An optofluidic device includes: a housing having an inlet port coupled to an inlet side and an outlet port coupled to an outlet side; and a microlens disposed within the housing between the inlet side and the outlet side. A fluid having a plurality of particles flows from the inlet side through the microlens to the outlet side. The optofluidic device further includes a light source configured to emit a light beam in a direction opposite flow direction of the fluid, the light beam defining an optical axis that is perpendicular to the microlens.