Cell sorting in micromachined silicon structures

Cell sorting has become increasingly important in basic research and medical diagnostics. We have demonstrated that magnetic activated sorting and fluorescent activated sorting can also be envisaged in microfluidic silicon structures. In these structures we take advantage of the laminar flow in microstructures. Paramagnetic particles sheeted by two buffer streams are separated from non-magnetic particles by deflection in a magnetic field gradient. Particles labelled with a fluorochrome are sheeted by two buffer streams, excited and detected by a photo multiplier tube. The photo multiplier tube switches a valve on one of the outlets of the sorter microstructure and selects a particle by forcing it to the collecting outlet. Sorting in these structures is now being optimised with paramagnetic and fluorescent beads, but ultimately it is our intention to sort living cells. One of the major advantages of microfluidic structures is the capability of integrating various functional modules. Simultaneously with optimising our sorter structures, we are investigating various levels of system integration that may improve the performance of the structure.