Laser cutting: "We can use the laser to produce component geometry sizes of 5 to 50 micrometers"

Micro seals or tiny microfluidic channels – COMPAMED trade fair visitors know how fascinating such tiny elements can be. Often invisible to the naked eye, these components are structured in the micrometer range. In this COMPAMED-tradefair.com interview, M.Sc.Eng. Volker Franke from the Fraunhofer IWS explains how this concept works and reveals the advantages a laser offers in this setting.

Mr. Franke, you study the micro- and fine processing of functional elements at the Fraunhofer IWS. What are you currently working on and how does your research on functional components affect medical technology?

Volker Franke: We have been developing production processes based on laser applications for our industry and research partners for many years. We use the laser as a tool to facilitate high-precision processing of a wide variety of materials. This ranges from drilling micrometer-sized holes, such as those needed in specific nozzle arrangements, to drilling a large number of holes to prepare foils, for example. The latter are important for filter applications or when microphysiological systems require permeability. We also explore the damage-free cutting of any material. This includes cutting of elastomer foils to facilitate high-precision production of micro seals used in many medical devices.

We also study the functionalization of surfaces. To this effect, we fabricate micrometer-sized structures in a targeted manner to alter specific functional properties. As such, we were able to show that slight textures in the surface can affect the proliferation of cells or bacteria. This is an interesting aspect as it pertains to dental implants, for example.

Can the laser technique also be used for other medical device production processes?

Franke: The process is also suitable to clean the surfaces of components. When it comes to medical device production, it is applied in intermediate steps or in the final cleaning process of the product. It is also used where conventional cleaning processes that are based on different cleaning agents are not an option. Another application pertains to components that require localized cleaning of functional areas versus cleaning of the overall component.

You also use laser micro cutting to produce microfluidics for Lab-on-a-Chip systems. How does this work?

Franke: There are different strategies and methods you can use. The most commonly used approach involves milling or cutting out trenches or channels from a material. This volume ablation creates channel surface structures. We developed an alternative process at the Fraunhofer IWS and use the laser as a cutting tool to separate thin plastic foils from application-adapted materials. We achieve this by cutting channel structures into the individual layers of plastic. In the next step, the foils are stacked on top of each other to facilitate the easy and flexible production of complex and even three-dimensional microfluidic systems. This process allows freedom as it pertains to the design and configuration of these systems. What’s more, it is also much faster than volume ablation, making the technique very efficient in the overall process chain. One can even call this a high-throughput technology that enables us to produce both individual microfluidic chips and larger quantities with different structure geometries or designs.

What are the orders of magnitude when it comes to microprocessing?

Franke: We can use the laser to produce component geometry sizes of 5 to 50 micrometers and larger if required. In some instances, we create even smaller structures with targets of two to three micrometers as it always depends on the application and the respective material. Pulsed lasers facilitate gradual material ablation, allowing you to adjust the depth of structures in the sub-micrometer range. For example, it’s possible to achieve a depth of 0.1 microns for materials from which coatings must be removed.

What solutions do your clients from the medical technology sector typically want from you?

Franke: Our industry or research partners often approach us when conventional production processes have reached their limits. This applies to new product developments that use new materials, for example. That’s when the laser can be a potential solution. Our partners also inquire about functional surfaces and their various applications. In this setting, users are interested in hydrophobic or hydrophilic properties, as well as in friction and wear resistance of interacting surfaces or components. We get many requests in this specific area.