Methods of penning micro-objects using positive dielectrophoresis

Abstract

Methods of selectively positioning a micro-object in a microfluidic device are described in this application. The microfluidic device can comprise an enclosure having an inlet, an outlet, and a flow region connecting the inlet and outlet, and an electrode activation substrate having a photoconductive layer. The methods of selectively positioning can comprising: projecting a first light beam on an electrode activation substrate of the microfluidic device, wherein the first position is proximal to the first micro-object, and wherein the first light beam activates a positive dielectrophoresis (DEP) force within the enclosure sufficient to capture the first micro-object; and projecting a second light beam upon a second position on the electrode activation substrate, wherein the second position is adjacent to or at least partially surrounding the first position, without overlapping the first position, the second light beam activating a positive DEP force within the enclosure sufficient to capture second micro-objects other than the first micro-object. The methods of selectively positioning can further comprise moving the first light beam towards a third position on the electrode activation substrate, wherein the DEP force activated by the first light beam is sufficient to move the first micro-object to the third position. Optionally, the methods can include moving the second light beam in relation to the first light beam to prevent micro-objects other than the first micro-object from being captured by the first light beam. Other embodiments are described.