Continuous sorting of heterogeneous-sized embryoid bodies

Mechanical and Aerospace Engineering Department, University of California, Los Angeles, CA, USA.
Lab on a Chip (Impact Factor: 6.12). 04/2010; 10(13):1678-82. DOI: 10.1039/c000163e
Source: PubMed


This paper presents a microfluidic device for sorting embryoid bodies (EBs) with large dynamic size ranges up to 300 microm. The proposed separation scheme utilizes appropriately spaced pillars within a microchannel to alter the fluid flow pathway, thus allowing particles of defined sizes to be diverted towards specific flow paths. We test the device functionality by separating polystyrene beads 90, 175 and 275 microm in diameter, demonstrating separation efficiencies approaching 100%. We then demonstrate for the first time on-chip separation of mouse EBs, which were separated into three size groups. The ability to extract specific size ranges of EBs will greatly facilitate their subsequent differentiation studies.

Full-text preview

Available from:
  • [Show abstract] [Hide abstract]
    ABSTRACT: A microfluidic device is presented for the serial formation, storage and retrieval of water microdroplets in oil. The principle of operation is similar to that of an electronic shift register. Droplets, considered as units of information, can be arrayed and serially shifted within the device, allowing the controllable positioning of the emulsions and the creation of interfaces between drops. Using this passive system, by exploiting the balance between hydrodynamic pressure and surface tension across a drop due to the device design, droplet networks can be readily arrayed in a series of elements and cascaded within the microchannels in an automatable and high throughput fashion. The results showed the suitability of the system to be used for the formation of artificial lipid bilayers and for the study of biological dynamic processes based on the diffusion of molecules through interfaces.
    No preview · Article · Nov 2010 · Lab on a Chip
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents novel methods for precisely controlling water droplets by use of a microfluidic bifurcation channel with outlet restrictions, based on droplet bistability which utilizes the Laplace pressure due to interfacial tension arising when a droplet encounters a narrow restriction. We implement droplet bistable geometry, which has two symmetric branches and restrictions, to operate as capillary valves, so that a droplet can be trapped in front of a restriction and released through it when the next droplet arrives at the other restriction. It is observed that this trap-and-release occurs repeatedly and regularly by the succeeding droplets. It is also found that there is a critical flow rate to achieve droplet bistability which occurs only when the apparent Laplace pressure surpasses the pressure drop across the droplet. By adopting a simplified hydrodynamic resistance model, droplet bistable mechanism is clearly explained. Droplet bistability enables simple and precise control of droplets at a bifurcation channel. Thus, by an appropriate channel design to induce droplet bistability, precise control of droplet traffic is achieved at a bifurcation channel connected with a single inlet channel and two outlet channels. In particular, we are able to distribute droplets at a junction in a manner of perfect alternation between the two outlet channels. Bistable components can be used as an elaborately embedded droplet traffic signal for red light (trap) and green light (release) in complex microfluidic devices, where droplets provide both the chemical or biological materials and the processing signal.
    No preview · Conference Paper · Jan 2011
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cell separation based on microfluidic affinity chromatography is a widely used methodology in cell analysis research when rapid separations with high purity are needed. Several successful examples have been reported with high separation efficiency and purity; however, cell capture at the inlet area and inlet design have not been extensively described or studied. The most common inlets-used to connect the microfluidic chip to pumps, tubing, etc.-are vertical (top-loading) inlets and parallel (in-line) inlets. In this work, we investigated the cell capture behavior near the affinity chip inlet area and compared the different performances of vertical inlet devices and parallel inlet devices. Vertical inlet devices showed significant cell capture capability near the inlet area, which led to the formation of cell blockages as the separation progressed. Cell density near the inlet area was much higher than that in the remaining channel, whereas for parallel inlet chips cell density at the inlet area was similar to that in the rest of the channel. In this paper, we discuss the effects of inlet type on chip fabrication, nonspecific binding, cell capture efficiency, and separation purity. We also discuss the possibility of using vertical inlets in negative-selection separations. Our findings show that inlet design is critical and must be considered when fabricating cell affinity microfluidic devices.
    Full-text · Article · Feb 2011 · Analytical Chemistry
Show more