Confined Gelatin Dehydration as a Viable Route To Go Beyond Micromilling Resolution and Miniaturize Biological Assays

Nowadays, microfluidic channels of a few tens of micrometers are required and widely used in many fields, especially for surface-processing applications and miniaturization of biological assays. Herein, we selected micromilling as a low-cost technology and proposed an approach capable of overcoming its limitations; in fact, microstructures below 20-30 μm in depth are difficult to obtain, and the manufacturing error is rather high, as it is inversely proportional to the depth. Indeed, the proposed method uses a confined dehydration process of a patterned gelatin substrate fabricated via replica molding onto a micromilled poly(methyl methacrylate) substrate to produce a gelatin master with demonstrated final micrometric features down to 3 μm for the channel depth and, in specific configurations, down to 5 μm for the channel width. Finally, we demonstrated the ability to flux liquids in miniaturized microfluidic devices and fabricated and tested-as an example-micrometric microstructures arrays connected via microchannels for biological assays.