Parallel transport of biological cells using individually addressable VCSEL arrays as optical tweezers

We have demonstrated the use of vertical cavity surface emitting lasers (VCSELs) for optical trapping and active manipulation of live biological cells and microspheres. We have experimentally verified that the Laguerre–Gaussian laser mode output from the VCSEL functions just as well as the traditional Gaussian fundamental laser mode for optically trapping biological cells and may be preferable since the highest intensity of the Laguerre–Gaussian mode is located at the outer ring of the optical aperture, which allows for stronger optical confinement to be obtained for a lower total power. Another advantage that VCSELs have over conventional gas and diode lasers is their ability to be manufactured in an array form. Using a 2×2 array of VCSELs, the simultaneous and independent transport of four human red blood cells is demonstrated indicating that much larger two-dimensional VCSEL arrays can be used as individually addressable optical tweezers in biological chips and systems. This parallel transport capability will have a significant impact in currently developing biochip array and assay technologies through the facilitation of the selection, relocation, and precision placement of cells.