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Simultaneous optical manipulation of multiple particles inside microfluidic channels using one rectangular-shaped VCSEL

Optical trapping for isolation and sorting of cells and particles inside microfluidic channels is an efficient non-destructive manipulation technique in the field of biophotonics. In recent years, vertical-cavity surface-emitting lasers (VCSELs) have been proven to be excellent light sources for particle manipulation inside microfluidic channels. The small dimension and low power consumption of these devices enable direct integration with the channels. With such integration, however, the simultaneous manipulation or trapping of multiple particles require the usage of densely packed VCSEL arrays with very small device pitch, which makes the fabrication process more expensive and more complicated. We present an innovative technique for simultaneous optical multi-particle manipulation using one rectangular-shaped top-emitting AlGaAsGaAs VCSEL resonator having an active aperture area of around 100 × 14 μm2. The VCSEL emission wavelength is about 850 nm, which is suitable for usage in biophotonics, as biological materials present very little absorption in the near-infrared spectral range. Furthermore, this oblong VCSEL can potentially be integrated with polydimethylsiloxane (PDMS) microfluidic channels to form miniaturized optofluidic chips for ultra-compact particle handling and manipulation. We show efficient single as well as multiple polystyrene particle trapping and sorting inside PDMS microfluidic channels.