Sorting and lysis of single cells by BubbleJet technology

We demonstrate that chip-integrated BubbleJet technology can be used for cell sorting as well as for single-cell lysis. Vapor bubbles on the millisecond timescale are generated by titanium microheaters manufactured on transparent glass wafers. A PDMS layer is bonded on top of the glass wafer and defines microfluidic channels. Cell sorting is demonstrated with mouse fibroblasts which are hydrodynamically focused and travel at velocities of about 500 μm/s. For cell sorting the bubble generators are placed outside the microfluidic channel but are connected to it via a 20 μm nozzle. Randomly selected fibroblasts have been deflected laterally up to 60 μm from their original streamline to a collector outlet by actuation. Single-cell lysis is performed by bubble generators placed inside a flow channel directly below the cells’ path. Bubble generation pushes the cells towards the channel ceiling or the channel wall and cells are lysed due to the large shear force at an efficiency of 100%. Cycle times for sorting and lysis have experimentally been determined to be 5 ms and 20 ms, respectively.