Microfluidics Core Facility Equipment for the production and validation of microfluidic chips

By using photolithography, we can generate the mold (Masterwafer) on a silicon wafer coated with photoresist. The Mask-less Aligner is our instrument of choice, because it makes the use of chrome masks redundant and allows us to generate a high number of Masterwafers in a relatively short amount of time. The resolution of the instrument is in the range between 1µm to 200µm in z-direction, and the smallest feature in x-y is 1x1µm.  Additionally to 2D microfluidic chips, it is possible to generate double-layer microfluidic wafers. They have the advantage of different heights incorporated in the same chip design. This instrument is used to make wafers for droplet-based microfluidic experiments, continuous-flow experiments or molds for cell migration microchannels.

Droplet-based MicrofluidicsContinuous Flow Experiments Microchannel Devices

The BMF microArch S140 is a precise digital light projection (DLP) printer with a layer thickness of 10µm. With the addition of the 3D printer, we can cover a bigger size range in preparing microfluidic devices. With a smallest resolution of 10µm, the printer allows for very fine feature sizes up to 14mm in height. Besides microfluidic devices, we are also using this instrument to prepare scaffolds or molds for different applications. Currently we have a biocompatible and a hard material resin available in the facility. On demand from the user, different resins can be purchased from the company by the µFlu CF. The printer also allows the usage of custom-made resins. Several applications are listed on the page 3D printing services.

3D Printing Service

To fabricate PDMS-based microfluidic device bonded to glass slides we make use of an oxygen plasma (TePla, GigaBatch 310M). With a power of 600W, our instrument is very powerful and can also be used for a variety of different applications. 

Plasma treatment for Biomedical Applications. Interfaces treated with plasma can affect biological organisms either directly or indirectly. It was shown that during the process of oxygen plasma, Reactive Oxygen Species (ROS) are generated which etch the membrane of bacterial or cancer cells and thereby induce apoptosis of the organisms. This process is considered as direct plasma treatment for the sterilization of various substrates or in-depth cancer treatment. Examples for indirect interfaces are for example the anti-microbial effects of surfaces such as medical devices. It was shown that after plasma treatment, the molecular layer on the substrates is crosslinked, generating a barrier on the surface for microbe migration and adhesion. Besides sterilization and induced cell apoptosis using plasma, the treatment of surfaces is also used to improve cell adhesion. By adding functional groups to the surfaces which are interacting with organisms, an indirect interaction is facilitated. Hereby, it is possible to increase the adhesion capabilities of 3D printed surfaces for tissue engineering constructs or the investigation of cellular behavior within 3D environment.

After generating a Masterwafer (described under Mask-less Aligner (Heidelberg Instruments, µMLA)) it is crucial to measure the height of the generated structure. By using the interference profilometer we can precisely measure the height difference between silicon wafer and the exposed photoresist. The detection range is from 1µm up to 2-3mm.

We use the AxioLab5 upright microscope to control the quality of our fabricated devices.