Method for controlling the contact angle of a droplet in electrowetting and an apparatus using the droplet formed thereby

Abstract

A method for controlling the hydrophilic droplet using the electrowetting principle is disclosed. More specifically, the present invention provides a method for increasing the change of the contact angle in the interface that is formed between the hydrophilic droplet and the nonpolar fluid by adding a constant concentration of two-element electrolyte or three-element electrolyte to the hydrophilic droplet; and an apparatus for controlling the droplet having the change of the contact angle and velocity scope increased by the method.

1 . A droplet control apparatus comprising
 a first non-conductive substrate;   a first electrode arranged on an upper side of the first substrate;   a second non-conductive substrate, arranged opposite the upper side of the first substrate, for forming a predetermined space;   a second electrode arranged on the surface of the second substrate adjacently to the space and opposite to the upper side of the first substrate;   an insulating membrane positioned between the space and the first electrode or between the space and the second electrode;   a hydrophobic membrane positioned between the space and the first electrode or between the space and the second electrode;   a hydrophilic droplet located in the space and comprising two-element electrolyte or three-element electrolyte; and   a nonpolar fluid located in the space.   
     
     
         2 . The droplet control apparatus according to  claim 1 , wherein the hydrophilic droplet includes one or more materials selected from the group consisting of an ionic particle, a neutral particle, a biomaterial and a magnetic particle. 
     
     
         3 . The droplet control apparatus according to  claim 2 , wherein the biomaterial includes one or more materials selected from the group consisting of a nucleic acid, a protein, a peptide, a bacterium, a virus and a mammal cell. 
     
     
         4 . The droplet control apparatus according to  claim 1 , wherein the nonpolar fluid is oil or air. 
     
     
         5 . The droplet control apparatus according to  claim 1 , wherein the two-element electrolyte is alkali metal halide, and the three-element electrolyte is alkali metal sulfate or alkali metal nitrate. 
     
     
         6 . The droplet control apparatus according to  claim 1 , wherein the two-element electrolyte or three-element electrolyte is added in a concentration of 1 mM to 100 mM. 
     
     
         7 . The droplet control apparatus according to  claim 6 , wherein the two-element electrolyte or three-element electrolyte is added in the concentration of 1 mM to 30 mM. 
     
     
         8 . The droplet control apparatus according to  claim 2 , wherein if the material added in the droplet is neutral, the two-element electrolyte or three-element electrolyte is added in a concentration of 1 mM to 100 mM. 
     
     
         9 . The droplet control apparatus according to  claim 8 , wherein if the material added in the droplet is neutral, the two-element electrolyte or three-element electrolyte is added in the concentration of 10 mM to 30 mM. 
     
     
         10 . The droplet control apparatus according to  claim 2 , wherein if the material added in the droplet has a negative charge or positive charge, the two-element electrolyte or three-element electrolyte is added in a concentration of 30 mM to 150 mM. 
     
     
         11 . The droplet control apparatus according to  claim 10 , wherein if the material added in the droplet has a negative charge or positive charge, the two-element electrolyte or three-element electrolyte is added in the concentration of 30 mM to 100 mM.