Direct, one-step molding of 3D-printed structures for convenient fabrication of truly 3D PDMS microfluidic chips

In this work, we developed a convenient, one-step soft-lithographic-based molding technique for molding truly 3D microfluidic channels in polydimethylsiloxane (PDMS) by overcoming two grand challenges. We optimized the post-treatment conditions for 3D-printed resin structures to facilitate the use of them as masters for PDMS replica molding. What is more important, we demonstrated a novel method for single-step molding from 3D-printed microstructures to generate truly 3D microfluidic networks easily. With this technique, we fabricated some key, functional 3D microfluidic structures and components including a basket-weaving network, a 3D chaotic advective mixer and microfluidic peristaltic valves. Furthermore, an interesting "injection-on-demand" microfluidic device was also demonstrated. Our technique offers a simple, fast route to the fabrication of 3D microfluidic chips in a short time without clean-room facilities.