High-Resolution 3D Printing Fabrication of a Microfluidic Platform for Blood Plasma Separation

Abstract

Additive manufacturing technology is an emerging method for rapid prototyping, which enables the creation of complex geometries by one-step fabrication processes through a layer-by-layer approach. The simplified fabrication achieved with this methodology opens the way towards a more efficient industrial production, with applications in a great number of fields such as biomedical devices. In biomedicine, blood is the gold-standard biofluid for clinical analysis. However, blood cells generate analytical interferences in many test procedures; hence, it is important to separate plasma from blood cells before analytical testing of blood samples. In this research, a custom-made resin formulation combined with a high-resolution 3D printing methodology were used to achieve a methodology for the fast prototype optimization of an operative plasma separation modular device. Through an iterative process, 17 different prototypes were designed and fabricated with printing times ranging from 5 to 12 min. The final device was evaluated through colorimetric analysis, validating this fabrication approach for the qualitative assessment of plasma separation from whole blood. The 3D printing method used here demonstrates the great contribution that this microfluidic technology will bring to the plasma separation biomedical devices market.

Keywords: 3D printing; fabrication; high resolution; plasma separation; stereolithography; whole blood.

Figure 1

Workflow of the iterative fabrication process and the application of the fabricated microfluidic devices for plasma separation. The first step was the design of the devices through CAD software. Then, these models were 3D printed using a high-resolution, custom-made 3D printer with custom-made resins. This allowed fast fabrication times, thus the CAD designs could be easily modified based on the fabrication-and-fail optimization method, which allowed the development of an iterative fabrication process until obtaining an optimum device.

Figure 2

3D-printed devices (resin A) and the CAD design of the lateral view of the channels. Device 3 (A) consisted of round-like chambers and three independent channels. Devices 4 (B) and 14 (C) consisted of rectangle-like sedimentation trenches and five independent channels.

Figure 3

Optimized 3D-printed microfluidic prototype (Device 15) for plasma separation. (A) Top view image of the final device. (B) CAD design of the separated channels.

Figure 4

CAD design of Device 15 with the connecting channel between the inlet reservoir and the sedimentation trench placed 800 µm above the bottom layer of the reservoir (red), and a hydrophobic air barrier of 102 µm placed at the top of the sedimentation trench (blue) to enhance separation of plasma from whole blood.

Figure 5

Workflow for plasma separation, showing a schematic diagram (side view) and top-view photos of the 3D-printed Device 15 during each step of the process. (A) First, 12 µL of whole human blood was loaded in the input reservoir and let stand for 8 min. (B) Then, negative pressure (yellow arrow) was applied at a constant flow of 1 µL min⁻¹ and the sample entered the sedimentation trench. (C) Blood cells sedimented to the bottom whereas plasma was separated due to its lower density. (D) Finally, the plasma was collected from the outlet to be further analyzed.

Figure 6

Qualitative assessment of the separated plasma through image analysis. (A) Black and white (B&W) analysis of whole blood (dark gray) and the separated plasma (light gray), where 0 = black and 255 = white (n = 3). Images at 20× magnification of a whole blood (B) and a separated plasma (C) sample drop on a slide.