Method of fabricating bubble-type micro-pump
A manufacturing method of a bubble-type micro-pump is provided. At least a bubble-generating unit is provided on the bubble-generating section. Because of the varied surface energies on the top of the bubble-generating section, the varied backfilling velocities of the fluid of the front end and the rear end cause fluid moving when a bubble vanishes. The top surface of the bubble-generating section is subjected to a particular surface treatment to form a surface energy gradient. Examples of surface treatment include sputtering a thin film with varied densities or thickness, radiating one or multi-layer thin films by a laser beam, etc.
1. A method of fabricating a bubble-type micro-pump, comprising:
providing a micro-channel having a top surface, a bottom surface and two side walls, the micro-channel comprising at least a bubble-generating section;
providing a bubble-generating unit in the bubble-generating section of the micro-channel, for generating a bubble in a liquid between a front end and a rear end of the bubble-generating section; and
applying a surface treatment to the top surface of the bubble-generating section to form a surface energy gradient on the top surface, so that a difference between a backfilling velocity at the front end and that at the rear end drivers the liquid to flow toward the front end or the rear end;
wherein at least two regions with different surface energies are formed by sputtering form forming the surface energy gradient on the top surface;
wherein a step of forming the surface energy gradient on the top surface comprises:
sputtering a film on the top surface of the bubble-generating section, and the thickness of the film gradually increasing or decreasing from the front end to the rear end; and
sputtering the film on the top surface in the bubble-generating section, and the density of the film gradually increasing or decreasing from the front end to the rear end.
2. The method according to claim 1 , wherein the step of forming the surface energy gradient on the top surface comprises:
sputtering a first film in a first region on the top surface adjacent to the front end of the bubble-generating section, the first film having a first surface energy; and
sputtering a second film in a second region on the top surface adjacent to the rear end of the bubble-generating section, the second film having a second surface energy and connected to the first film, wherein the first surface energy is different from the second surface energy.
3. The method according to claim 1 , wherein the step of providing the micro-channels comprises:
providing a first substrate and a second substrate, the first substrate comprising at least a recess having the bubble-generating section; and
attaching the first substrate and the second substrate, wherein the surface of the recess forms the top surface and the two walls of the micro-channel, and surface of the second substrate forms the bottom surface of the micro-channel.
4. The method according to claim 3 , wherein the step of providing the bubble-generating unit comprises:
disposing a first electrode and a second electrode on the bottom surface in the bubble-generating section, the first electrode and the second electrode respectively adjacent to the front end and the rear end of the bubble-generating section.
5. The method according to claim 3 , wherein the first substrate is manufactured by a disc manufacturing process.
6. The method according to claim 3 , wherein the first substrate with the recess is manufactured by injection molding, pressure casting or etching.
7. The method according to claim 3 , wherein the first substrate and the second substrate are attached by a pressure sensitive adhesive.