Method and device for monitoring and controlling fluid locomotion

Abstract

A device for monitoring dripping of a fluid from a fluid channel, the device comprises a capacitor, being formed on or integrated with the fluid channel, and electrical contacts, connecting the capacitor to a capacitance measuring device, the capacitor is designed and constructed so that a change in a capacitance thereof represents a formation of a drop near an edge of the fluid channel.

1 .- 151 . (canceled) 
   
   
       152 . A device for monitoring dripping of a fluid from a fluid channel, the device comprising a capacitor, being formed on or integrated with the fluid channel, and electrical contacts, connecting said capacitor to a capacitance measuring device, said capacitor is designed and constructed so that a change in a capacitance thereof represents a formation of a drop near an edge of the fluid channel. 
   
   
       153 . The device of  claim 152 , wherein the fluid channel is a capillary. 
   
   
       154 . The device of  claim 153 , wherein said capacitor comprises two conductive plates engaging opposite faces of said capillary. 
   
   
       155 . The device of  claim 152 , wherein the fluid channel is an HPLC column. 
   
   
       156 . The device of  claim 155 , wherein said capacitor comprises two conductive plates engaging opposite faces of said HPLC column. 
   
   
       157 . The device of  claim 155 , further comprising said capacitance measuring device and electronic circuitry, communicating with said capacitance measuring device and operable to signal an automatic system to selectively collect drops. 
   
   
       158 . The device of  claim 152 , wherein the fluid channel is a microchannel of a microfluidic device. 
   
   
       159 . The device of  claim 158 , wherein said capacitor comprises two conductive plates engaging opposite walls of said microchannel. 
   
   
       160 . The device of  claim 158 , wherein said microfluidic device is selected from the group consisting of a drop ejector, a droplet microswitch an extracellular electrode and a multi electrode array. 
   
   
       161 . The device of  claim 160 , wherein said drop ejector is selected from the group consisting of an inkjet printing head and a device for preparing a microarray. 
   
   
       162 . The device of  claim 152 , wherein the fluid channel is a micropipette. 
   
   
       163 . The device of  claim 152 , wherein a size of said capacitor is in a nanometer scale. 
   
   
       164 . The device of  claim 152 , wherein a size of said capacitor is in a millimeter scale. 
   
   
       165 . The device of  claim 152 , wherein a size of said capacitor is in a centimeter scale. 
   
   
       166 . The device of  claim 152 , wherein said capacitance measuring device is configured and designed to allow measuring of capacitance at a resolution of less than about 10% of a total capacitance of said capacitor. 
   
   
       167 . The device of  claim 152 , being incorporated in an automatic positioning system. 
   
   
       168 . A method of manufacturing a device for monitoring dripping of a fluid, the method comprising:
 (a) positioning a capacitor on a fluid channel in a manner that a change in a capacitance of said capacitor represents a formation of a drop near an edge of said fluid channel; and   (b) connecting said capacitor to a capacitance measuring device using electrical contacts.   
   
   
       169 . The method of  claim 168 , wherein the fluid channel is a capillary. 
   
   
       170 . The method of  claim 169 , wherein said step of positioning said capacitor comprises:
 (i) providing a pullable tube having a profile;   (ii) pulling said tube at a controlled rate so as to provide a capillary having a predetermined profile; and   (iii) applying two conductive plates on opposite faces of said capillary.   
   
   
       171 . The method of  claim 168 , wherein the fluid channel is an HPLC column. 
   
   
       172 . The method of  claim 171 , wherein said step of positioning said capacitor comprises:
 (i) providing a capillary;   (ii) applying two conductive plates on opposite faces of said capillary; and   (iii) filling said capillary with an HPLC stationary phase.   
   
   
       173 . The method of  claim 168 , wherein the fluid channel is a microchannel of a microfluidic device. 
   
   
       174 . The method of  claim 173 , wherein said step of positioning said capacitor comprises:
 (i) etching a non conductive substrate so as to provide a microchannel having walls; and   (ii) applying two conductive plates on opposite walls of said microchannel.   
   
   
       175 . The method of  claim 174 , wherein said step of applying said two conductive plates comprises coating said opposite walls by a conductive material. 
   
   
       176 . The method of  claim 173 , wherein said microfluidic device is selected from the group consisting of a drop ejector, a droplet microswitch an extracellular electrode and a multi electrode array. 
   
   
       177 . A method of monitoring dripping of a fluid from a fluid channel, the method comprising continuously measuring capacitance changes of a capacitor being formed on or integrated with the fluid channel, and using said capacitance changes to monitor a formation of a drop near an edge of the fluid channel. 
   
   
       178 . The method of  claim 177 , wherein the fluid is selected from the group consisting of water, a body fluid, a bacterial cell suspension, a protein solution, an antibody solution, a nucleic acid solution and ink. 
   
   
       179 . A device for controlling fluid locomotion in a fluid channel, the device comprising:
 (a) a capacitor, being formed on or integrated with the fluid channel and having a variable cross-sectional area; and   (b) electrical contacts, connecting said capacitor to a voltage source;   said capacitor being operable to induce polarization on molecules of the fluid so as to generate dielectrophoretic forces thereon thereby to control fluid locomotion.   
   
   
       180 . A method of manufacturing a device for controlling fluid locomotion, the method comprising:
 (a) positioning a capacitor having a variable cross-sectional area on a fluid channel, said capacitor being operable to induce polarization on molecules of the fluid so as to generate dielectrophoretic forces thereon thereby to control fluid locomotion; and   (b) connecting said capacitor to a voltage source using electrical contacts.   
   
   
       181 . A method of controlling fluid locomotion in a fluid channel, the method comprising, using a variable cross-sectional area capacitor, being formed on or integrated with the fluid channel, for creating a non-uniform electric field capable of inducing polarization on molecules of the fluid, so as to generate dielectrophoretic forces on said molecules, thereby to control fluid locomotion.