Microfluidic valve unit for controlling flow of fluid and method of fabricating the same
A microfluidic valve unit for controlling the flow of fluid flowing along a channel, and a method of fabricating the same are provided. The valve unit includes a channel formed in a platform; a valve filler which includes a phase transition material that is disposed in the channel in a solid state at room temperature to close the channel and is melted when energy is applied thereto; and at least one capillary channel which extends from a sidewall of the channel and into which the valve filler flows when the valve filler is melted, wherein the at least one capillary channel has a cross-sectional area which is less than a cross-sectional area of the channel.
1. A valve unit comprising:
a channel formed in a platform, wherein the channel comprises a protrusion portion having a first channel depth, and channel groove portions disposed on opposite sides of the protrusion portion and having a second channel depth which is greater than the first channel depth so that the protrusion portion forms a step with respect to the channel groove portions;
a valve filler which comprises a phase transition material that is disposed and hardened in the protrusion portion of the channel in a solid state at room temperature to close the channel and is melted when energy is applied thereto; and
at least one capillary channel which extends from a sidewall of the protrusion portion of the channel and into which the valve filler flows when the valve filler is melted, wherein the at least one capillary channel has a cross-sectional area which is less than a cross-sectional area of the channel.
2. The valve unit of claim 1 , further comprising a ventilation hole formed at an end of the at least one capillary channel,
wherein the ventilation hole is opened while the valve filler is melted.
3. The valve unit of claim 1 , further comprising an injection hole through which the valve filler is injected into the channel.
4. The valve unit of claim 3 , wherein the injection hole is closed after the valve filler is injected into the channel.
5. The valve unit of claim 1 , wherein the at least one capillary channel comprises a plurality of capillary channels formed on both of two opposite sidewalls of the channel or one of the two opposite sidewalls of the channel.
6. The valve unit of claim 1 , wherein the phase transition material of the valve filler comprises wax, gel, or thermoplastic resin.
7. The valve unit of claim 6 , wherein the wax comprises at least one selected from the group consisting of paraffin wax, microcrystalline wax, synthetic wax, and natural wax.
8. The valve unit of claim 6 , wherein the gel comprises at least one selected from the group consisting of polyacrylamide, polyacrylates, polymethacrylates, and polyvinylamides.
9. The valve unit of claim 6 , wherein the thermoplastic resin comprises at least one selected from the group consisting of cyclic olefin copolymer (COC), polymethylmethacrylate (PMMA), polycarbonate (PC), polystyrene (PS), polyoxymethylene (POM), perfluoralkoxy (PFA), polyvinylchloride (PVC), polypropylene (PP), polyethylene terephthalate (PET), polyetheretherketone (PEEK), polyamide (PA), polysulfone (PSU), and polyvinylidene fluoride (PVDF).
10. The valve unit of claim 1 , wherein the valve filler further comprises a plurality of minute heating particles which are dispersed in the phase transition material and emit heat by absorbing energy.
11. The valve unit of claim 10 , wherein the minute heating particles comprise particles of a metal oxide.
12. The valve unit of claim 11 , wherein the metal oxide comprises at least one selected from the group consisting of Al 2 O 3 , TiO 2 , Ta 2 O 3 , Fe 2 O 3 , Fe 3 O 4 , and HfO 2 .
13. The valve unit of claim 10 , wherein the minute heating particles comprise polymer particles, quantum dots, or magnetic beads.