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Deterministic lateral displacement (DLD) is a microfluidic micro/nanopost array-based technique for size-based particle separations. A key challenge in scaling DLD for handling smaller particles is that creating such “nanoDLD” arrays can be cost-intensive with substantial technical hurdles. To circumvent such issues, here we explore a new “hexagonally arranged triangles (HAT)” DLD geometry that is based on patterns associated with nanosphere lithography (NSL). Finite element simulations and preliminary experiments with 0.86 μm and 4.7 μm particles suggest effective separation capabilities of the HAT-DLD approach, marking an important first step toward new classes of nanoDLD arrays fabricated through bottom-up, self-assembly-based NSL.
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Toward Deterministic Lateral Displacement-Based Continuous-Flow Microfluidic Particle Reactors via Direct Laser Writing
Multi-stage fluidic reaction schemes for suspended particles (e.g., micro/nanospheres, cells, bacterial species, and extracellular vesicles) underly a diversity of chemical and biological applications. Conventional methods for executing such protocols can be exceedingly time, labor, and/or cost intensive. Microfluidic strategies can address these drawbacks; however, such technologies typically rely on clean room-based microfabrication that suffer from similar deficits for manufacturing the chips. To simultaneously overcome these challenges, here we explore the use of the submicron-scale additive manufacturing approach, “Two-Photon Direct Laser Writing (DLW)”, as a means for fabricating micro-fluidic “Deterministic Lateral Displacement (DLD)” arrays capable of passively guiding suspended particles across discrete, adjacent flow streams—the fundamental capability of continuous-flow multi-stage particle microreactors. Experimental results from microfluidic experimentation with 5 μm-in-diameter fluorescent particles revealed effective particle transport across flow streams, with 87.5% of fluorescent peaks detected in the designated, opposing outlet following the DLD array. These results suggest utility of the presented approach for micro- and nanoparticle-based microfluidic reactors targeting wide-ranging chemical and biological applications.
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- Award ID(s):
- 1761395
- PAR ID:
- 10376837
- Date Published:
- Journal Name:
- Proceedings of the 20th Solid-State Sensors, Actuators and Microsystems Workshop (Hilton Head Workshop 2022)
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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null (Ed.)Additive manufacturing (or "three-dimensional (3D) printing") technologies offer unique means to expand the architectural versatility with which microfluidic systems can be designed and constructed. In particular, "direct laser writing (DLW)" supports submicron-scale 3D printing via two-photon (or multi-photon) polymerization; however, such high resolutions are poorly suited for fabricating the macro-to-micro interfaces (i.e., fluidic access ports) critical to microfluidic applications. To bypass this issue, here we present a novel strategy for using DLW to 3D print architecturally complex microfluidic structures directly onto-and notably, fully integrated with-macroscale fused silica tubes. Fabrication and experimental results for this "ex situ DLW (esDLW)" approach revealed effective structure-to-tube sealing, with fluidic integrity maintained during fluid transport from macroscale tubing, into and through demonstrative 3D printed microfluidic structures, and then out of designed outlets. These results suggest that the presented DLW-based printing approach for externally coupling microfluidic structures to macroscale fluidic systems holds promise for emerging applications spanning chemical, biomedical, and soft robotics fields.more » « less
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Abstract Microfluidic devices manufactured from soft polymeric materials have emerged as a paradigm for cheap, disposable and easy-to-prototype fluidic platforms for integrating chemical and biological assays and analyses. The interplay between the flow forces and the inherently compliant conduits of such microfluidic devices requires careful consideration. While mechanical compliance was initially a side-effect of the manufacturing process and materials used, compliance has now become a paradigm, enabling new approaches to microrheological measurements, new modalities of micromixing, and improved sieving of micro- and nano-particles, to name a few applications. This topical review provides an introduction to the physics of these systems. Specifically, the goal of this review is to summarize the recent progress towards a mechanistic understanding of the interaction between non-Newtonian (complex) fluid flows and their deformable confining boundaries. In this context, key experimental results and relevant applications are also explored, hand-in-hand with the fundamental principles for their physics-based modeling. The key topics covered include shear-dependent viscosity of non-Newtonian fluids, hydrodynamic pressure gradients during flow, the elastic response (deformation and bulging) of soft conduits due to flow within, the effect of cross-sectional conduit geometry on the resulting fluid–structure interaction, and key dimensionless groups describing the coupled physics. Open problems and future directions in this nascent field of soft hydraulics, at the intersection of non-Newtonian fluid mechanics, soft matter physics, and microfluidics, are noted.more » « less
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