A cell delivery and pre-positioning system utilizing microfluidic devices for dual-beam optical trap-and-stretch

This study reports a new microfluidic chip capable of delivering and pre-positioning cells in a pre-defined 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. (C) 2008 Elsevier B.V. All rights reserved.