Pulsed laser triggered high speed microfluidic switch

We report a high-speed microfluidic switch capable of achieving a switching time of 10 mu s. The switching mechanism is realized by exciting dynamic vapor bubbles with focused laser pulses in a microfluidic polydimethylsiloxane (PDMS) channel. The bubble expansion deforms the elastic PDMS channel wall and squeezes the adjacent sample channel to control its fluid and particle flows as captured by the time-resolved imaging system. A switching of polystyrene microspheres in a Y-shaped channel has also been demonstrated. This ultrafast laser triggered switching mechanism has the potential to advance the sorting speed of state-of-the-art microscale fluorescence activated cell sorting devices. (C) 2008 American Institute of Physics.Physics, AppliedSCI(E)EI14ARTICLE14null9