Moving from millifluidic to truly microfluidic sub-100-μm cross-section 3D printed devices

Abstract

Three-dimensional (3D) printing has generated considerable excitement in recent years regarding the extensive possibilities of this enabling technology. One area in which 3D printing has potential, not only for positive impact but also for substantial improvement, is microfluidics. To date many researchers have used 3D printers to make fluidic channels directed at point-of-care or lab-on-a-chip applications. Here, we look critically at the cross-sectional sizes of these 3D printed fluidic structures, classifying them as millifluidic (larger than 1 mm), sub-millifluidic (0.5-1.0 mm), large microfluidic (100-500 μm), or truly microfluidic (smaller than 100 μm). Additionally, we provide our prognosis for making 10-100-μm cross-section microfluidic features with custom-formulated resins and stereolithographic printers. Such 3D printed microfluidic devices for bioanalysis will accelerate research through designs that can be easily created and modified, allowing improved assays to be developed.

Keywords: Bioanalytical methods; Microfluidics/microfabrication; Separations/instrumentation.

Figure 1

Example of a 3D printed device with external features laminated to form fluidic structures. (a) Image of a completed device. (b–c) Configuration of optical fibers; fiber sizes are listed. Adapted with permission from [23], arrows added for clarity.

Figure 2

Achieved internal 3D printed fluidic channel cross-sectional areas as a function of printer resolution specifications. The printer X/Y resolution is multiplied by the step size Z to give the printer X/Y–Z specification.

Figure 3

3D printed device used to study drug effects on cells. (a) Photograph of a device connected to input/output lines. (b) Schematic showing the side view of design. Reprinted with permission from [6] Copyright 2013 American Chemical Society.

Figure 4

Microfluidic pumps and valves. (a) Schematic showing valves and a displacement chamber that make a pumping unit. (b) Top view photograph of a printed pump with multiple inputs. (c) Photograph of a pump with the same orientation as the schematic. Reprinted from ref. [45].