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Research Topics

  • Electroporation
  • Inertial Focusing
  • Cell Purification
  • and more...

Vortex Assisted Electroporation

Sequential multimolecular delivery via gentle vortex-assisted electroporation.
Illustration by Marc Lim .
[Exogeneous Molecular Delivery on Purified Target Cells] There is an increasing demand for techniques allowing intracellular delivery of exogenous substances with minimal toxicity for the purposes of cellular reprogramming studies, development of multigenic disorder therapies, as well as production of industrial and pharmaceutical compounds. The vortex-assisted electroporator uniquely provides the ability to sequentially deliver multiple molecules with different electroporation conditions into identical cell populations by trapping cells in microfluidic vortices as exogenous substances are serially flown over them. The developed electroporation system has practical potential as a versatile tool for cellular reprogramming studies, drug delivery applications, and studies optimizing complex molecular delivery processes. [Read more Single-chamber, JOVE , Drug cocktail analyses & Symmetric Array Electrodes ]

Precise Particle Manipulation

Massively parallel inertial focusing for imaging flow cytometry.
Illustration by Marc Lim .
[Sheathless Flow Cytometry] Flow cytometry is the gold standard in cell analysis and is regularly used for blood analysis (i.e., complete blood counts).  Flow cytometry, however, lacks sufficient throughput to analyze rare cells in blood or other dilute solutions in a reasonable time period because it is an inherently serial process.  We exploited inertial effects for label- and sheath-free parallel flow cytometry with extreme throughput (1 million cells/s) for rapid and accurate differentiation of cells. As no additional external forces are required to create ordered streams of cells, this approach has the potential for future applications in cost-effective hematology or rare cell analysis platforms with extreme throughput capabilities when integrated with suitable large field-of view imaging or interrogation methods. [Read more]


Orientation of inertially focused nonspherical disks and cylinders.
Particles were fabricated by BiNEL.
[Inertial Focusing of Nonspherical Particles] Despite rapid advancements in the field of molecular biology, fast and information-rich identification and quantification of minute analytes remains challenging for various applications. Increase in demand for such techniques has lead to development of innovative multiplexed particle-based biochemical assays. To meet the requirement for clinical applications, a method of particle manipulation in a high-throughput manner without sheath-flow or active guiding is needed. We have found that inertial effects can be utilized to focus nonspherical microparticles at uniform lateral and vertical locations. [Read more]


Cellular Biophysical Property Measurement

Mechanical properties of flowing particles can be reflected in lateral dynamic equilibrium positions, Xeq.
a/W: particle diameter to channel width ratio, λ: viscosity ratio between continuous and disperse phases
In addition to nonlinearity associated with the inertia of the fluid, nonlinear lateral migration can occur when the particle itself is deformable.  Lateral migration of deformable particles was found to result from a nonlinearity caused by matching of velocities and stresses at the particle/droplet interface. That is, the magnitude of lateral drift velocity and lift force is closely related to the deformed shape of the object.
Lateral dynamic equilibrium positions vary depending on cellular biophysical properties.
The fact that deformable particles experience an additional lift force suggests the possibility of high throughput deformability-induced particle classification and separation. Deformation-induced lift forces will act in superposition with inertial lift forces to create modified lateral equilibrium positions that are dependent on particle deformability.
[Phenotype Dependent Inertial Focusing] Single-cell deformability has recently been recognized as a unique label-free biomarker for cell phenotype and lineage determinations. As the flowing particles with different mechanial properties experience different magnitude of lift forces, the lateral equilibrium position can then be used as the measure of particle deformability when the particle size is taken into account. [Read more]

Label-free Target Cell Purification

[Target Cell Selection based on Cellular Biophysical Properties] The ability to detect and isolate rare target cells from heterogeneous samples is in high demand in cell biology research, immunology, tissue engineering and medicine.  Techniques allowing label-free cell enrichment or detection are especially important to reduce the complexity and costs towards clinical applications. In inertial microfluidics, cells with varying biophysical properties (e.g., size and deformability), can be differentially focused at distinct locations corresponding to their properties. Thus, the differences in lateral equilibrium position among cell types can be utilized for biophysical property based target cell enrichments by directing entrained target cells to separate designated outlets or by isolating target cells in geometric compartments. [Read more DACS & CCTV]
Massive CCTV
Deformability Activated Cell Sorting (DACS)
Article & Movies
Selective cell trapping using microscale vortex
Article & Movies
We are currently seeking more applications to explore. Please contact Professor Hur for collaboration.

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