3D Printing of Inertial Microfluidic Devices

Abstract

Inertial microfluidics has been broadly investigated, resulting in the development of various applications, mainly for particle or cell separation. Lateral migrations of these particles within a microchannel strictly depend on the channel design and its cross-section. Nonetheless, the fabrication of these microchannels is a continuous challenging issue for the microfluidic community, where the most studied channel cross-sections are limited to only rectangular and more recently trapezoidal microchannels. As a result, a huge amount of potential remains intact for other geometries with cross-sections difficult to fabricate with standard microfabrication techniques. In this study, by leveraging on benefits of additive manufacturing, we have proposed a new method for the fabrication of inertial microfluidic devices. In our proposed workflow, parts are first printed via a high-resolution DLP/SLA 3D printer and then bonded to a transparent PMMA sheet using a double-coated pressure-sensitive adhesive tape. Using this method, we have fabricated and tested a plethora of existing inertial microfluidic devices, whether in a single or multiplexed manner, such as straight, spiral, serpentine, curvilinear, and contraction-expansion arrays. Our characterizations using both particles and cells revealed that the produced chips could withstand a pressure up to 150 psi with minimum interference of the tape to the total functionality of the device and viability of cells. As a showcase of the versatility of our method, we have proposed a new spiral microchannel with right-angled triangular cross-section which is technically impossible to fabricate using the standard lithography. We are of the opinion that the method proposed in this study will open the door for more complex geometries with the bespoke passive internal flow. Furthermore, the proposed fabrication workflow can be adopted at the production level, enabling large-scale manufacturing of inertial microfluidic devices.

Hybrid 3D printed-paper microfluidics

“…3D printing is a versatile fabrication technique that deposits material into three-dimensional space. This allows for the formation of microfluidic structures that are difficult to fabricate with standard photolithography such as rounded cross-section or complex curvilinear microchannels 16 , 17 and adapters to commonly used connection ports such as luer locks 18 and O-ring seals 19 . This technology has many other attractive features for microfluidics 20 – 22 , including its ability to print biocompatible plastics 20 , hydrogels, live cells 23 , metals 24 , sugars 25 , glass 26 , its simple integration with analytical chemistry modalities 27 , and its ability to iteratively update complex prototypes without the need for photomasks.…”

Microfluidic chip fabrication and performance analysis of 3D printed material for use in microfluidic nucleic acid amplification applications

“…To circumvent resin drainage issues, Büttner et al demonstrated a single layer exposure method based on DLP projection for printing complex channels with heights of 25-150 µm on polymethyl methacrylate (PMMA) or glass substrates [46]. Another recent work on manufacturability of microfluidics with DLP SLA was demonstrated by Bazaz et al [50]. The group printed open channel microfluidic parts which were then bonded on PMMA sheets with pressure sensitive tape.…”

“…However, similar approaches with sacrificial material has not been seen for the lower-cost DLP SLA. Different approaches to print enclosed microfluidics with DLP SLA [46,50,51] have produced successful results in their field of applications, however the main drawback lies on the use of adhesives sheets that introduce material inconsistency in the channels and impose multi-step processing.…”

High-Throughput Particle Concentration Using Complex Cross-Section Microchannels

“…When flowing through a straight rectangular microchannel, initially random suspensions of particles reach certain equilibrium positions. In certain Re, these equilibrium positions are parallel to each other and the adjacent walls [31,32]. Spontaneous lateral migration of particles in Poiseuille flow and finite channel Re arises from a balance between dominant lift forces (F L ), including shear-gradient-induced lift force (F S ), and wall induced lift force (F W ) which are orthogonal to the flow directions [33].…”