Abstract
An apparatus and method for forming a bubble within a microchannel of a microinjector to function as a valve mechanism between the chamber and manifold, that provides for a high resistance to liquid exiting the chamber through the manifold during fluid ejection through an orifice and that also provides a low resistance to refilling of liquid into the chamber after ejection of fluid and collapse of the bubble. This effectively minimizes cross talk between adjacent chambers and increases injection frequency of the microinjector. The formation of a second bubble within the chamber coalesces with a first formed bubble between the chamber and manifold to abruptly terminate the ejection of fluid, thereby eliminating satellite droplets.