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CO2 laser interactions with wood tissues during single pulse laser-incision
摘要： Incising is a technique used to improve fluid flow in impermeable woods during wood treatment processes. Previous studies relating to the laser-incision of wood have neglected many aspects such as detailed analysis of the anatomy of the wood, including consideration of tangential/radial faces and earlywood/latewood interactions with the laser beam. By considering wood anatomy, a complete investigation of the CO2 laser-incision processes is presented that yields new knowledge of laser beam interaction with growth rings when incising into tangential/radial faces, and the low-density earlywood and higher density latewood within the growth ring. Southern Yellow Pine, Radiata Pine, European Redwood and Beech, each having different bulk densities, were laser-incised using a 2 kW ROFIN CO2 laser with radiation in the far-infrared regime (10.6 μm). Microstructural characterisations were carried out to better understand the effect of CO2 laser-incision and its parameters on the depth, diameter and quality of the incised holes. The laser-incised hole shapes were found to be uniform in depth, however, the hole circularity was significantly affected by the presence of earlywood and latewood tissues. Maximum and minimum diameters of incised holes were measured in the Radiata Pine (~1.3 mm) and in the Beech (~0.7 mm), respectively. Similarly, for equal laser powers used, the maximum and minimum depths of laser-incised holes were measured in the European Redwood (~33 mm) and in the Beech (~25 mm), respectively, with the laser incident on the radial face of the samples. CO2 laser pulse duration had a greater effect on diameter and depth of incised holes when compared to laser power and showed that the CO2 laser pulse duration is a dominant parameter when designing CO2 laser-incision processes.
关键词： Laser-incision,Wood,Circularity,Depth,Diameter,CO2 laser
更新于2025-11-21 11:24:58
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Vehiculización de fármacos asistida por láser
摘要： Absorption of topical products through the epidermis is limited by the skin's barrier function. Numerous techniques and agents such as microneedling, dermabrasion, radiofrequency, and lasers have been used to increase penetration within an approach known as transdermal drug delivery. One of these techniques is laser-assisted drug delivery (LADD), which often uses ablative fractional lasers (CO2 or erbium:YAG lasers) because of their capacity to produce microscopic ablated channels. The parameters in LADD need to be adjusted to the patient, the skin condition and its location, and the drug. LADD has been used with various topical products, such as corticosteroids, photosensitizers, and immunotherapy agents (imiquimod or 5-fluorouracil) to treat numerous conditions, including scars, nonmelanoma skin cancer, and photodamage. LADD is a promising technique that enhances the absorption of topical molecules while adding the synergic effect of the laser.
关键词： Laser-assisted drug delivery,CO2 laser,Ablative fractional laser,Hypertrophic scars,Keloid scars
更新于2025-09-23 15:23:52
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The influence of the thermal wake due to pulsating optical discharge on the aerodynamic-drag force
摘要： The influence of a thermal wake due to gas injection and due to a pulsating optical discharge (POD) on the aerodynamic-drag force of a body in a supersonic air flow with Mach number M = 1.45 are experimentally examined. With the help of a single-component aerodynamic balance, the influence of the injected subsonic jet and the thermal wake produced by POD on the aerodynamic drag of a hemisphere-on-cylinder model was studied. It is shown that the observed aerodynamic-force reduction phenomenon can be made more pronounced by increasing the laser power and pulse repetition frequency, or by decreasing the distance between the model and the pulsating optical discharge. The maximum aerodynamic-force reduction (up to 15%) due to the thermal-wake action was observed at a maximum laser-radiation power of W = 2.3 kW and at a pulse rate of f = 90 kHz. The joint effect due to the argon jet and due to the POD caused an aerodynamic-drag force reduction reaching 30%.
关键词： thermal wake,gas injection,CO2-laser,supersonic flow,pulsating optical discharge,aerodynamic-drag force
更新于2025-09-23 15:23:52
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Superstructure Fiber Bragg Gratings for Simultaneous Temperature and Strain Measurement
摘要： A new and simple fiber optic sensor based on a superstructure fiber Bragg grating (SFBG) for simultaneous temperature and strain measurement is proposed. The SFBG is a superimposed grating for which a long period fiber grating (LPG) and a fiber Bragg grating (FBG) is written in the same section of a Corning SMF-28 fiber. The reflection spectrum of the SFBG possesses two resonant peaks and a trough. By measuring the wavelength shift of the main resonant peak and the reflection power change of the trough, temperature and strain can be determined simultaneously. The accuracy of the sensor in measuring strain and temperature is estimated to be ±13.01 με in a range from 0 με to 1000 με and ±0.75 ℃ from 20 ℃ to 100 ℃, respectively.
关键词： CO2 laser,SFBG,simultaneous measurement of temperature and strain,fiber optic sensor
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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Influence of gold nanolayer coating on the continuous-wave laser ablation of a pure aluminum surface: Evaluations of structural and optical features
摘要： In this paper, formation of uniform and large-area micro/nanostructures on pure aluminum surfaces using a continuous-wave laser irradiation is presented. Gold nanolayer coating was utilized as a confinement layer for controlling the possible hydrodynamic phenomena in a molten area. Dependency of the laser-induced morphology on the thickness of a gold coating was investigated in this regard. Scanning electron microscopy, energy dispersive spectroscopy, grazing test of the X-ray diffraction, and optical absorption/reflection spectroscopy in UV/visible/IR ranges were employed to characterize the samples. Results showed that the formation of uniform structures of average sizes of 50 nm-5μm on aluminum surface was possible following the irradiation of a continuous-wave CO2 laser, delivering 130 W beam power. Alterations of the surface morphology brought about an increase in specific absorption peaks at the UV region and the appearance of an absorption peak in the visible range. In addition, these structure-covered surfaces provided interesting reflection behaviors in different spectral areas, which can clearly reflect their high potential to be used as selective solar absorbers. The results of this investigation indicated that optical characteristics such as absorption and emission coefficients as well as ξ factor were 0.98, 0.13, and 7.53, respectively. It can therefore be concluded that this process can be considered an efficient and fast technique to fabricate selective solar absorbers.
关键词： Nanostructures,Aluminum,Selective solar absorber,Sputtering,Nanolayer,Continuous-wave CO2 laser,Gold,Black carbon
更新于2025-09-23 15:22:29
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High Strain Sensitivity Temperature Sensor Based on a Secondary Modulated Tapered Long Period Fiber Grating
摘要： A novel sensor structure has been proposed and experimentally investigated for simultaneous strain and temperature measurement. The structure is fabricated by weak power modulation of CO2 laser exposure on tapered long period fiber grating (LPFG). Compared with the transmission spectrum of the tapered LPFG, two peaks appear in the transmission spectrum of the novel structure. These resonance peaks exhibit different sensitivity responses; thus, simultaneous measurement of strain and temperature is realized by monitoring the wavelength shift of the two peaks. Experiment results indicate that strain sensitivities of the two peaks are 1.82 pm/με and 8.17 pm/με, and temperature sensitivities are 47.9 pm/°C and 65 pm/°C, respectively.
关键词： strain,simultaneous measurement,temperature,Taper,CO2 Laser
更新于2025-09-23 15:22:29
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Safety evaluation of fractional CO2 laser treatment in post-menopausal women with vaginal atrophy: A prospective observational study
摘要： Objectives: To evaluate the safety of and patient satisfaction with fractional CO2 laser for the treatment of vulvo-vaginal atrophy (VVA) in postmenopausal patients. Study design: Patients affected by VVA were considered for the study. All women were treated using a Lumenis AcuPulse DUO (Lumenis, Yokneam, Israel) in fractionated mode with a 28 mm probe, FemTouch?. Pain during different steps of the procedure (introduction, rotation and extraction of probe and laser impulse transmission) was evaluated on a 7-point Likert scale. The occurrence of side-effects was evaluated at the end of the procedure, and in the three-month follow-up (after the last treatment) complications were classified as ‘early’ (occurring within 30 days) or late (after 30 days). Participant satisfaction was measured on a 7-point Likert scale (1= strongly disagree, 7= strongly agree). The institutional review board approved the study protocol. Results: Fifty-three women were enrolled in the study. No severe complications occurred after a median follow-up of six months. One patient (1.9 %) reported dizziness immediately after treatment, which completely resolved within 15 min. A minor bleeding occurred related to tip introduction and rotation. One patient (1.9 %) aborted the procedure because of discomfort on probe introduction but decided to repeat the procedure after two weeks. Two patients (3.7 %) reported symptoms of dysuria within 7 days of the procedure. The mean overall pain score at first treatment, evaluated on the 7-point Likert scale, was 3.57 ± 1.50. The mean pain scores related to probe introduction and rotation were 3.13 ± 1.37 and 2.32 ± 1.08, whereas pain scores for extraction and laser impulse transmission were 1.23 ± 0.27 and 1.13 ± 0.37 respectively. Mean overall pain score (1.27; CI 95 % 0.83–1.71, p < 0.001) and pain scores related to probe introduction (0.54; CI 95 % 0.18–0.90, p = 0.001) and probe rotation (0.46; CI 95 % 0.12–0.90, p = 0.003) all statistically significantly decreased between the first and third treatment (Fig. 1). Mean pain scores related to laser activation (0.01; CI 95 % ?0.06 – 0.20, p = 0.07) and extraction (0.08; CI 95 % ?0.04–0.19, p = 0.31) did not change over the course of treatment. Overall, patient satisfaction with the procedure was high: 89.7 % of patients would highly (value 5–7) recommend the procedure and 94.9 % would be ready to repeat the procedure to maintain results. Discomfort related to treatment was lower than expected for 41 % of patients (value 5–7) and as expected for 48.7 % (value 3–4). Conclusion: Fractional CO2 laser for treatment of VVA seems a safe therapeutic option. No severe complications occurred. A minority of patients reported mild complications, but these resolved without the need for treatment. Most discomfort was related to probe introduction and rotation. Overall, patients were highly satisfied, and they would repeat laser treatment.
关键词： Fractional CO2 laser,Dyspareunia,Menopause,Laser safety,Vulvovaginal atrophy
更新于2025-09-23 15:21:01
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[IEEE 2019 41st Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) - Berlin, Germany (2019.7.23-2019.7.27)] 2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Electrode design on plastic substrates using laser patterned double-sided tape and gold leaf
摘要： The production of electrodes and sensors using plastic substrates has increased substantially for the last decades. Although devices are fabricated using plastic substrates suitable for the purpose of each device, it is difficult to find a process that can be used commonly for most types of plastics. In this paper, two kinds of electrode fabrication process that can be applied to most plastic films using kapton double sided tape and gold leaf are proposed. One is for the plastic film with adhesive and the other is for the film without adhesive. First, the kapton double-sided tape was patterned using a CO2 laser. After transfer double-sided tape to desired substrate, release paper was detached and gold leaf was attached on the exposed side of the tape. Then, the tape was appropriately removed according to the presence or absence of the adhesive. After that, the packaging was performed using an adhesive when the used film has adhesive, and otherwise, heat press was used for packaging. These processes have a variety of advantages such as inexpensive, fast-running and commonly applicable to many plastics. To prove its usability, impedance and minimum line width was measured.
关键词： electrode fabrication,CO2 laser,kapton double-sided tape,plastic substrates,minimum line width,impedance,gold leaf
更新于2025-09-23 15:21:01
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Two-step treatment of bulky keloids on the cheeks after deep chemical peeling: intralesional cryosurgery followed by pulsed dye and ablative fractional CO2 laser
摘要： Scarring of the face following chemical peeling is an uncommon and devastating complication. This case report describes the successful treatment of bulky mature keloids on both cheeks following deep chemical peeling by using a combined approach of intralesional cryosurgery followed by pulsed dye and ablative fractional CO2 laser therapy.
关键词： Keloid,Silicone occlusive sheets,Deep chemical peeling,Pressure garment,PDL ablative fractional CO2 laser,Intralesional cryosurgery
更新于2025-09-23 15:21:01