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Understanding Film-to-Stripe Transition of Conjugated Polymers Driven by Meniscus Instability
摘要： Meniscus instability during meniscus-guided solution coating and printing of conjugated polymers has significant impact on the deposit morphology and the charge transport characteristics. The lack of quantitative investigation on meniscus-instability-induced morphology transition for conjugated polymers hindered the ability to precisely control conjugated polymer deposition for desired applications. Herein, we report a film-to-stripe morphology transition caused by stick-and-slip meniscus instability during solution coating seen in multiple donor-acceptor polymer systems. We observe the coexistence of film and stripe morphologies at the critical coating speed. Surprisingly, higher charge carrier mobility is measured in transistors fabricated from stripes despite their same deposition condition as the films at the critical speed. To understand the origin of the morphology transition, we further construct a generalizable surface free energy model to validate the hypothesis that the morphology transition occurs to minimize the system surface free energy. As the system surface free energy varies during a stick-and-slip cycle, we focus on evaluating the maximum surface free energy at a given condition, which corresponds to the sticking state right before slipping. Indeed, we observe increase of the maximum system surface free energy with increase in coating speed prior to film-to-stripe morphology transition and abrupt drop in the maximum system surface free energy post-transition when the coating speed is further increased, which is associated with reduced meniscus length during stripe deposition. Such energetic change originates from the competition between pinning and depinning forces on a partial wetting substrate which underpins the film-to-stripe transition. This work establishes a quantitative approach for understanding meniscus-instability-induced morphology transition during solution coating. The mechanistic understanding may further facilitate the use of meniscus instability for lithography-free patterning or to suppress instability for highly homogeneous thin film deposition.
关键词： conjugated polymer,meniscus instability,printed electronics,morphology transition,solution coating
更新于2025-09-23 15:21:21
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Meniscus Shape Control Using Electrowetting and Its Application to Optical Devices
摘要： Electrowetting is a technique to modify wettability and meniscus shapes on electrodes by applying voltage to the electrodes. In the present article, we introduce principles of electrowetting deriving the equation connecting voltage and contact angle. Then we reviews related articles on optical devices using electrowetting including our previous works; a liquid prism controlling optic-axis using electrowetting. Numerical simulation solved meniscus shapes between each liquid to predict the relation between applied voltage and optic angle. Results in experiments and simulations are briefly reported.
关键词： Meniscus,Electrowetting,Numerical simulation,Optical devices,Wetting
更新于2025-09-23 15:21:21
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Maturation of the Meniscal Collagen Structure Revealed by Polarization-Resolved and Directional Second Harmonic Generation Microscopy
摘要： We report polarization-resolved Second Harmonic Generation (p-SHG) and directional SHG (forward and backward, F/B) measurements of equine foetal and adult collagen in meniscus, over large field-of-views using sample-scanning. Large differences of collagen structure and fibril orientation with maturation are revealed, validating the potential for this novel methodology to track such changes in meniscal structure. The foetal menisci had a non-organized and more random collagen fibrillar structure when compared with adult using P-SHG. For the latter, clusters of homogeneous fibril orientation (inter-fibrillar areas) were revealed, separated by thick fibers. F/B SHG showed numerous different features in adults notably, in thick fibers compared to interfibrillar areas, unlike foetal menisci that showed similar patterns for both directions. This work confirms previous studies and improves the understanding of meniscal collagen structure and its maturation, and makes f/B and p-SHG good candidates for future studies aiming at revealing structural modifications to meniscus due to pathologies.
关键词： Second Harmonic Generation,meniscus,directional SHG,polarization-resolved,collagen
更新于2025-09-23 15:21:01
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[ASME ASME 2018 13th International Manufacturing Science and Engineering Conference - College Station, Texas, USA (Monday 18 June 2018)] Volume 1: Additive Manufacturing; Bio and Sustainable Manufacturing - High-Throughput 3D Printing of Customized Imaging Lenses
摘要： The emerging 3D printing technology has the potential to transform manufacturing customized optical elements, which currently heavily relies on the time-consuming and costly polishing and grinding processes. However, the inherent speed-accuracy trade-off seriously constraints the practical applications of 3D printing technology in optical realm. In addressing this issue, here, we report a new method featuring a significantly faster fabrication speed, at 24.54 mm3/h, without compromising the fabrication accuracy or surface finish required to 3D-print customized optical components. We demonstrated a high-speed 3D printing process with deep subwavelength (sub-10 nm) surface roughness by employing the projection micro-stereolithography process and the synergistic effects from the grayscale photopolymerization and the meniscus equilibrium post-curing methods. Fabricating a customized aspheric lens with 5 mm in height and 3 mm in diameter could be accomplished in less than four hours. The 3D-printed singlet aspheric lens demonstrated a maximal imaging resolution of 2.19 μm with low field distortion less than 0.13% across a 2-mm field of view. This work demonstrates the potential of 3D printing for rapid manufacturing of optical components.
关键词： optical lenses,meniscus equilibrium post-curing,projection micro-stereolithography,3D printing,grayscale photopolymerization
更新于2025-09-23 15:21:01
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Evaluation of tear meniscus dimensions using anterior segment optical coherence tomography in video terminal display workers
摘要： Background: To evaluate tear meniscus height and tear meniscus area measured by optical coherence tomography (OCT) and to determine the prevalence of dry eye disease in video display terminal (VDT) users. Methods: This was a case–control study performed on VDT users. The case group consisted of 53 subjects who vocationally use VDT more than six hours per day and the control group consisted of 49 subjects who used VDT not more than one hour per day. The pre-vocational and post-vocational tear meniscus height and tear meniscus area measurements were performed twice in one day using OCT. Tear-film break-up time, Schirmer’s test, Ocular Surface Disease Index score and corneal staining score measurements were performed in all subjects. Results: The mean age was 38.9 (cid:1) 5.5 years in VDT users and 37.8 (cid:1) 5.8 years in the control group (p = 0.426). Twenty patients (37.7 per cent) had dry eye disease in VDT users and five patients (10.2 per cent) had dry eye disease in the control group (p = 0.001). The mean tear meniscus height and tear meniscus area values (pre-vocational and post-vocational) were significantly lower in VDT users than in the control group (p < 0.001, p < 0.001, p = 0.024 and p < 0.001, respectively). The Schirmer’s test results, Ocular Surface Disease Index scores, corneal staining scores and tear-film break-up time values revealed significant differences between VDT users and control subjects (p = 0.002, p = 0.006, p < 0.001 and p < 0.001, respectively). In addition, significant correlations were demonstrated between Schirmer’s test results, Ocular Surface Disease Index scores, corneal staining scores, tear-film break-up time measurements, tear meniscus height results and tear meniscus area values. Conclusion: Tear meniscus evaluation using OCT is an effective, non-invasive and sensitive method for detection of dry eye disease in VDT users.
关键词： dry eye disease,tear meniscus height,video display terminal,optical coherence tomography,tear meniscus area
更新于2025-09-19 17:15:36