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Loop-type microfluidic systemRelated Patent Categories: Pumps, Motor Driven, Electric Or Magnetic Motor, Collapsible Wall Pump, Diaphragm Type, Of Semiconductor Material (e.g., Silicon, Germanium, Etc.)Loop-type microfluidic system description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060280629, Loop-type microfluidic system. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The present invention is related to a microfluidic system, particularly to a loop-type microfluidic system utilizing a micro loop-channel. BACKGROUND OF THE INVENTION [0002] With the development of technology, the biochip controlled by the computer could implement various biochemical reactions conventionally operated by hands. Such biochip may even handle the complicated microfluidic operation. [0003] Generally, the microfluidic operation may be applied to the polymerase chain reaction (PCR). It could exactly find out specific base sequence with hundreds of base pairs from the nucleic acid molecule with millions of base pairs, and reproduce this sequence for more than one million times. The process of PCR mainly comprises three steps which repeat sequentially. First, in the step of denature, the temperature is raised to 95.degree. C. so that the double strand structure of the DNA template would be opened. Next, in the step of annealing, the temperature is declined to 50-60.degree. C. so that a pair of primers would enter the DNA molecule to mount in the position of the base pair. Finally, in the step of extension, the temperature is raised to 65-75.degree. C. to activate the polymerase and form a new double strand nucleic acid molecular sequence. [0004] By repeating the above three steps, the polymerase chain reaction is performed for DNA amplification. Usually, the PCR performed by conventional machine would cost about three hours. However, with the development of the micro machining processes, the substrate could be etched to form the microfluidic channels thereon. In addition, the copper piece with constant temperature could be applied as the thermal source to form a biochip for biochemical reaction. This kind of biochip has small size, fast cycle speed and tiny requirement of specimen. The biochip could further coupled to the electrophoresis chip to form a DNA analysis system. [0005] Recent researches mainly focus on the improvement of the heating material, the size of the micro channel, the material of the substrate or the cycle times of the PCR chip. The main principles are similar and only the unidirectional movement is applied. This kind of design should modify the length of the channel according to the reaction times. Generally, about thirty times of reaction are preferably required, and therefore the longer micro-channel is necessary. Besides, the times of reaction could not be adjusted at one's own choice to obtain the best result. [0006] Conventionally, the microfluidic movement device merely utilizes linear direction. For example, TW Patent No. 499302 filed on Nov. 5, 2001, entitled "A system and method for driving microfluid by air," disclosed the manipulation of the air pressure to make the microfluid move forward and backward repeatedly. TW Patent No. 528836 filed on Jun. 9, 1999, entitled "Method and device for driving microfluid," disclosed the air-driven microfluidic reciprocation system and temperature controller for biochemical reaction. Such techniques could merely be applied to simple biochemical reaction, rather than complicated biochemical or chain reaction. Especially for PCR, the temperature of the microfluid should be changed repeatedly and quickly. Consequentially, if the aforementioned conventional techniques are applied to PCR, the difficult temperature change control would be necessary, and then the experiment or reaction may become much more complicated. [0007] Additionally, referring B. C. Giordano, J. Ferrance, S. Swedberg, A. F. R. Huhmer, and J. P. Landers, "Polymerase Chain Reaction in Polymeric Microchips: DNA Amplification in Less Than 240 Seconds," Anal Biochemistry 291, PP. 124-132, 2001, the specimen is placed in the chamber of the biochip, and the temperature controller would modify the temperature to obtain the cycles of three-level temperature change. Although the times of reaction could be determined on one's demand, the fast temperature control is complex and difficult. [0008] The prior art also provides the microfluidic thermal cycle system which enables the microfluid moving forward and backward. However, the fast temperature change is still required, even though the length of channel is shortened and the reaction times can be adjusted by the user. [0009] Followings are other related reference: (1) Capillary electrophoresis (CE) chip, developed by Harrison et al. who proposed a complex manifold of capillary channels fabricated in glass substrate using micromachining techniques, see Harrison, D. J., Manz, A., Fan, Z., Ludi, H. and Widmers, H. M., Anal. Chem. 64, 1926 (1992)); (2) Polymerase chain reaction (PCR) microchip, designed by Kopp et al., on which the sample was controlled to flow continuously in an unidirectional channel through three thermostated temperature zones to complete a total of 20-cycle PCR amplification, see Kopp, M. U., Mello, A. J. and Manz, A., Science. 280, 1046 (1998); (3) Flow switch, investigated by Lee et al., for continuous 1.times.N sample switching and injection based on microfluidic phenomena of hydrodynamic focusing and valveless flow switching, see Lee, G. B., Hung, C. I., Ke, B. J., Huang, G. R. and Hwei, B. H., J. Micromech. Microeng. 11, 567 (2001); (4) Integrated microfluidic devices, for example, Bums et al. developed a microfabricated device having the fluidic channels, heaters, temperature sensors, and fluorescence detectors for DNA analysis, see Bums, M. A., Johnson, B. N., Brahmasandra, S. N., Handique, K., et al., Science. 282, 484 (1998); Yokoyama et al. investigated thermal-bubble type micropump with loop-type micro channel for cooling purpose, see Yokoyama, Y., Takeda, M., Umemoto, T. and Ogushi, T., Sensors and Actuators, A111, 123 (2004). Kang et al. developed a radial grooved micro heat pipes allowing separation of the liquid and vapor flow in a three-layer structure which was fabricated on silicon wafer using bulk micromachining, see Kang, S. W., Tsai, S. H. and Chen, H. C., Applied Thermal Engineering, 22, 1559 (2002). The most common and evolved techniques for microfluid driving include on-chip micropump and external driving source. Zengerle et al. developed a micropump actuated by electrostatic for bidirectional driving, see Zengerle, R., Ulrich, J., Kluge, S., Richter, M. and Richter, A., Sensors and Actuators A50, 81 (1995); Hartly patented his invention on peristaltic micropump, see Hartley, F. T., U.S. Pat. No. 5,705,018 (1998); Piezoelectric valveless micropump was designed by Olsson et al., see Olssen, A., Stemme G. and Stemme, E., Sensors and Actuator A47, 549 (1995); Jen et al investigated a bidirectional microfluid driving system by suction and exclusion controlled from external servo system, see Jen, C. P. and Lin, Y. C., J. Micromech, Microeng, 12, 115 (2002). [0010] In conclusion, the conventional microfluidic driving and movement devices merely allow the microfluid move in linear direction. If one-way movement is adopted, longer micro-channel would be required. Thus, the frequency of malfunction is highly raised, and the reaction times are unchanged. Micro-chamber and reciprocation PCR chip may modify the number of cycles, but the necessary temperature change control would also complicate the manipulation of chain reaction. SUMMARY OF THE INVENTION [0011] In view of the aforementioned problems, the present invention therefore provides a loop-type microfluidic system and device. The microfluid within the loop-channel could be driven to circle around repeatedly, and the temperature controllers may control the temperature of each segment of the loop-channel so that the microfluid would undergo one time of three-level temperature change in each circle. With the control of the circling times, the preferred times of reactions would be performed to obtain accurate result. [0012] One purpose of the present invention is proving a loop-type microfluidic system which comprises a loop-channel for allowing the microfluid moving therein, plural air holes for allowing the entrance or the drain of the air or the microfluid, and plural driving conduits for allowing the air or the microfluid passing through. One end of each driving conduit is connected to the loop-channel and the other end is connected to one of the air holes. The air supply is coupled to the air holes for enabling the entrance or drain of the air so as to drive the microfluid within the loop-channel. At least one temperature controller is coupled to the loop-channel to control the temperature of the microfluid within the loop-channel. [0013] Another purpose of the present invention is providing a loop-type microfluidic device, which comprises a loop-channel for allowing the microfluid moving therein, plural air holes for allowing the entrance or the drain of the air or the microfluid, and plural driving conduits for allowing the air or the microfluid passing through. One end of each diving conduit is connected to the loop-channel and the other end is connected to one of the air holes. BRIEF DESCRIPTION OF THE DRAWINGS [0014] FIG. 1 is the schematic structure diagram illustrating the loop-type microfluidic device according to the preferred embodiment of the present invention. [0015] FIG. 2 is the three-dimensional schematic diagram of the loop-type microfluidic biochip. [0016] FIG. 3 is a system block diagram illustrating the loop-type microfluidic system, according to the preferred embodiment of the present invention. [0017] FIG. 4 illustrates the process for driving the microfluid in the loop-channel. [0018] FIG. 5 is the flow chart of the process for driving the microfluid. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0019] The present invention is described with the preferred embodiments and accompanying drawings. It should be appreciated that all the embodiments are merely used for illustration. Although the present invention has been described in terms of various preferred embodiments, the invention is not limited to these embodiments. The scope of the invention is defined by the claims. Modifications within the spirit of the invention will be apparent to the person having ordinary skill in the art. Continue reading about Loop-type microfluidic system... 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