Fabrication of microfilters using excimer laser micromachining and testing of pressure drop

Abstract

The excimer laser micromachining process has displayed numerous advantages as an efficient tool for fabricating 2D and 3D micro-components, such as a high-resolution power (up to sub-micrometer range) and ablation without thermal damage. This work investigates the suitability and limitations of the process for the fabrication of microfilters using excimer laser micromachining. Their successful fabrication requires precise control over the work parameters, and deals with a number of challenges. Three microfilters of mean pore sizes 14.4 µm, 18.3 µm and 25.6 µm but with the same opening ratio, and containing up to 14 000 holes, have been fabricated. Their performance has been assessed by measuring air flow, to capture a trend in pressure drop induced by the filter for varying flow rates. The Reynolds number based on hole diameter covered is 0.0086–0.21. The key findings include development of a successful method of fabrication, a positive correlation between pressure drop and flow rate during testing, and an increase in slope of the pressure curve with a decrease in pore size. The correlation available in the literature shows a large deviation with respect to the experimental data and a new correlation has been proposed. These results are expected to help design microfilters in the very low Reynolds number range.