Micropump actuated by droplets

Abstract

The invention relates to a micropump for which the pressure force is not limited by the electrowetting saturation angle, while being simple to manufacture. According to the invention, the microchannel ( 10 ) comprises an inlet orifice ( 11 ) and has a hydrophilic wall ( 12 ) extending from said inlet orifice ( 11 ). Displacement means are provided to displace a droplet ( 51 ) of liquid (L 1 ) by electrowetting on a hydrophobic surface ( 22 ) until said droplet ( 51 ) is brought into contact with said hydrophilic wall ( 12 ), such that said droplet ( 51 ) enters into said microchannel ( 10 ) through said inlet orifice ( 11 ) by wetting, causing displacement of said fluid (F 1 ).

1 . Micropump to displace a fluid (F 1 ) in a microchannel ( 10 ), said micropump being characterised in that:
 the microchannel ( 10 ) comprises an inlet orifice ( 11 ) and has a hydrophilic wall ( 12 ) extending from said inlet orifice ( 11 ),   and in that it comprises   means ( 51 ) for displacement of droplets of liquid (L 1 ) by electrowetting on a hydrophobic surface ( 22 ) until said droplet ( 51 ) is brought into contact with said hydrophilic wall ( 12 ), such that said droplet ( 51 ) enters into said microchannel ( 10 ) through said inlet orifice ( 11 ) by wetting, causing displacement of said fluid (F 1 ).   
   
   
       2 . Micropump according to  claim 1 , characterised in that the contact angle between said droplet ( 51 ) and said hydrophilic wall ( 12 ) is significantly less than the contact angle formed by electrowetting on said hydrophobic surface ( 22 ). 
   
   
       3 . Micropump according to  claim 1 , characterised in that said displacement means comprise at least one displacement electrode ( 31 ) and a counter-electrode electrically in contact with the droplet ( 51 ), and a voltage generator to apply a potential difference between one or several displacement electrodes ( 31 ) and said counter-electrode. 
   
   
       4 . Micropump according to  claim 3 , characterised in that said displacement means comprise a displacement electrode ( 31 ) arranged such that a liquid droplet ( 51 ) covering it is in contact with said hydrophilic wall ( 12 ) through said inlet orifice ( 11 ). 
   
   
       5 . Micropump according to  claim 1 , characterised in that said hydrophilic wall ( 12 ) has a nanotextured or microtextured surface. 
   
   
       6 . Micropump according to  claim 1 , characterised in that said hydrophilic wall ( 12 ) is made of a hydrophilic material or comprises a layer of a hydrophilic material. 
   
   
       7 . Micropump according to  claim 1 , characterised in that said hydrophilic wall ( 12 ) extends over the entire length of the microchannel ( 10 ). 
   
   
       8 . Micropump according to  claim 1 , characterised in that the microchannel ( 10 ) comprises a connection portion ( 17 ) defining an upstream portion ( 13 ) and a downstream portion ( 16 ), the cross-section of said connection portion ( 17 ) being significantly greater than the cross-section of the downstream portion ( 13 ). 
   
   
       9 . Micropump according to  claim 8 , characterised in that the size of the connection portion ( 17 ) is between 5 and 50 times the size of the upstream portion ( 13 ). 
   
   
       10 . Micropump according to  claim 8 , characterised in that a second fluid (F 2 ) is located downstream from the first fluid (F 1 ) so as to form an interface (I 2 ) with the first fluid, located in said connection portion ( 17 ). 
   
   
       11 . Micropump according to  claim 8 , characterised in that the upstream portion ( 13 ) comprises a first upstream portion ( 14 ) extending from the inlet orifice ( 11 ) and a plurality of second elementary upstream portions ( 15 ′) arranged in parallel, each communicating with said first upstream portion ( 14 ). 
   
   
       12 . Micropump according to  claim 11 , characterised in that each second elementary upstream portion ( 15 ′) communicates with said connection portion ( 17 ). 
   
   
       13 . Micropump according to  claim 12 , characterised in that each second elementary upstream portion ( 15 ′) is at least partially filled with said fluid (F 1 ). 
   
   
       14 . Micropump according to  claim 1 , characterised in that it also comprises means of forming said droplet ( 51 ) on said hydrophobic surface ( 22 ), by electrowetting. 
   
   
       15 . Micropump according to  claim 14 , characterised in that said displacement means comprising at least one displacement electrode ( 31 ), the droplet formation means comprise a plurality of droplet formation electrodes ( 42 ), one of which is adjacent to a displacement electrode ( 31 ). 
   
   
       16 . Micropump according to  claim 14 , characterised in that a second hydrophobic surface ( 26 ) is arranged facing the first hydrophobic surface ( 22 ) so as to form a closed or confined device for said droplet ( 51 ).