Pulsed laser activated cell sorter (PLACS) for high-throughput fluorescent mammalian cell sorting

Abstract

We present a Pulsed Laser Activated Cell Sorter (PLACS) realized by exciting laser induced cavitation bubbles in a PDMS microfluidic channel to create high speed liquid jets to deflect detected fluorescent samples for high speed sorting.Pulse laser triggered cavitation bubbles can expand in few microseconds and provide a pressure higher than tens of MPa for fluid perturbation near the focused spot. This ultrafast switching mechanism has a complete on-off cycle less than 20 μsec. Two approaches have been utilized to achieve 3D sample focusing in PLACS. One is relying on multilayer PDMS channels to provide 3D hydrodynamic sheath flows. It offers accurate timing control of fast (2 m sec -1 ) passing particles so that synchronization with laser bubble excitation is possible, an critically important factor for high purity and high throughput sorting. PLACS with 3D hydrodynamic focusing is capable of sorting at 11,000 cells/sec with >95% purity, and 45,000 cells/sec with 45% purity using a single channel in a single step. We have also demonstrated 3D focusing using inertial flows in PLACS. This sheathless focusing approach requires 10 times lower initial cell concentration than that in sheath-based focusing and avoids severe sample dilution from high volume sheath flows. Inertia PLACS is capable of sorting at 10,000 particles sec -1 with >90% sort purity.

On the application of hydrodynamic cavitation on a chip in cellular injury and drug delivery

“…2,3 Hence, cavitation bubbles have been heavily utilized during the last decade for cell lysis, permeabilization, sorting, imaging, and lithotripsy. [4][5][6][7][8][9] A growing number of studies have revealed that cavitation bubbles could generate pores on the cell membrane. For instance, Li et al 10 employed a single cavitation bubble generated by a pulsed laser beam before developing jet flow focused on a single trapped cell in suspension, and the microfluidic system allowed the generation of a single cavitation bubble and a single trapped cell in more controllable poration.…”