3D printing: an emerging tool for novel microfluidics and lab‐on‐a‐chip applications

many fields such as medicine, chemistry, and biotechnologies (Barry and Ivanov 2004; Beebe et al. 2002; Dittrich and Manz 2006; Hong and Quake 2003; Stone et al. 2004; Thorsen et al. 2002; Wang et al. 2009; Weibel and Whitesides 2006; Whitesides 2006; Xu 2014; Guo et al. 2015). Fluid flow at the characteristic dimensions of microfluidic devices (MFDs) exhibits unique behavior not otherwise replicable at macroscopic scales (Karniadakis et al. 2006; Squires and Quake 2005; Hashmi et al. 2012). Currently, most microfluidic fabrication techniques are largely constrained by the complexity of real 3D structures, and limit researchers’ ability to produce complex 3D flow paths with nonstandard cross sections and of differing sizes and directions. Fortunately, the rapidly advancing 3D printing technology, also known as additive manufacturing (AM) technology, has brought us a possible route to overcome this problem. In this technology, the structure of interest is sliced into numerous 2D cross sections, and hence, the production becomes a straightforward layer-bylayer fabrication process. Such a direct approach for microfabrication is rapidly becoming established as an attractive field of interest to microfluidic engineers. The intent of this article is to introduce the state-of-the-art 3D printing technologies and its applications in fabricating microfluidics for novel experiments. We will focus on emerging applications in the past 2 years and provide our perspectives on possible future directions.