Leveraging the third dimension in microfluidic devices using 3D printing: no longer just scratching the surface

Abstract

3D printers utilize cutting-edge technologies to create three-dimensional objects and are attractive tools for engineering compact microfluidic platforms with complex architectures for chemical and biochemical analyses. 3D printing's popularity is associated with the freedom of creating intricate designs using inexpensive instrumentation, and these tools can produce miniaturized platforms in minutes, facilitating fabrication scaleup. This work discusses key challenges in producing three-dimensional microfluidic structures using currently available 3D printers, addressing considerations about printer capabilities and software limitations encountered in the design and processing of new architectures. This article further communicates the benefits of using three-dimensional structures, including the ability to scalably produce miniaturized analytical systems and the possibility of combining them with multiple processes, such as mixing, pumping, pre-concentration, and detection. Besides increasing analytical applicability, such three-dimensional architectures are important in the eventual design of commercial devices since they can decrease user interferences and reduce the volume of reagents or samples required, making assays more reliable and rapid. Moreover, this manuscript provides insights into research directions involving 3D-printed microfluidic devices. Finally, this work offers an outlook for future developments to provide and take advantage of 3D microfluidic functionality in 3D printing. Graphical abstract Creating three-dimensional microfluidic structures using 3D printing will enable key advances and novel applications in (bio)chemical analysis.

Keywords: 3D printing; Device interconnects; Droplet formation; Microfluidics/microfabrication; Miniaturized systems.

Fig. 1

3D printed devices containing chip-to-chip interconnections for high-density fluidic routing. a) Schematic illustration and b) photograph of the device. This system has two independent sets of flow channels (red and blue) crossing up and down the chips. One channel was filled with red food coloring, and the other with blue food coloring. Reproduced from Ref. [25] with permission from the Royal Society of Chemistry.

Fig. 2

Schematic illustration of a compact microfluidic system for nucleic acid quantification. a) Monoliths (yellow) with pump and valves. b) Device chip. c) Device chip integrated with larger interface chip. d) Upside-down close-up view of device chip fluidically and pneumatically integrated with interface chip using microgasket-based compression seals.

Fig. 3

3D printed devices containing miniaturized and integrated microfluidic channels. a) Diffusional mixing systems are created by combining two channels in a narrow junction. b) Schematic and microscope images of 3D printed devices containing a 10-stage 2-fold serial dilution component. Adapted from Noriega et al. [29], licensed under Creative Commons CC BY 4.0.

Fig. 4

3D printed microdroplet generators. a) Standard planar droplet generator design; (right) influence of resin composition on droplet formation. b) 3D annular channel-in-channel design showing stable droplet formation in a hydrophilic 3D printed polymer. Adapted from Warr et al. [19], licensed under Creative Commons CC BY 4.0.