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Easy-to-operate fabrication of tapered glass capillaries for microdroplet generations
摘要： Tapered glass capillaries play an important role in micro droplets generation and related micro?uidic applications such as particle synthesis, digital PCR, microrectors. However, its controlled production poses a challenge. Speci?cally, there is di?culty controlling the tip sizes of capillaries with good repeatability at an a?ordable cost, which is critical to producing standard droplets for use by research groups. To produce tapered capillaries, micro needle geometries are ?rst pulled by commercial pipette puller, which yields a sharp tip (i.e. 1-3μm). Those tips need to be enlarged and standardized by post microfabrication. Although larger tips could be achieved by advanced pulling-forging, sanding-forging or breaking-forging methods, the uniformity and repeatability do not meet the requirements for mass production. In this paper, several easy-to-operate fabrication approaches, including mechanical and chemical fabrication methods, are studied. Chemical etching fabrication method shows good repeatability and robust control of dimensions. A capillary droplet micro?uidic device assembled by tapered glass capillaries fabricated by chemical etching method is also presented, which shows good performance for droplet generations. This non-labor intensive fabrication is straightforward and be readily adopted for industrial scale mass production.
关键词： glass capillary,micro fabrication,taper,droplet generation
更新于2025-09-23 15:22:29
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Implementation and assessment of a low-cost 3D laser platform controlled by open software for printing polymeric micro-structures
摘要： A low-cost 3D opto-mechatronic platform controlled by free-source software with optical and mechanical resolutions of 120 μm and 10 μm, respectively, was developed to fabricate micro-pedestals in grid presentation and diffractive optical elements such as micro-square and micro-slits. Direct laser writing (DLW) and low-one photon absorption (LOPA) were employed as the fabrication protocol and the physical phenomena involved in the platform control and development of the micrometric structures. A laser pointer, one of the lowest-cost lasers in the market, centered at 532 nm with an intensity of 65 mW, was used to polymerize the SU8-2050 photoresist through the DLW procedures. The printing process was carried out by using a 5X and 10X microscope objectives with numerical apertures of 0.13 and 0.25, respectively. The point spread function demonstrated the geometrical variations and the field intensity distribution about the focal plane, where the Debye-Wolf approximation is valid, which were used for comparison purposes. Ray tracing simulations were in addition presented demonstrating how light interacts with the SU8-film and how out of focus condition plays a fundamental role in the final size of the printed micro-pattern. Finally, two optical diffractive elements and their diffraction patterns in the Fraunhofer regime were presented.
关键词： low-one photon absorption,micro-fabrication,direct laser writing,optical diffraction
更新于2025-09-19 17:13:59
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Micro-fabricated wideband band-stop filter using GaAs-based integrated passive device technology
摘要： This paper presents a new concept of implementing a micro-fabricated wideband band-stop filter on a gallium arsenide (GaAs) substrate using integrated passive device technology. The incorporation of an air-bridge structure was explored to enhance design flexibility and achieve excellent radio-frequency performance of the filter. A wideband band-stop filter was realized on a GaAs substrate, generating an insertion loss of ? 0.37 dB and a return loss of ? 38 dB with excellent attenuation of ? 28.78 and ? 22.27 dB, in the lower and the upper passband, respectively. The filter resonates at 10.72 GHz, occupying a die area of 2000 μm × 1540 μm. The selectivity of the filter is reflected by its tremendous suppression of out-of-band signals with the existence of attenuation poles in the vicinity of the resonance frequency. Experimental verification of the filter response demonstrates its potential use as an on-chip device operating in the X-band frequency spectrum.
关键词： Gallium arsenide (GaAs),Wideband band-stop filter,Radio frequency (RF),Integrated passive device technology,Micro-fabrication
更新于2025-09-04 15:30:14