CO2 Laser Research Articles

Characterization of a Bonding Method for High Borosilicate Glass to Kovar Alloy Sealing by Laser Welding

Glass to metal sealings have many excellent properties and they are extensively used in various industries. Applications for laser glass tube for carbon dioxide laser requires hermetic and mechanically strong seals. With the purpose of fully utilize its effectiveness of glass and metal sealings’ properties and enlarge their applications, bond the glass to metal is an important method. Hermetic seals between kovar alloy and borosilicate glass can be produced using a novel laser sealing method when compared to bonding method based on glass pressing at temperatures around the softening point. This paper presents investigation results for the shear tensile bond strength and the waterproof resistance depending on the manufacturing process parameters. The shear bond strength of the glass to metal sealing was amounted to only 9.84 MPa when using traditional high temperature holding process. The maximum shear bond strength can be amounted to 43.68 MPa when sealed by laser welding process. And good adherence with a very high waterproof resistance can ben obtained. The bonding mechanisms was revealed by SEM methods to analyze the interface.

Effects of CO2 laser parameters on quality of laser cut beech wood (Fagus sylvatica L) surface and extent of heat affect zone

Effects of CO2 laser parameters on quality of laser cut beech wood (Fagus sylvatica L) surface and extent of heat affect zone

Efficacy of Fractional CO2 Laser Therapy in Improving Symptoms and Quality of Life in Women with Refractory Vulvar Lichen Sclerosus: A Prospective Observational Study.

Lichen sclerosus (LS) is a chronic inflammatory condition predominantly affecting the anogenital region of postmenopausal women. It is associated with considerable aesthetic and functional impairments and an increased risk of squamous cell carcinoma. While high-potency topical corticosteroids remain the cornerstone of treatment, therapeutic options for patients with refractory LS are scarce. Fractional CO2 laser therapy has emerged as a potential second-line intervention aiming to mitigate symptoms and improve quality of life. This prospective observational study investigated the short-term efficacy and safety of fractional CO2 laser therapy in 75 women with refractory LS who underwent four treatment sessions between January 2022 and February 2024. Sixty-nine patients completed the protocol, demonstrating significant reductions in key symptoms, including pruritus (VAS score from 7.53 ± 3.02 to 4.08 ± 3.07), pain (5.83 ± 3.84 to 2.42 ± 2.85), and dyspareunia (8.26 ± 2.82 to 6.34 ± 3.30). Quality of life, sexual function, and psychological well-being also improved, as evidenced by reductions in Dermatology Life Quality Index (DLQI) scores (10.72 ± 7.25 to 5.94 ± 5.16), enhancements in sexual function (FSFI scores from 10.48 ± 8.46 to 15.52 ± 9.59), and decreased depression severity (BDI scores from 16.66 ± 12.64 to 5.94 ± 5.16). Importantly, no adverse effects were reported during the study period. Although these findings highlight the potential of fractional CO2 laser therapy as a safe and effective adjunct for refractory LS, it is essential to acknowledge the study's limitations, particularly the relatively short follow-up period. Longer-term studies are warranted to confirm sustained benefits and to evaluate the broader applicability of this approach.

Multi-pulse laser generation based on programming diffraction loss of acousto-optic Q-switched RF excited waveguide CO2 lasers

Acousto-optic Q-switched (AOQ-switched) CO2 lasers always suffer from having a laser pulse with a long tail and lower energy utilization. The ability of an acousto-optic modulator (AOM) to quickly program diffraction losses provides an effective method to solve these problems. In this paper, a six-temperature model is built to analyze the dynamical properties of the AOQ-switched CO2 laser with programmable control of the diffraction loss. The AOQ-switched laser pulse, or even the multi-pulse without a tail, can be achieved by precise adjusting of the delay time, pulse width, and pulse interval of the AOM control signal within a laser cycle. In the experiments, when the pulse width of the AOM control signal is reduced to 1 µs, the AOQ-switched laser pulse without the tail is obtained with a peak power of 1.36 kW and a pulse width of 132 ns at the repetition of 5 kHz. Meanwhile, equal energy double-pulse, triple-pulse, and quadruple-pulse lasers can be achieved by precisely programming the delay time and pulse interval of the AOM control signal. The average power has been significantly improved.

Line-field confocal optical coherence tomography coupled with artificial intelligence algorithms as tool to investigate wound healing: A prospective, randomized, single-blinded pilot study.

Ablative fractional photothermolysis serves as an excellent invivo model for studying wound healing. The advent of non-invasive imaging devices, such as line-field confocal optical coherence tomography (LC-OCT), enhances this model by enabling detailed monitoring of skin wound healing over time. Additionally, artificial intelligence (AI)-based algorithms are revolutionizing the evaluation of clinical images by providing detailed analyses that are unfeasible manually. This study aims to assess the value of combining LC-OCT and AI for evaluating the acute wound healing process in the skin. The forearms of participating volunteers were ablated with a CO2 laser in a fractional pattern (7.5 mJ/MTZ) (ClinicalTrials.gov identifier: NCT05614557). To induce observable wound healing differences, two different approved silicone-based formulations were randomly assigned to two test sites, with a third site left untreated. Invivo LC-OCT images were obtained at predefined intervals post-laser treatment, ranging from 1 to 7 days. These images were further analysed using AI algorithms. LC-OCT visualization allows for the characterization of the structural reorganization of the skin during wound healing. The additional integration of AI algorithms significantly enhances the evaluation of the efficacy of wound care interventions by providing a deeper understanding of how these interventions improve wound healing. This is particularly valuable for primary care providers and dermatologists, as AI algorithms have proven useful in observing, characterizing and understanding keratinocyte behaviour. The combination of AI and high-resolution imaging represents a promising tool for better understanding wound healing, evaluating the efficacy of current wound care interventions and analysing keratinocyte behaviour in detail during the wound healing process. NCT05614557.

Liquid Structure of Magnesium Aluminates.

Magnesium aluminates (MgO)x(Al2O3)1-x belong to a class of refractory materials with important applications in glass and glass-ceramic technologies. Typically, these materials are fabricated from high-temperature molten phases. However, due to the difficulties in making measurements at very high temperatures, information on liquid-state structure and properties is limited. In this work, we employed the method of aerodynamic levitation with CO2 laser heating at large scale facilities to study the structure of liquid magnesium aluminates in the system (MgO)x(Al2O3)1-x, with x = 0.33, 0.5, and 0.75, using X-ray and neutron diffraction. We determined the structure factors and corresponding pair distribution functions, providing detailed information on the short-range structural order in the liquid state. The local structures were similar across the range of compositions studied, with average coordination numbers of n¯AlO∼4.5 and n¯MgO∼5.1 and interatomic distances of rAlO=1.76-1.78 Å and rMgO=1.93-1.95 Å. The results are in good agreement with previous molecular dynamics simulations. For the spinel endmember MgAl2O4 (x = 0.5), the average Mg-O and Al-O coordination numbers gave rise to conflicting values for the inversion coefficient χ, indicating that the structural formula used to describe the solid-state order-disorder transition is not applicable in the liquid state.

Evaluation of Papain-Urea for Enzymatic Debridement of Coagulation Zones Following Ablative Fractional Laser Treatment.

Ablative fractional CO2 laser (10,600 nm) treatment creates an array of microscopic treatment zones composed of an ablation zone (AZ) surrounded by a denatured coagulation zone (CZ). The CZ is believed to play a functional role in skin tightening, posttreatment inflammation, and laser-assisted drug delivery. This study investigates the viability of enzymatic post-processing to remove the CZ without affecting the surrounding tissue. Ex vivo skin samples were treated with either control, papain, urea, or papain-urea solutions before being covered with occlusive dressing and incubated at 37°C for 1 h. Tissue viability as well as AZ and CZ geometries were assessed histologically. Treatment with all three experimental solutions resulted in a decrease in CZ. The largest average reduction in CZ area was observed in the papain-urea group (44%, p < 0.001), followed by the papain (14%, p < 0.001) and urea (11%, p < 0.001) only groups. Only the papain-urea group showed a significant increase in AZ (14%) and changes in lesion geometry. This exploratory study of enzymatic post-processing with papain-urea highlighted the potential of selectively removing the CZ after treatment with ablative fractional laser therapy. If results can be translated to in vivo studies, these findings could expand the use of high-fluence CO2 laser therapy with functional implications for lowering posttreatment recovery time, providing clinicians more control over skin tightening, and enabling a broader range of laser-assisted drug delivery.

Discolouration and Chemical Changes of Beech Wood After CO2 Laser Engraving

This study evaluated the influence of infrared laser radiation produced by a CO2 laser, performing under different engraving parameters, on the colour changes and chemical composition of a beech wood surface. The results showed that the lightness clearly decreased with increasing laser power and density. At the highest laser power and the highest raster density, the ΔL* value was 51.3. The values of coordinates a* and b* moderately increased up to a raster density of 5 mm−1; then, with a subsequent raster density increase, the values of these coordinates decreased again. However, the coordinate values were positive in all cases. Even the lowest laser power and raster density resulted in conspicuous discolouration or even a completely new colour compared to the original (ΔE = 10) of the beech wood surface. Further increases in the laser power and raster density resulted in progressively pronounced colour differences and a darker brown colour of the surface. The ATR-FTIR chemical analysis of the beech wood surface revealed that discolouration was mainly caused by heat-induced processes associated with the degradation of carbonyl groups (C=O) in lignin and hemicelluloses. The splitting of C=O bonds induced changes in the content of chromophores responsible for the natural wood colour and for the engraving-related discolouration. The study demonstrates that the amount of energy supplied onto the wood surface by a laser beam using diverse combinations of radiation parameters can be represented by a single variable: the total irradiation dose. The functional relation detected between this variable and the colour differences may serve as a basis for using a controlled laser beam for targeted wood surface discolouration to improve the quality of patterns transferred onto a wood surface. Knowledge of this relation will enable the targeted setting of the laser parameters during engraving so that the laser beam can be used as a tool for transferring high-quality patterns onto wood surfaces.

Statistical analysis and machine learning-based modelling of kerf width in CO2 laser cutting of PMMA

Statistical analysis and machine learning-based modelling of kerf width in CO2 laser cutting of PMMA

Molybdenum Disulfide/Diselenide-Laser-Induced Graphene-Glycine Oxidase Composite for Electrochemical Sensing of Glyphosate.

The widespread use of the pesticide glyphosate has raised concerns regarding its potential health and environmental impacts. Consequently, there is an increasing demand for monitoring glyphosate levels in surface waters and food products. Currently, there is no commercially available rapid, field-deployable sensor capable of quantifying glyphosate concentrations in environmental samples. This study presents the development of a biosensor based on laser-induced graphene (LIG) that is functionalized with transition metal dichalcogenides (TMDs) and the enzyme glycine oxidase. The LIG is created through a scalable process using a CO2 laser to convert polyimide into a porous, nano/microstructured graphene architecture. The high surface area of LIG acts as a conductive scaffold for subsequent functionalization of both molybdenum disulfide (MoS2) and molybdenum diselenide (MoSe2) to further improve the electroactive surface area of the electrode. The resultant sensors, functionalizesd with the enzyme, demonstrate linear sensing ranges from 10 to 90 μM for glyphosate with detection limits of 4.0 and 6.1 μM for LIG electrodes modified with MoS2 and MoSe2, respectively. Furthermore, the sensors detect glyphosphate at negative working potentials, helping to minimize interference from endogeneous electroactive species and to provide consistent glyphosphate monitoring in actual food products (i.e., soybeans and pinto beans). Overall, the biosensors integrate scalable manufacturing with cost-effective TMDs and LIG, eliminating the need for costly noble metals in the biosensor design, and offering a reliable method for assessing glyphosate in food products.

Hiatal Hernia and Zenker's Diverticulotomy Outcomes

AbstractObjectiveTo compare reflux symptoms, Zenker's diverticulum recurrence, and clinical outcomes in patients with and without a history of hiatal hernia who underwent Zenker's diverticulotomy (ZD).Study DesignSingle institution retrospective review.SettingTertiary care academic hospital.MethodsA retrospective review of patients with and without a history of hiatal hernia who underwent ZD via an open stapler, rigid endoscopic CO2 laser, stapler, or harmonic scalpel technique from January 2006 to December 2020 was performed. Data were abstracted for patient demographics, reflux symptoms, and rates of adverse events and symptomatic recurrence.ResultsA total of 426 patients were included in the study, 97 (22.8%) of which had a history of hiatal hernia. Eleven patients (11.3%) with a history of hiatal hernia had undergone Nissen fundoplication prior to ZD. Patients with a history of hiatal hernia showed less symptomatic improvement postoperatively. Significant differences were noted in the change in the Eating Assessment Tool (EAT‐10) (P &lt; .01) and Reflux Symptom Index (RSI) (P = .03) where patients without a history of hiatal hernia improved more than hiatal hernia patients. Despite these differences in symptom relief, rates of postoperative complications and rates of recurrence did not significantly differ between groups. The median time to recurrence was similar for both groups.ConclusionPatients without a history of hiatal hernia had significantly larger improvements in EAT‐10 and RSI scores compared to patients with a history of hiatal hernia. However, these differences in scores may not represent clinically meaningful differences. There were no significant differences in postoperative adverse events or in recurrence of the Zenker's diverticulum between groups.

Analysis of Kerf Width and its Variation in CO2 Laser Cutting of Straight and Curved Cut Profiles

Analysis of Kerf Width and its Variation in CO2 Laser Cutting of Straight and Curved Cut Profiles

Cutting of 316L stainless steel for metal mesh implant using CO2 laser cutting: Analysis and optimization

This study investigates the effects of CO2 laser cutting parameters on the quality of 316L stainless steel used for metal mesh implants. A Taguchi L9 orthogonal array was employed to design the experiments with three factors: laser power (100-200 W), cutting speed (50-150 mm/min), and gas pressure (3-9 bar). The dimensions (Dim) and heat-affected zone (HAZ) of the cuts were analyzed using both Taguchi and Hybrid Taguchi-Grey Relational Analysis (T-GRA) methods. Results from Taguchi analysis identified the optimal parameters for minimizing Dim as 100 W, 100 mm/min, and 6 bar, and for HAZ as 100 W, 50 mm/min, and 6 bar. ANOVA indicated that laser power significantly influenced both Dim (41.11%) and HAZ (28.10%). T-GRA optimization predicted the optimal parameters as 200 W, 50 mm/min, and 3 bar, confirmed through validation experiments with a Grey Relational Grade (GRG) of 0.969. The study concludes that laser power is the most critical parameter, followed by gas pressure and cutting speed, providing a comprehensive optimization strategy for laser cutting 316L stainless steel for medical implants.

Laser-Induced Graphene Electrodes for Flexible pH Sensors.

In the growing field of personalized medicine, non-invasive wearable devices and sensors are valuable diagnostic tools for the real-time monitoring of physiological and biokinetic signals. Among all the possible multiple (bio)-entities, pH is important in defining health-related biological information, since its variations or alterations can be considered the cause or the effect of disease and disfunction within a biological system. In this work, an innovative (bio)-electrochemical flexible pH sensor was proposed by realizing three electrodes (working, reference, and counter) directly on a polyimide (Kapton) sheet through the implementation of CO2 laser writing, which locally converts the polymeric sheet into a laser-induced graphene material (LIG electrodes), preserving inherent mechanical flexibility of Kapton. A uniform distribution of nanostructured PEDOT:PSS was deposited via ultrasonic spray coating onto an LIG working electrode as the active material for pH sensing. With a pH-sensitive PEDOT coating, this flexible sensor showed good sensitivity defined through a linear Nernstian slope of (75.6 ± 9.1) mV/pH, across a pH range from 1 to 7. We demonstrated the capability to use this flexible pH sensor during dynamic experiments, and thus concluded that this device was suitable to guarantee an immediate response and good repeatability by measuring the same OCP values in correspondence with the same pH applied.

A Comparative Investigation of Kerf Width during CO2 and Fiber Laser Machining of SS 316L Material

Introduction: The unconventional thermal machining method of laser cutting is extensively used. Using this method, any material, essentially, having intricate geometries is machined accurately. The primary purpose of the current paper is to investigate how process factors affect kerf width for CO2 and fiber laser machining of the SS 316L method. This work mainly focuses on an experimental study of CO2 and fiber laser machining for SS 316L. Changing process variables, including gas pressure, laser power, and cutting speed, the cut characteristics are assessed using the measurement of kerf width. A bystronic laser machine is used for the experimentation. Results: The design of the experiment (DOE) technique is applied using the response surface methodology and Box Behnken design. In this, three factors and two levels are chosen, resulting in 17 trial runs. ANOVA is used to perform mathematical computations. This paper also covers the research on SS 316L laser machining and identifies the optimized parameter. The major finding of this research is that changing the laser power affects the kerf width. The CO2 and fiber laser processing results in optimum kerf width values of 0.5726 mm and 0.3950 mm, respectively. Conclusion: This study contributes to the understanding of laser machining of SS 316L and is a valuable resource for potential patent applications related to laser cutting technologies and optimized machining parameters.

Rapid prediction of acute thrombosis via nanoengineered immunosensors with unsupervised clustering for multiple circulating biomarkers.

The recent SARS-CoV-2 pandemic underscores the need for rapid and accurate prediction of clinical thrombotic events. Here, we developed nanoengineered multichannel immunosensors for rapid detection of circulating biomarkers associated with thrombosis, including C-reactive protein (CRP), calprotectin, soluble platelet selectin (sP-selectin), and D-dimer. We fabricated the immunosensors using fiber laser engraving of carbon nanotubes and CO2 laser cutting of microfluidic channels, along with the electrochemical deposition of gold nanoparticles to conjugate with biomarker-specific aptamers and antibody. Using unsupervised clustering based on four biomarker concentrations, we predicted thrombotic events in 49 of 53 patients. The four-biomarker combination yielded an area under the receiver operating characteristic curve (AUC) of 0.95, demonstrating high sensitivity and specificity for acute thrombosis prediction compared to the AUC values for individual biomarkers: CRP (0.773), calprotectin (0.711), sP-selectin (0.683), and D-dimer (0.739). Thus, a nanoengineered multichannel platform with unsupervised clustering provides accurate and efficient methods for predicting thrombosis, guiding personalized medicine.

Integrating CO2 lasers in dental education: Addressing safety, compliance, and curriculum.

Integrating CO2 lasers in dental education: Addressing safety, compliance, and curriculum.

Bowen’s disease mimicking lichen simplex chronicus in a 56-year-old Filipino man: A case report

Background: Bowen's disease (BD) is a chronic skin condition presenting clinically as erythematous plaques with scales on sun-exposed areas. BD is generally regarded as a squamous cell carcinoma (SCC) in situ. In contrast, lichen simplex chronicus (LSC), also known as neurodermatitis, is a chronic skin disorder characterized by extreme pruritus. In LSC, lichenified plaques form primarily on accessible body parts due to repeated scratching or rubbing. Case Illustration: A 56-year-old male presented with a solitary chronic plaque with a central ulcer and erosions on his left upper thigh. Dermoscopy findings were glomerular vessels and a scaly surface, which are typical features of BD. A skin punch biopsy showed numerous atypical keratinocytes with mitotic figures in the epidermis, which is also typical of BD. The patient underwent carbon dioxide (CO2) laser treatment in our institution. Discussion: The natural course of LSC and BD is usually prolonged, and their similarities in clinical presentation require appropriate examination. Dermoscopy findings and histopathology results may help determine the precise diagnosis and appropriate treatment. Conclusion: BD lesions can mimic LSC; therefore, histopathology examination is the gold-standard to establish the diagnosis of BD. Careful and precise examination should be done to distinguish the similarities between LSC and BD.

Tunable Infrared Emissivity Using Laser‐Sintered Liquid Metal Nanoparticle Films

AbstractThis paper describes laser exposure to tune the infrared (IR) emissivity of a film of eutectic gallium indium (EGaIn) particles. EGaIn – a liquid metal at room temperature – forms a native oxide that keeps particles of the metal from spontaneously percolating. Photothermal energy from a CO2 laser percolates the particles into a conductive network. Here, it also causes a decrease in the IR emissivity of the film of particles from 0.4 to 0.24 over the range of 7.5–13 µm wavelength (measured by an IR camera) with the increase of laser fluence from 1.4 to 1.9 J cm−2. The particles percolate most prominently at the bottom of the film, and thus, the apparent surface roughness does not change with laser exposure. This finding suggests the decrease in emissivity is not due to changes in the film's topography. Instead, the change in IR emissivity is attributed to a loss of the surface plasmonic resonance effect of EGaIn particles in the IR range after the sintering, which is confirmed by optical simulations. As a demonstration, it is shown that the ability to change the emissivity makes it possible to encrypt messages and camouflage laser‐processed patterns.

Comparison of Q-Switched Nd:YAG LASER with 10% Azelaic Acid versus Fractional CO2 LASER with 10% Azelaic Acid in the treatment of Post Inflammatory Hyperpigmentation secondary to Acne

Background:Post inflammatory hyperpigmentation (PIH) secondary to acne is a common undesirable sequela following acne that leads to psychological distress and a sense of incomplete treatment among the patients with acne. Few studies have been done in regard to address this condition, and no definite treatment or clear ranking of treatment modalities is available as of yet.Aims:The aim of our study was to assess and compare the efficacy and safety of 1,064-nm Q-switched neodymium-doped yttrium aluminum garnet (QSNY) laser with 10% azelaic acid versus Fractional carbon dioxide (FCO2) laser with 10% azelaic acid in the treatment of post acne pigmentation.Materials and Methods:Seventy patients with PIH secondary to acne were recruited in this study. The patients were randomized into two groups, Group A and Group B, of thirty-five patients each. Patients in group A underwent QSNY laser, while Group B received FCO2 laser. 10% azelaic acid cream was administered to both groups. Both groups received a total of 5 treatment sessions, with 3 weeks interval between each setting. The efficacy and safety of both modalities were assessed using the quartile grading score(QGS), post acne hyperpigmentationindex(PAHPI), patient satisfaction score, and documentation of adverse effects.Results:At the end of five sessions, significant improvement in QGS, PAHPI and patient satisfaction (P &lt; 0.001, respectively) was seen in both groups. The mean PAHPI significantly reduced after the third setting and was followed by drastic reduction in the following settings. However, significantly superior results were noted in Group A with respect to all assessments. Side effects noted were mild and transient, except two patients of Group B who developed further pigmentation over the treatment areas.Conclusion:This study shows that both QSNY laser and FCO2 laser can be used to treat post-acne pigmentation; however, QSNY laser should be preferred with respect to efficacy and safety, especially in the Indian population, owing to the higher risk of pigmentation following FCO2 laser.