Bubble-based micropump

Abstract

A micro-pump for pumping either electrically conductive or non-conductive liquids through channels of the micro-pump and/or micro-devices. A conductive or non-conductive liquid, depending on the specific application of the present invention, is disposed within a liquid chamber and/or channel of the micro-pump. An energy source is then applied to the micro-pump of the present invention in order to form one or more vapor bubbles within the channel. Thereafter the vapor bubble(s) is collapsed, and the process of forming and collapsing the vapor bubble may thereafter be repeated. By the formation and collapsing cycle of the vapor bubble, a pumping action of the liquid is effectuated thereby transporting the liquid within the micro-pump of the present invention and/or micro-devices.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is as follows:  
     
         1 . A micro-pump for pumping a liquid, comprising: 
 a channel having a first end and a second end, the channel having a cross section;    a first outer chamber in fluid communication with the first end of the channel, the first outer chamber having a cross section larger than the cross section of the channel; and    a heating unit disposed proximate to the channel for forming vapor bubbles in the channel, the heating unit providing an asymmetry for a pumping action of the liquid.    
     
     
         2 . The micro-pump of    claim 1   , further comprising: 
 a second outer chamber in fluid communication with the second end of the channel, the second outer chamber having a cross section larger than the cross section of the channel.    
     
     
         3 . T he micro-pump of    claim 2   , wherein the cross section of the channel and the first and second outer chambers are one of circular, oval, triangular and square.  
     
     
         4 . The micro-pump of    claim 2   , wherein a ratio of the cross sections of the first and second outer chamber to the channel is 5 to 1 or more.  
     
     
         5 . The micro-pump of    claim 2   , wherein the heating unit is two or more heaters disposed along a length of the channel.  
     
     
         6 . The micro-pump of    claim 5   , wherein the two or more heaters is three heaters.  
     
     
         7 . The micro-pump of    claim 5   , wherein the two or more heaters are embedded along one of a base, sides and a top of the channel.  
     
     
         8 . The micro-pump of    claim 5   , wherein the two or more heaters provide localized heating in successive order along the channel in order to form in successive order a plurality of vapor bubbles in the channel in either a first direction or a second opposite direction.  
     
     
         9 . The micro-pump of    claim 2   , wherein the channel and the first and second outer chamber are made of one of a conductive and a non-conductive material.  
     
     
         10 . The micro-pump of    claim 2   , wherein the first and second channels are in an in-line flow path with the channel.  
     
     
         11 . The micro-pump of    claim 1   , wherein the heating unit is placed at a distance approximately in the range of 20%-40% of the channel length from the first outer channel.  
     
     
         12 . The micro-pump of    claim 1   , wherein: 
 the heating unit is a first heater and a second heater,    the first heater is energized to form vapor bubbles in the channel to provide a pumping action of the liquid in a first direction, and    the second heater is energized to form vapor bubbles in the channel to provide a pumping action of the liquid in a second direction opposite the first direction in the channel.    
     
     
         13 . A micro-pump for pumping liquid, comprising: 
 a center channel having a cross section and opposing first and second ends;    an opposing first chamber being disposed at the first opposing end of the center channel, the opposing first channel having a cross section larger than the cross section of the center channel;    an opposing second chamber being disposed at the second opposing end of the center channel, the opposing second chamber having a cross section larger than the cross section of the center channel; and    at least two heaters disposed along a length of the center channel in order to provide a bi-directional pumping action in which a flow direction of the liquid is dependent on which of the at least two heaters are energized.    
     
     
         14 . The micro-pump of    claim 13   , wherein the first and second opposing chambers are one of non-conductive and electrically conductive material.  
     
     
         15 . The micro-pump of    claim 13   , wherein the cross section of the center channel and the cross sections of the first and second opposing chambers are one of circular, oval, triangular and square.  
     
     
         16 . The micro-pump of    claim 13   , wherein a ratio of the cross section of the first and second opposing chambers to the center channel is 5 to 1 or more.  
     
     
         17 . The micro-pump of    claim 13   , wherein the at least two heaters are three heaters.  
     
     
         18 . The micro-pump of    claim 17   , wherein the three heaters are embedded along one of a base, sides and top of the center channel.  
     
     
         19 . The micro-pump of    claim 13   , wherein the at least two heaters provide localized heating in successive order along the center channel in order to form in successive order a plurality of vapor bubbles in the channel.  
     
     
         20 . The micro-pump of    claim 13   , wherein the first and second opposing chambers are in an in-line flow path with the center channel.  
     
     
         21 . A method of pumping a liquid in a micro-pump, the micro-pump including a center channel for transporting the liquid therein, the method comprising the steps of: 
 providing localized heat to the liquid;    forming a vapor bubble from the liquid at a location of the localized heat; and    collapsing the vapor bubble,    wherein providing localized heat is provided by two or more heaters along the center channel in order to push the liquid in the center channel between two opposing chambers each having a cross section larger than a cross section of the center channel.    
     
     
         22 . The method of    claim 21   , wherein during bubble formation the liquid is passed in a direction to either of the opposing in-line chambers.  
     
     
         23 . The method of    claim 22   , wherein each of the at two or more heaters are briefly powered in succession such that vapor bubbles form at each of the at two or more heaters and a timing of the heating of each of the two or more heaters is such that when a vapor bubble is beginning to collapse, a new vapor bubble grows at a next of the each of the two or more heaters.