be employed to control the droplet’s CA by adjusting the line width and pitch and the laser scanning speed, especially in the neutral or nearly hydrophobic surface for droplet transporting. This enables the production of a microfluidic chip with a surface that is both light transmittance and has favorable electrical conductivity. In addition, the shape of the microfluidic chip can be directly designed and fabricated using a laser direct writing system on ITO glass, obviating the use of a mask and complicated production processes in biosensing and biomanipulation applications.

Silicon carbide (SiC), as a key material in the third-generation semiconductor industry, holds critical importance due to its superior thermal conductivity, high breakdown voltage, and wide bandgap. However, the conventional chemical mechanical polishing (CMP) process used in SiC wafer manufacturing is time-consuming and resource-intensive, involving significant material consumption and prolonged processing times. In this study, we explored the application of laser-assisted dry ablation as a pre-treatment for CMP. The experimental results showed that the single laser ablation depth of SiC is about 2 μm, and demonstrated that a laser spot overlap rate between 30% and 60% can generate a relatively lower surface roughness of SiC. This optimal range of overlap ensures a smoother ablation process, minimizing the irregularities on the SiC wafer surface. After a single pass of laser dry ablation, SiC hardness can be reduced to less than 3% of its original value, while material removal depth can be precisely controlled by adjusting the number of laser passes. With 50 repetitions, a material removal depth of nearly 30 μm was achieved. This reduction in hardness and enhanced material removal directly contribute to improve the efficiency of subsequent CMP processes by reducing polishing time and wear on grinding heads. In addition, after more than 5 times of laser treatment and then wet grinding, the thickness achievement rate can be increased from 73 to 93%. These results provide the important academic reference value. The integration of laser-assisted ablation into SiC wafer processing presents significant advantages in terms of increasing production throughput and reducing overall manufacturing costs. By simplifying the polishing steps and minimizing consumable usage, this approach offers a promising avenue for industrial applications, particularly in enhancing SiC wafer yield and optimizing semiconductor production workflows.

Silicon carbide (SiC) has significant potential as a third-generation semiconductor material due to its exceptional thermal and electronic properties, yet its high hardness and brittleness make processing costly and complex. This study introduces ultraviolet laser ablation as a method for direct SiC material removal, investigating the effects of varying scanning speeds on surface composition, hardness, and ablation depth. The results indicate optimal processing speeds for the Si and C faces at 200 mm/s and 100 mm/s, respectively. Ablation depth is linearly correlated with laser repetitions, achieving a 25% improvement in removal efficiency at 100 mm/s on the C face compared to higher speeds. A composition analysis shows that the Si and C faces of SiC exhibit consistent ratios of Si, O, and C both before and after ablation. Post-ablation, the proportion of Si and C decreases with an increased presence of oxygen. At scanning speeds below 200 mm/s, the variation in speed has minimal effect on the compositional ratios, indicating a stable elemental distribution across the surface despite differences in processing speed. Hardness testing indicates an initial hardness of 13,896 MPa for the C face, higher than that of the Si face, with both surfaces experiencing a drop to less than 1% of their original hardness (below 50 MPa) after ablation. Lattice structure analysis shows Moissanite-5H SiC and cubic silicon formation on the Si face, while the C face retains partial SiC structure. This study found that when laser parameters are used to process SiC, the processing parameters required on both sides are different and provide important reference information for future industrial processing applications to shorten the time and process cost of SiC surface thinning.