Laser-based mass production of micro structures may not be suitable in many cases because it is a serial process: devices are fabricated one by one only. Replication techniques for fabricating nano/micro structures have been investigated and developed for a long time and in our work, we present replicating micro structures in polymers using laser fabricated glass-ceramic stamps. A micro stamping process applying heat and pressure, also referred to as hot embossing, can replicate micro structures on polymer surfaces. By reforming thermoplastics, micro features can be transferred to polymer surfaces. Hot embossing normally employs metal and or silicon stamps. In this work, we use a glass-ceramic stamp which can be easily and quickly fabricated with a laser-based pattern transferring technique. In addition, a micro stamping device has been designed and developed for this process. Many micro structures such as micro channels, capillaries, and micro diffusers are produced and the advantages of this process are discussed.
Recently much research on fabrication of polymer micro structures has been carried out. One of the main advantages of using polymer in micro structure fabrication is the easiness of applying replication processes for mass production. A micro stamping process applying heat and pressure, also referred to as hot embossing lithography, can replicate micro-structures on polymer surfaces. By reforming thermoplastics, many micro features can be transferred directly to polymer surfaces. The micro stamping consists of two main steps: a stamp fabrication step and a replication step. Until now, metal or silicon stamps have been used. In this work, photo-etchable glass-ceramic micro stamps are used, which are micro-machined using an excimer laser processing technique. With the laser process, a glass-ceramic stamp can be fabricated quickly and precisely. In addition, a micro stamping device has been designed and developed for this process. Polyvinylchloride (PVC) is used as the replicating polymer because it has a low glass transition temperature (65 C) and good formability. Many micro structures such as micro channels have been produced. The advantages and the limits of using glass-ceramics stamps and stamping with the PVC material are discussed.
We discuss laser fabrication of microstructures in photoetchable glass ceramics called Foturan (Schott Company, Elmsford, NY). A KrF excimer laser (= 248 nm, = 25 ns) is used for surface micromachining, and a femtosecond laser (= 800 nm, = 80 fs) is used for fabricating 3-D structures. Important aspects of the machining, such as depth of machining resulting from different laser processing parameters and threshold laser fluences, are presented. A detailed analysis of the absorption process of both lasers in photoetchable glass ceramics is provided.
Diffuser micropumps are commonly fabricated using the standard lithography techniques with silicon as the base material. The important components of this type of micropumps are flow-directing diffusers and a moving diaphragm. Different diffuser designs show various flow rates and pump efficiency. In this work a polymer is used as the base material instead of silicon. It is demonstrated that polymer-based micropumps can be conveniently fabricated using the laser machining technique. Moreover, because of the flexibility of polymer materials, there is great potential to improve the performance of the polymer micropumps. The fluid flow inside the diffuser polymer micropump is also calculated using computational fluid dynamics methods and the simulated results are compared with the experimental data.
We discuss laser fabrication of microstructures in photoetchable glass-ceramics, FOTURAN. A KrF excimer laser (λ = 248 nm, τ = 25 ns) is used for surface micromachining, and a femtosecond laser (λ = 800 nm, τ = 80 fs) is used for fabricating three-dimensional structures. Other aspects of the machining, such as the fluence and crystallization depth resulting from these two methods are presented. A detailed analysis of the absorption process of both lasers in FOTURAN is discussed.
Diffuser micro-pumps are commonly fabricated with the standard lithography techniques using silicon as the base material. The important components of this kind of micro-pump are flow directing diffusers and a moving diaphragm. Different diffuser designs show various flow rates and pump efficiency. In this work, polymer is used as its base material instead of silicon. Polymer is cost-effective and relatively easy to be machined with an Excimer laser. Moreover, the flexibility of the material gives a much better performance compared with the silicon based micro-pumps. The measured flow rate of this pump is 10 to 20 times higher than that of the silicon based micro-pumps. In addition, the performance of the diffuser polymer micro-pump is simulated with FLUENT and the calculated result at low frequency is in good agreement with the experimental result.
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