Three-dimensional printed microfluidic modules for design changeable coaxial microfluidic devices

Coaxial microfluidic devices have been widely used for the preparation of monodisperse droplets and multilayered hydrogel fibers. However, in the formation of the coaxial microfluidic devices, as the configurations of the coaxial channels become larger and more complicated, the production time is prolonged, the yield is reduced, and there are difficulties associated with rinsing the channels. In this paper, we propose three-dimensional (3D) printed microfluidic modules as connectable platforms for the preparation of coaxial microfluidic devices. Since the microfluidic modules have simple channel configurations, we can easily fabricate them with a 3D printer and rinse their channels after use. The combination of the microfluidic modules allows the formation of various types of coaxial microfluidic devices, such as axisymmetric flow-focusing devices and co-flow devices with specified dimensions for their channels. Therefore, devices comprising these microfluidic modules have succeeded in production of monodisperse droplets and hydrogel fibers with various dimensions and different numbers of layers. Furthermore, as a demonstration of biofabrication applications, we show that the device comprising the microfluidic modules enables us to fabricate a multi-layered cell-laden fiber by gelation of cell-laden collagen solutions in a multi-layered laminar flow state. We believe that the microfluidic modules will be useful for preparing coaxial microfluidic devices for various applications in analytical chemistry, biology, and tissue engineering.