Apparatus and method for improved electrostatic drop merging and mixing

A method for merging and mixing a first droplet and a second droplet on an apparatus having a substrate;

• a first originating electrode, a center electrode, and a second originating electrode, wherein each of the electrodes is disposed on the substrate such that the first originating electrode and the second originating electrode are on opposite sides of the center electrode, and wherein a first gap is formed between the first originating electrode and the center electrode, and a second gap is formed between the center electrode and the second originating electrode, the first gap having a width less than a cross-sectional diameter of the first droplet, and the second gap having a width less than a cross-sectional diameter of the second droplet;
• and a dielectric layer disposed adjacent to the substrate and covering the first originating electrode, the center electrode, and the second originating electrode;
• comprising:
• depositing the first droplet across the first gap;
• depositing the second droplet across the second gap;
• and
• applying a first potential across the first originating electrode and the center electrode, and a second potential across the second originating electrode and the center electrode, wherein the first potential operates on the first droplet causing the first droplet to move toward the second droplet, and the second potential operates on the second droplet, causing the second droplet to move toward the first droplet, such that the first droplet and the second droplet move toward each other and collide and mix together.

A method for merging and mixing a first droplet and a second droplet on an apparatus having a substrate, a first electrode and a second electrode disposed on the substrate such that a gap is formed between the first electrode and the second electrode, the gap having a width less than the cross-sectional diameter of the first droplet;

• and a dielectric layer disposed on the substrate and covering the electrodes;
• the method comprising:
• depositing the first droplet asymmetrically across the gap;
• depositing the second droplet on top of the second electrode;
• and
• applying a potential between the first electrode and the second electrode, wherein the potential causes the first droplet to move towards the second droplet and to overshoot a symmetric position across the gap such that the first droplet collides and mixes with the second droplet.

A method for merging and mixing a first droplet and a second droplet on an apparatus having a substrate, a first electrode and a second electrode disposed on the substrate such that a gap is formed between the first electrode and the second electrode, the gap having a width less than the cross-sectional diameter of the first droplet;

• and a dielectric layer disposed on the substrate and covering the electrodes;
• the method comprising:
• depositing the first droplet, wherein at least a portion of the first droplet is located on a portion of the first electrode and a portion of the second electrode, and another portion of the first droplet is located off of the first electrode and the second electrode;
• depositing the second droplet, wherein at least a portion of the second droplet is located on a portion of the first electrode and a portion of the second electrode, and another portion of the second droplet is located off of the first electrode and the second electrode and wherein the first droplet and the second droplet are separated from each other;
• and
• applying a potential between the first electrode and the second electrode, wherein the potential causes the first droplet to move towards the second droplet and causes the second droplet to move towards the first droplet such that the gap is parallel to the movement of the droplets and the first droplet and the second droplet collide and merge with each other.