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Publications (2)0 Total impact

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    ABSTRACT: We used one-dimensional oscillatory optical tweezers in a discrete scanning (or jumping) mode to trap and stretch individual mice erythrocytes and measured their deformation as a function of the jumping distance of the oscillatory trapping beam. In general, we observed that the length of the long axis of red blood cells (RBCs) decreased slightly at small jumping distance and then increased after the jumping distance exceeded a threshold value on the order of a few microns, which is consistent with a recent theoretical prediction. The deformability of three types of mice RBCs, namely the wide-type mice (serving as the control group), old mice, and gene knockout mice were measured and compared. Statistical analysis of their deformability reveals that the RBCs of old mice can be distinguished from those of knockout mice even though these two types of mice exhibit many similar aging-like features.
    NanoScience + Engineering; 08/2008
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    ABSTRACT: This study reports a new microfluidic chip capable of delivering and pre-positioning cells in a predefined trapping zone, and followed by manipulation of buried optical fibers for on-chip, dual-beam, optical trapping and stretching. In this microfluidic system, microchannels, micropumps, microvalves, dielectrophoretic (DEP) electrodes and active fiber manipulators were fabricated and integrated using micro-electro-mechanical-systems technology to perform several crucial functions including transportation, pre-positioning and manipulation of cells. Experimental results showed that by integrating three micropumps connected in series, the cell samples were automatically delivered into the flow focusing area and then transported to the trapping zone. A single cell can be confined by microvalves and then elevated towards the optical trapping zone by a negative-DEP force operated at a low voltage (20 Vp–p) and at a specific frequency (900 kHz). The active fiber manipulators can be used for optical trapping, manipulation, and stretching. A red blood cell was successfully trapped and stretched by a dual-beam, optical trap using the proposed microfluidic system. The developed system is promising for further applications that require trapping, manipulation and biomechanical analysis of a single cell or particle.
    Sensors and Actuators B: Chemical. 01/2008;