Apparatus and method for using bubble as virtual valve in microinjector to eject fluid

An apparatus for using bubble as virtual valve in a microinjector to eject liquid, comprising:

• (a) a chamber;
• (b) a manifold in flow communication with said chamber for supplying liquid to said chamber;
• (c) an orifice in flow communication with said chamber;
• (d) means for generating a first bubble within said chamber to serve as a virtual valve when said chamber is filled with liquid, said first bubble generating means disposed proximately adjacent said orifice and external to said chamber;
• and
• (e) means for generating a second bubble subsequent to formation of the first bubble, said second bubble generating means disposed proximately adjacent said orifice and external to said chamber wherein said orifice is disposed between said first bubble generating means and said second bubble generating means, and wherein the formation of said second bubble causes fluid in said chamber to eject through said orifice.

A method for ejecting fluid from a microchannel having an orifice, comprising the steps of:

• (a) generating a first bubble proximately adjacent the orifice in a liquid-filled microchannel;
• (b) generating a second bubble proximately adjacent the orifice in said microchannel to pressurize the microchannel to eject fluid therefrom, said second bubble generating step performed after said first bubble generating step, wherein said first bubble and said second bubble each juxtapose the orifice;
• (c) enlarging said first bubble in the microchannel to serve as a virtual valve for restricting liquid flow into the microchannel;
• and
• (d) enlarging said second bubble in the microchannel, whereby said first bubble and said second bubble approach each other to abruptly terminate the ejection of liquid through the orifice.

A method for ejecting liquid from a microinjector having a chamber, a manifold for supplying liquid to the chamber and an orifice in flow communication with the chamber, comprising the steps of:

• (a) generating a first bubble proximately adjacent the orifice in the chamber when the chamber is filled with liquid, to serve as a virtual valve therein;
• (b) generating a second bubble proximately adjacent the orifice to eject liquid through the orifice, wherein said second bubble generating step is performed after said first bubble generating step;
• and
• (c) coalescing said first bubble and said second bubble to abruptly cut off the ejection of liquid through the orifice.