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Cross striation in human permanent and deciduous enamel measured with confocal Raman microscopy
摘要： Dental enamel is the most mineralized tissue in the human body and has a very complex organization. The aim of the present study was to evaluate chemical composition and orientation of crystals in human enamel cross striation using confocal Raman microscope. Slices of teeth were prepared and scanned using a confocal Raman microscope. Cross striation spacing was calculated according to the variation of PO4 3? peak intensity. The measurements showed a characteristic length between two cross striations of 2.70 (SD 0.43) μm for permanent teeth and 1.75 (SD 0.37) for deciduous teeth. Ratios between OH and PO4 3? peaks, for 0 and 90 degrees angulation, are, respectively, 9.18 (SD 0.80) and 44.74 (SD 3.12) for decidual teeth, and 11.72 (SD 1.46) and 22.12 (SD 3.15) for adult teeth. This confirmed that the hydroxyapatite crystal is well oriented along the enamel prism, as reported in the literature, but with a significant increase in deciduous teeth. K‐mean cluster binary images were calculated to compare the ratio of the centroid peaks of the cross striation zone and inter cross striation material. The regions corresponding to inner prism, included cross striations, are more mineralized than the outer part of enamel prism. In the prism, the Pearson correlation test was performed based on the intensity of hydroxyapatite characteristic peaks (ν1 PO4 3?, ν1 CO3 2?, and OH). The variations were well correlated: These results indicated that cross striations corresponded to the variation of hydroxyapatite concentration and not to a variation of crystals orientation.
关键词： Raman microscopy,cross striation,enamel prism,K‐mean cluster analysis,decidual teeth
更新于2025-09-23 15:23:52
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A Novel Hybrid Removal Technology for High-Aspect-Ratio SU-8 Micromolds in ECF (Electro-Conjugate Fluid) Micropumps Fabrication by UV-LIGA
摘要： Previously, we have developed ECF micropumps with triangular prism and slit electrode pairs (TPSEs) fabricated by the UV-LIGA. However, the previous KMPR molds have a limit to attain higher-aspect-ratio TPSEs. As a promising substitute, the ultrathick SU-8 molds are preferable for the TPSEs due to higher-aspect-ratio ability, but their difficult removal remains an annoying problem. To solve this problem, we first propose a novel hybrid removal method combining CO2 laser engraving with O2/CF4 plasma to achieve the fast, non-swelling, and complete removal of ultrathick SU-8 micromolds for higher-aspect-ratio TPSEs. The CO2 laser engraving is utilized as the main process to remove most SU-8, while the O2/CF4 plasma is adopted as the post-treatment to remove the remaining SU-8. To gather the proper fabrication conditions, we quantitatively analyze the effects of laser power, laser scan speed, and laser-pass numbers on the SU-8 ablation thickness. We successfully fabricated TPSEs of 590 μm and 970 μm in height by selectively removing SU-8 micromolds of 620 and 1100 μm in thickness. This achievement confirmed that our hybrid removal technology could remove the crosslinked SU-8 effectively and efficiently. We further experimentally proved the fascinating potential of our hybrid removal in improving the output performance of ECF micropumps. This promising hybrid removal opens the door to the easier fabrication of ultrathick metallic microstructures by UV-LIGA.
关键词： high aspect ratio,ECF micropump,CO2 laser engraving,SU-8 removal,triangular prism & slit electrode pair
更新于2025-09-23 15:22:29
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Study on non-isothermal hot-embossing of polymer micro-prism array with efficiency and accuracy
摘要： The isothermal hot-embossing leads to inefficiency because of heating and cooling whole polymer workpiece for precision micro-forming. Hence, a non-isothermal hot-embossing is proposed by compressing and melting a micron-scale surface layer into heated core microgrooves without changing the solid-state workpiece. The objective is to understand how the upper layer micro-prism array is formed on large-size polymer surface with regard to core microgroove parameters and hot-embossing variables. First, the micro-prism shape and sizes were in-process modeled through a hybrid of mechanical compression and hot-melt flowing inside core microgrooves; then the micro-grinding with the trued wheel micro-tip was employed to fabricate various microgrooves on macro-size die cores; finally, the micro-forming accuracy and efficiency were experimentally investigated in hot-embossing. It is shown that the integrated micro-prism array with nanometer-scale surface roughness is rapidly generated inside accurate and smooth core microgrooves with 1-3 seconds. The micro-forming accuracy is dominated by the hot-embossing variables under the limitations of core microgroove parameters. Moreover, the hot-embossed surface roughness reaches 10-30 nm through the hot-melt layer flowing even if the core surface roughness is larger. It is confirmed that the rapid micro-forming sizes and surface roughness may be predicted by the micro-nano core topographies and the hot-embossing variables.
关键词： micro-forming,die core,micro-grinding,hot-embossing,LGP,micro-prism array
更新于2025-09-23 15:21:21
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Optimized sample addressing in prism-coupled surface plasmon resonance experiments
摘要： In this work we study the walk-off of the beam from the interrogation spot during rotation in surface plasmon resonance experiments using prism-based coupling such as the widespread Kretschmann configuration. The impossibility of maintaining a stationary footprint on the sensing surface with a fixed rotation axis can be of high importance. This would be specially so if samples are not homogeneous such as in arrays for multiplexing. By theoretically analyzing the behavior of the walk-off during rotation around an arbitrary fixed axis, we find an optimal and simple configuration to minimize this effect. The proposed setup is experimentally tested to verify the results and to show its ease of implementation. Interestingly, the conclusions reached may also be applied to other techniques employing reflection prisms.
关键词： Rotation axis,Surface plasmon resonance (SPR),Alignment optimization,Prism coupling,Walk-off
更新于2025-09-23 15:21:01
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Single-grain growth in Si film by chevron-shaped cw laser beam scanning
摘要： A single grain with a length of 450 μm and a width of 5–6 μm was grown in a 60 nm Si ?lm on SiO2 by scanning a chevron-shaped cw laser beam, which was formed by passing a linear laser beam through a novel one-sided Dove prism. The crystal did not have any dominant orientations in both the growth and normal directions. The orientation rotated about the transverse direction at a rate of 0.47–0.51°/μm in the forward direction, which suggests that the lattice constant at the ?lm surface was 0.049–0.053% larger than that at the ?lm bottom.
关键词： crystal orientation,one-sided Dove prism,single-grain growth,chevron-shaped cw laser beam,Si film
更新于2025-09-19 17:13:59
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[IEEE 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Berlin, Germany (2019.6.23-2019.6.27)] 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - A Microassembled Triangular-Prism-Shape Three-Dimensional Electric Field Sensor
摘要： This paper, for the first time, presents a microassembled three-dimensional (3D) electric field sensor (EFS), which is a chip-level compact triangular-prism-shape sensor consisting of X-, Y- and Z-axis electric field (EF) sensing chips. The proposed 3D EFS is fabricated on a silicon-on-insulator (SOI) die, introducing photosensitive polyimide (PSPI) into its micromachining process to produce flexible micro-hinges and make separate components into a foldable integrative structure. Interlocking latches are employed to ensure the orthogonality of the three sensing axes. Structures of each EF sensing chip are symmetrically designed for reducing cross-axis coupling interference, and good performances have been demonstrated by experiments.
关键词： microassembly,Electric field sensor,triangular-prism-shape,three-dimensional,photosensitive polyimide
更新于2025-09-16 10:30:52
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A Method for Improving Light Intensity Stability of a Total Reflection Prism Laser Gyro Based on Series Correction and Feedforward Compensation
摘要： The instability of scale factor and null shift are closely related to the change of the light intensity of a total re?ection prism laser gyro (TRPLG). To improve the light intensity stability, the light intensity stabilization principle of TRPLG was analyzed, and a mathematical model of light intensity stabilization system was established. Aiming at the problem that original system has a long adjustment time, a series correction method of adding a proportional integral differential (PID) link in the forward channel was adopted. According to the third-order optimal design, the original I-type third-order overdamped system was optimized to the new II-type third-order underdamped system, which ultimately improved the system’s dynamic and steady-state performance. Feedforward compensation was used to introduce the light intensity disturbance during the longitudinal mode hopping into the closed-loop system, which realized the full compensation of the light intensity error and improved the light intensity characteristics during the longitudinal mode hopping. Combined with the above two methods, experimental results showed that the new system with feedforward compensation improved the light intensity stability by 32% at constant temperature and by 40% at variable temperature, with the TRPLG’s bias stability improved by more than 16% at constant temperature and by 22% at variable temperature.
关键词： light intensity stability,dynamic and steady-state performance,feedforward compensation,bias stability,series correction,Total re?ection prism laser gyro
更新于2025-09-16 10:30:52
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Holey metasurface prism for the reduction of the dispersion of gap waveguide leaky-wave antennas
摘要： Leaky-wave antennas (LWA) are dispersive, meaning that the direction of maximum radiation is a function of frequency. This behavior, called “beam squinting effect” can be reduced by introducing a dispersive metamaterial prism. In this paper a holey metasurface prism is combined with a leaky-wave antenna in gap waveguide technology. The dispersion characteristics of the hole unit cell are studied in order to achieve the reduction of the main beam steering aiming to ±1o or less variation. A prototype designed at the Ka band is measured and compared with the simulation results.
关键词： groove gap waveguide,leaky-wave antenna,metasurface prism,dispersive radiation pattern
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE 2nd Ukraine Conference on Electrical and Computer Engineering (UKRCON) - Lviv, Ukraine (2019.7.2-2019.7.6)] 2019 IEEE 2nd Ukraine Conference on Electrical and Computer Engineering (UKRCON) - Properties of Planar Waveguide With Gain (Absorption), Applied on a Glass Prism
摘要： Structure that consists of glass prism, with successively applied two dielectric layers with small and high refractive indices has been analyzed using matrix method. Moreover, the second waveguide layer has complex refraction index. In the case of absorbing layer, for optical waves with certain wavelengths and angles of incidence, the reflection coefficient is equal to zero. In the other case, where the dielectric layer with complex refractive index has amplifying properties, the reflection coefficient at certain wavelengths and angles of incidence becomes significantly high.
关键词： absorption,waveguide,prism,laser,amplification
更新于2025-09-11 14:15:04
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Field Expansion for Acquired Monocular Vision Using a Multiplexing Prism
摘要： SIGNIFICANCE: Acquired monocular vision (AMV) is a common visual field loss. Patients report mobility difficulties in walking due to collisions with objects or other pedestrians on the blind side. PURPOSE: The visual field of people with AMV extends more than 90° temporally on the side of the seeing eye but is restricted to approximately 55° nasally. We developed a novel field expansion device using a multiplexing prism (MxP) that superimposes the see-through and shifted views for true field expansion without apical scotoma. We present various designs of the device that enable customized fitting and improved cosmetics. METHODS: A partial MxP segment is attached (base-in) near the nose bridge. To avoid total internal reflection due to the high angle of incidence at nasal field end (55°), we fit the MxP with serrations facing the eye and tilt the prism base toward the nose. We calculated the width of the MxP (the apex location) needed to prevent apical scotoma and monocular diplopia. We also consider the effect of spectacle prescriptions on these settings. The results are verified perimetrically. RESULTS: We documented the effectivity of various prototype glasses designs with perimetric measurements. With the prototypes, all patients with AMV had field-of-view expansions up to 90° nasally without any loss of seeing field. CONCLUSIONS: The novel and properly mounted MxP in glasses has the potential for meaningful field-of-view expansion up to the size of normal binocular vision in cosmetically acceptable form.
关键词： prism glasses,visual field loss,field expansion,multiplexing prism,Acquired monocular vision
更新于2025-09-10 09:29:36