High speed laser drilling of precise micro and nano holes in metallic surface filters

T. Barthels*, H. Westergerling, M. Reininghaus, Fraunhofer Institute for Laser Technology ILT, Germany

In the field of micro and nano structuring, ultrashort pulse (USP) laser material processing with a multibeam approach is attracting increasing attention due to its ability to generate periodic patterns with high throughput (up to 12.000 holes/sec). A wide range of applications exists for the generated structures, e.g. functional structures for the automotive industry, consumer electronics but also for filtration technology. USP laser with a pulse duration of several 100 femtoseconds are already commercially available today and are suitable for the generation of precise structures in various metals in the micrometer and sub-micrometer range. The multibeamscanner (MBS) developed at the Fraunhofer ILT enables laser processing with more than 200 beams in parallel and a precision < 1 µm. The MBS offers the potential to provide filter membranes of stainless steel foils with sub-micrometer-sized holes over a large area. The production technology is suitable for manufacturing regenerative microfilters for industrial applications in the fields of biotechnology, pharmacy and medical technology.

Application for high precision surface filter inserts

For more than ten years, the Fraunhofer ILT has been active in the field of high-precision structuring of metal foils using USP laser systems. Metal foils with thicknesses from 5 µm to 100 µm are commercially available with holes sizes down to the lower single-digit micrometer exit diameter.

Microplastics and pathogens: The surface filter cartridges are currently being developed to filter microplastic particles of >10 µm out of wastewater. Microplastics are the smallest plastic particles with a diameter of <5 mm [1], which are either deliberately used in a wide variety of products or are caused by natural abrasion and erosion. Synthetic micropolymer particles, which are referred to as primary microplastics, serve in many hygiene products as peeling particles, binders or fillers and enter after the use of the product the water cycle and thus in our food chain [2]. In addition to the social interest of water pollution by microplastics, the pollution of water by bacteria and multi-resistant pathogens is becoming more and more important for our society [3]. Using suitable USP laser and the patented multibeamscanner, the Fraunhofer ILT develops a technology for drilling holes with sub-micrometer size in stainless steel foils at a pitch distance of a few micrometers. The surface filter inserts designed for the filtration of microplastics can also be used to filter pathogens by further reducing the hole diameter...

Session: F3 - Advanced Filter Media Developments and Manufacturing Methods
Day: 22 October 2019
Time: 16:45 - 18:00 h

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