Facile fabrication of helical microfluidic channel based on rope coiling effect

A rapid and simple fabrication approach to achieve helical microfluidic channels with circular cross section using template-assisted method is proposed in this article based on rope coiling effect in the extrusion process of a desktop 3D printer. Rope coil effect is a common phenomenon in the falling process of a slender string of viscous fluid and is used to fabricate helical microstructures served as the templates in the sacrificial template-assisted method, which holds great promise to fabricate micro-channels with desired vascular architectures. The helical microstructures are fabricated with the high viscous PVA (Polyvinyl alcohol) paste extruded out of the nozzle orifice from a certain falling height. After the PDMS block embedded with PVA helical template has been fabricated, the template would then be removed by melting in hot water easily to obtain the microfluidic channels. Two major processing parameters, falling height and flow rate are studied in relation to two main geometric features of helical structures: coil diameter and wire diameter. Besides, the dimension and the shape of helical microstructures are further studied for fabrication of microfluidic channels with varying geometric parameters. The presented method facilitates the rapid and convenient construction of three-dimensional (3D) helical microfluidic channels for a wide variety of lab-on-chip applications.