A Microfluidic-based Hydrodynamic Trap for Single Particles

The overall goal of this method is to confine and manipulate single micro and nanoscale particles using laminar flow in a microfluidic device. The hydrodynamic trap consists of a microfluidic device with a cross slot channel geometry, which gives rise to a stagnation point flow at the microchannel junction. An on-chip valve located in one of the outlet channels is used to actively control fluid flow and trap particles.

Particles are confined at a user-defined set point by active control of the stagnation point position. A feedback controller is used to track particle position and to regulate the on-chip valve to maintain particle position at the set point. Using the hydrodynamic trap, single particles are trapped in, dilute or concentrated particle solutions and may be imaged using fluorescence or brightfield microscopy.