Novel fabrication approaches
Our sensors and sensor arrays are fabricated using novel additive technologies. These allow a flexible process management, as well as the use of polymeric and biocompatible materials. Our fabrication methods are mainly based on ink-jet aerosol-jet and capillary printing, as well as stereolithographic 3D printing.
Inkjet printing in microfabrication
In inkjet printing, a piezo actuator accelerates individual drops of inks towards the substrate. In regular printing, these inks transport pigments or dyes onto the paper. Using the same principle, however, polymer solutions or metal nanoparticle suspensions can be printed to define functional structures such as conductors or dielectrics. In this way, modern inkjet printers are capable of fabricating electronic components with a resolution in the micrometer regime. In comparison to classical microfabrication, this bears advantages regarding process flexibility and material choice.
Capillary plotting for high-viscosity inks
Apart from inkjet printing, we use capillary plotting in the fabrication of our sensors. In capillary plotting, an ink-filled glass microcapillary is brought into close proximity with the substrate. The capillary is then actuated with an oscillating Piezo crystal. Using functional inks, this process can be used to plot functional structures. Similar to inkjet printing, this process can be done using, for instance, polymer solutions or metal nanoparticle suspensions. One advantage of this technique compared to inkjet printing is its compatibility with high viscosity inks. In addition, the plotter can be operated using vector-based data in contrast to pixel-based data as is the case for inkjet printing. In particular in the generation of rounded shapes, this leads to fewer artifacts.
Both of the above described processes are mainly able to define functional elements such as conductors or electrodes. In order to generate 3-dimensional geometries like, for instance, microfluidics or structured cell culture substrates, we make use of stereolithographic 3D-printers. In stereolithogrpahic 3D-printing, the desired structure is produced layer-by-layer from a photo-sensitive resin. Similar to the advantages of inkjet printing and capillary plotting, this technique requires only little effort to implement changes to the model.