Abstract

High Aspect Ratio Structures in Microfluidic Channels by UV-Nanoimprint Lithography

Daniel Borstner, scientist, Joanneum Research Forschungsgesellschaft mbH

The integration of high aspect ratio (HAR) structures in a microfluidic channel can increase the surface area significantly, which is beneficial for, e.g., medical diagnostics. Direct fabrication methods such as plasma or wet chemical etching are resource, time and cost consuming and therefore less suitable for point of care application. We report master design by optimized photolithography and upscaling by cost effective UV-nanoimprint lithography to pave the way for single use chip fabrication. Standard photolithographic routines are optimized with focus on HAR and subsequent UV-NIL upscaling. Depending on the structure, geometry and channel depth positive or negative resist mastering processes were developed for microstructure filled channels with aspect ratios ranging from 1 to 4. Replication of such HAR masters is challenging by incomplete resin filling, adhesion and breaking elements. To overcome these issues specific routines including resin development, metallization and surface functionalization approaches are employed to facilitate demolding. The reported process chains enable comprehensive lab scale investigation of HAR microstructured microfluidic chips with the possibility of high throughput roll-to-toll UV-NIL upscaling [1].