Abstract
In this paper we demonstrate that 3D printing with a digital light processor stereolithographic (DLP-SLA) 3D printer can be used to create high density microfluidic devices with active components such as valves and pumps. Leveraging our previous work on optical formulation of inexpensive resins (RSC Adv., 2015, 5, 106621), we demonstrate valves with only 10% of the volume of our original 3D printed valves (Biomicrofluidics, 2015, 9, 016501), which were already the smallest that have been reported. Moreover, we show that incorporation of a thermal initiator in the resin formulation along with a post-print bake can dramatically improve the durability of 3D printed valves up to 1 million actuations. Using two valves and a valve-like displacement chamber (DC), we also create compact 3D printed pumps. With 5-phase actuation and a 15 ms phase interval, we obtain pump flow rates as high as 40 μL min(-1). We also characterize maximum pump back pressure (i.e., maximum pressure the pump can work against), maximum flow rate (flow rate when there is zero back pressure), and flow rate as a function of the height of the pump outlet. We further demonstrate combining 5 valves and one DC to create a 3-to-2 multiplexer with integrated pump. In addition to serial multiplexing, we also show that the device can operate as a mixer. Importantly, we illustrate the rapid fabrication and test cycles that 3D printing makes possible by implementing a new multiplexer design to improve mixing, and fabricate and test it within one day.
Highlights
MaterialsThe specific resin formulation employed for the work reported in this paper is the 0.4% Sudan I resin discussed in Ref. 8
In this paper we have demonstrated the potential of 3D printing to enable both rapid fabrication iteration and high density integration of microfluidic components
We have reported the smallest yet 3D printed valves and characterized valve performance and durability
Summary
The specific resin formulation employed for the work reported in this paper is the 0.4% Sudan I resin discussed in Ref. 8 It is prepared by mixing 0.4% (w/w) Sudan I, 1% (w/w) Irgacure 819, and 0.01% (w/w) AIBN with PEGDA, and sonicating for 30 minutes. Microfluidic devices in an individual print run are fabricated on a glass slide (25 mm x 37.5 mm x 1.2 mm) which is attached to the printer build table with double-sided tape. The first is that they avoid the need to fabricate the first device layer on the rough (anodized Al) surface of the 3D printer build table, which, especially for resins with high optical absorbance, requires a significantly longer exposure time for the first layer to attach to the build table. The second reason is that the smooth surfaces of the glass slide offer convenient optical access to observe the interior components of the microfluidic device
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