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![SEM images of the PEG-DA pillars fabricated using 95 fs laser pulses and five beam configuration with exposure density dosages of (a) 6.9, (b) 20.8; 27.8; and 104.2 J/cm 2 . The insert in (a) shows the calculated intensity distribution of the interference pattern using Eq. 2. Tilt: 30º [28].](profile/Andres-Lasagni/publication/228450495/figure/fig5/AS:393739878060035@1470886310468/SEM-images-of-the-PEG-DA-pillars-fabricated-using-95-fs-laser-pulses-and-five-beam.png)
SEM images of the PEG-DA pillars fabricated using 95 fs laser pulses and five beam configuration with exposure density dosages of (a) 6.9, (b) 20.8; 27.8; and 104.2 J/cm 2 . The insert in (a) shows the calculated intensity distribution of the interference pattern using Eq. 2. Tilt: 30º [28].
Source publication
We report on fabrication of periodic arrays of polyethylene glycol diacrylate (PEG-DA), a biocompatible hydrogel, useful in biomedical applications. The structures were produced by means of multi beam laser interference lithography with both nanosecond (266 and 355 nm of wavelengths with pulses lasting 10 ns) and femtosecond pulsed lasers (800 nm o...
Contexts in source publication
Context 1
... another set of experiments, we used a five beam configuration to fabricate the periodic structures on pre-and post- baked samples (see experimental part). At low exposure doses, we were able to fabricate pillars with heights of 2.5 ± 0.1 and 3.6 ± 0.1 µm for 6.9 and 20.8 J/cm 2 of exposure doses, respectively (Figure 5a and b). In contrast with the four beam configuration (Figure 4), the intensity between two consecutive maxima does not decrease to zero and consequently the pillars can be laterally cross-linked when utilizing higher exposure doses (Figure 5c and d). ...
Context 2
... low exposure doses, we were able to fabricate pillars with heights of 2.5 ± 0.1 and 3.6 ± 0.1 µm for 6.9 and 20.8 J/cm 2 of exposure doses, respectively (Figure 5a and b). In contrast with the four beam configuration (Figure 4), the intensity between two consecutive maxima does not decrease to zero and consequently the pillars can be laterally cross-linked when utilizing higher exposure doses (Figure 5c and d). In this manner, high stable 2pm j hydrogel pillar structures with lateral interconnectivity could be fabricated. ...
Citations
... For more efficient use of the exciting laser radiation, it is necessary to produce a periodic intensity distribution as shown in Fig. 1. In the technologies of micro-and nanostructuring of surfaces, this is done by using microlens arrays [6], holographic optical elements [7], or interference of two or more beams [8]. ...
A new method for generating terahertz radiation by exposure to femtosecond laser pulses on the semiconductor surface is proposed. The essence of this method is that the exciting radiation intensity is subjected to spatial modulation by using a microlens array and by shading a part of the semiconductor surface by metal stripes. This gives rise to a concentration gradient of photo carriers along the surface at the sharp boundary of the metallic coating in the semiconductor (transverse Dember photoelectric effect), and its relaxation for times of ∼1 ps results in the emission of electromagnetic pulses of the terahertz range. A terahertz emitter model based on the proposed method was developed and designed, its efficiency was demonstrated, and methods for increasing its efficiency were considered.
... Two decades later, multiple MBIL exposures were proposed to generate more complex 2D patterns in a photoresist [138]. Since then, a wide range of structures have been recorded via MBIL using near-infrared [129,139140141142, visible light [18,31,32,62,88,143144145146147148149150151152153, ultraviolet (UV) [62,77,78,99,115,154155156157158159160, deep-UV [92,101,142,161162163, and extreme-UV sources164165166167. Today, MBIL is considered a potentially key enabling technology for the ever-increasing demand for smaller feature sizes in optical lithography [4,131,168]. ...
... Two decades later, multiple MBIL exposures were proposed to generate more complex 2D patterns in a photoresist [138]. Since then, a wide range of structures have been recorded via MBIL using near-infrared [129,139140141142, visible light [18,31,32,62,88,143144145146147148149150151152153, ultraviolet (UV) [62,77,78,99,115,154155156157158159160, deep-UV [92,101,142,161162163, and extreme-UV sources164165166167. Today, MBIL is considered a potentially key enabling technology for the ever-increasing demand for smaller feature sizes in optical lithography [4,131,168]. ...
Research in recent years has greatly advanced the understanding and capabilities of multi-beam interference (MBI). With this technology it is now possible to generate a wide range of one-, two-, and three-dimensional periodic optical-intensity distributions at the micro-and nano-scale over a large length/area/volume. These patterns may be used directly or recorded in photo-sensitive materials using multi-beam interference lithography (MBIL) to accomplish subwavelength patterning. Advances in MBI and MBIL and a very wide range of applications areas including nano-electronics, photonic crystals, metamaterials, subwavelength structures, optical trapping, and biomedical structures are reviewed and put into a unified perspective.
Some fluorescence microscopy techniques, like confocal laser scanning microscopy (CLSM), have a limited penetration depth. Consequently, the visualization and imaging of 3D cell cultures, such as spheroids, using these methods can be a significant challenge. Therefore, to improve the imaging of 3D tissues, optical clearing methods have been optimized to render transparency to the opaque spheroids. In this work, the influence of the polyethylene glycol (PEG) molecular weight (MW) used in the ClearT2 16 method for the imaging of propidium iodide (PI) stained spheroids was investigated. The results demonstrated that the ClearT2 clearing method contributes to spheroids transparency and to the preservation of PI fluorescence intensity for all the PEG MW used
(4000, 8000 and 10000 Da). Further, the ClearT2 method performed using PEG 4000 Da allowed a better PI signal penetration depth and cross-section depth. Overall, the optimization of PEG MW can improve the imaging of intact spheroids by CLSM. Further, this work may also contribute to increase the application of 3D cell culture models
by the pharmaceutical industry for the high-throughput screening of therapeutics.
