Abstract:
An apparatus for driving microfluids is provided. The apparatus comprises a driving unit and a microfluidic chip. The driving unit comprises a substrate and a film, wherein the film is combined with the substrate. Moreover, the microfluidic chip is coupled with the driving unit.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to an apparatus for driving the microfluid and the method thereof, and more particularly to an apparatus for driving the microfluid and the driving method thereof with the driving unit and the microfluidic system chip (or called the microfluidic chip) being manufactured separately.  
       BACKGROUND OF THE INVENTION  
       [0002]     In recent decades, the microfluidic technology utilized in biomedical studies becomes popular because of the development and maturity of the Micro-electro-mechanical-systems. Whether the concept of Micro Total Analysis System (μTAS) for performing complex biochemical and/or chemical analyses on a microsystem chip or the concept of the Lab-on-a-chip for lessening the manipulations of a traditional lab on a chip are both developed based upon the integration of microfluidic technology. The relevant components including the microchannel, microprocessor, microvalve, micromixer, microseparator and fluid-driving unit are developed according to the characteristics of the microfluid. The fluid-driving technology plays a crucial role that although the microfluidic chip has the capacity of lessening an experimental process onto a microchip, the microfluid cannot be transmitted if it does not cooperate with an appropriate fluid-driving method. Besides, different kinds of microfluids would not interact with each other or work in accordance with the requests of the chips, and thus the desired purpose would not be achieved.  
         [0003]     The microfliud-driving methods can be roughly divided into two types, the non-mechanical one and the mechanical one with a movable configuration. The major characteristic of non-mechanical type is to integrate the microfluidic driving unit into a microfluidic chip and input a voltage or a current into the internal electrode of the chip to generate the electrokinetic force, electromagnetic force or pneumatic force to drive the working fluids. The characteristic of these methods lies in that the chip does not include the movable configuration therein so that they have the advantages of high reliability and good stability. Furthermore, the microfliud-driving unit constructed on the chip directly would not have the problem of coupling with the microchip. Considering these driving methods, the required operating power or voltage is usually huge and is only suitable for few fluids, and the electric property, the pH value and the electrolyte of the fluid need to be considered.  
         [0004]     On the contrary, the mechanical type is not usually limited by the properties of the fluids. The mechanical type often needs a movable configuration included therein for operation, e.g. the flexible-plane-wave type which utilizes the interdigital electrode to create a plane wave on the piezoelectric substrate and push the fluid to move forward through the transmission of the plane wave. Otherwise, a mechanically movable unit, e.g. a movable film, is utilized to apply a pneumatic, a piezoelectric, an electrostatic or an electromagnetic force thereon for driving, and through the movement of the film, a pneumatic force is generated to press the air cell for driving. Please refer to  FIG. 1 , which is a structural diagram of U.S. Pat. No. 6,227,809. As shown in  FIG. 1 , a driver  44  indigenously integrated on the chip is used to periodically press a vibratable film  46  covering the chamber  24 , and a fluidic diode is cooperatively used therewith to push the flow to move unidirectionally. Since the driver is directly mounted on the microfluidic chip, the manufacturing cost of the microfluidic chip increases relatively and the processes thereof are more complicated because of the compatibility, even decreasing the possibility of serving as the disposable chip.  
         [0005]     Therefore, the method of separating the power source is brought up, wherein the major characteristic thereof is to separate the microfluid-driving unit from the microfluidic chip, and through the coupling therebetween, the physical change generated by the microfluid-driving unit is transmitted to the microfluidic chip to avoid some problems of the chip manufacturing cost, the processing compatibility and the limitation of fluids caused by the integrated method. Please refer to  FIG. 2 , which is a structural diagram of U.S. Patent Publication No. 2004/0063217. As shown in  FIG. 2 , an additional linear driver  20  is used to press a flexible mid-layer  23  to achieve the purposes of pressing the chamber and driving the fluid. Although this method is advantageous for separating the chip and the driving device, the cost, the volume and the control of the linear driver are still complicated. Moreover, the chip integrated with a film usually attends the problems as the increase of the manufacturing cost and the decrease of the yield.  
         [0006]     Keeping the drawbacks of the prior arts in mind, and employing experiments and researches full-heartily and persistently, the applicant finally conceived the apparatus for driving the microfluid and the driving method thereof.  
       SUMMARY OF THE INVENTION  
       [0007]     This application seeks to provide an apparatus and a method to drive a microfluid, which purposes ameliorating the various limitations of the current microfluid-driving configurations such as the manufacturing cost, the processing compatibility of the microfluidic chip and the limitation of the working fluids in use. The feature of the present invention lies in that the driving unit is manufactured separately from the microfluidic system chip to avoid the problems derived from constructing the driving unit on the microfluidic system chip. In the meantime, the mechanically moveable elements with highly manufacturing cost, such as a moveable film, designed in the driving unit can achieve the requests for decreasing the cost and increasing of the yield under the situation of the microfluidic system chip including no moveable structures. The driving unit and the microfluidic system chip are coupled with a flexible film existing in the driving unit, possessing the features of softness and conformal coverage, which enables rapid and temporary coupling of the driving unit with the microfluidic system chip during operation, and is advantageous for simplifying the coupling problem substantially and keeping well gastight effect to enable the pressure generated by the driving unit to be transmitted effectively to the microfluidic system chip. Besides, through the design of a partially film-movable area which can be operated multiply in accordance with different requests, the air cell generated by temporarily coupling is pressed or pulled so that a pressure change is generated to drive the working fluid. The microfluidic system chip does not include any moveable elements and/or power sources so that the apparatus for driving the microfluid and the driving method thereof are advantageous for low cost and disposability. Furthermore, the apparatus further has the advantages of small volume, simple design, easy operation and being programmable.  
         [0008]     An aspect of the present invention is related to an apparatus for driving the microfluid comprising a driving unit and a microfluidic chip. The driving unit includes a film and a substrate, wherein the film is combined with the substrate, and the microfluidic chip is coupled with the driving unit. The coupling between the microfluidic chip and the driving unit can be made by any known coupling devices. The driving unit coupled with the microfluidic chip generates a temporarily gastight joint therebetween.  
         [0009]     The driving unit further comprises an aperture passing through the substrate. A first portion of the film covering the aperture is a film-movable area because the film is flexible and exposed due to the aperture passing through the substrate. A second portion of the film covering the substrate without the aperture is a film-immovable area. The movable-film area cooperates with the film-driving device to drive the film. The principle of the driving device can be selected from a group consisting of electromagnetic type, electrostatic type, piezoelectric type, thermal expansion type, phase change type, and a combination thereof. The driving device controlled by electricity can perform the single cyclic, the reciprocated and the programmable operations to cause a driving deformation of the film, which results in pressing the air cell formed via gastightly jointing the film. A barometric change is then generated to drive the microfluid and control the position of the microfluid. It can also be operated multiply in accordance with different requests.  
         [0010]     Preferably, the apertured substrate can be replaced with a substrate having a cavity.  
         [0011]     The microfluidic chip further comprises a base having a cavity structure with an opening corresponding with the film-movable area, wherein the microfluidic chip coupled with the driving unit generates the pressure source for driving the microfluid by changing the volume of the air cell formed via gastightly jointing the film and the microfluidic chip. Besides, the microfluidic chip further comprises a stop valve which generates various fluid-controlled effects by cooperating with the driving unit. The stop valve is one selected from a group consisting of a shape stop valve, a material stop valve and a combination thereof.  
         [0012]     Another aspect of the present invention is related to an apparatus for driving the microfluid comprising a microfluidic chip and a driving unit. The microfluidic chip comprises plural opening configurations as a fluid injection cavity, a pressure cavity and an opening connected by plural channels, wherein the plural channels are opened channels and/or closed channels. The opened channel means that the channel is exposed in the air when the microfluidic unit and the driving unit are uncoupled therebetween, while the closed channel means that the channel exists in the microfluidic chip and is unexposed in the air. The driving unit comprises a film and a substrate, wherein the driving unit is coupled with the microfluidic chip. The coupling between the microfluidic chip and the driving unit can be made by any known feeding mechanisms. The feeding mechanisms are included in the driving unit and comprise a linearly movable platform to provide a moving toward function, a coupled position holding function and a returning function for coupling the driving unit and the microfluidic chip. The driving unit is coupled with the microfluidic chip to generate a temporarily gastight joint therebetween.  
         [0013]     The film can be adhered to the substrate which has been perforated by micromachining or other machining techniques. Also, the substrate can be perforated by micromachining or other machining techniques after the film is adhered thereto to make the film expose. Because the film is flexible, the exposed film caused by the aperture on the substrate is a film-moveable area which is corresponding to the position of the pressure cavity on the microfluidic chip, and the portion of the film covering the substrate without the aperture is a film-immoveable area. The film-driving device is disposed in the film-movable area for driving the film. The driving device controlled by electricity can perform the single cyclic, the reciprocated and the programmable operations to cause a driving deformation of the film, which results in pressing or pulling the air cell formed via gastightly joint the film so as to generates a barometric change to drive the microfluid. The barometric change can accurately control the position of the microfluid and can be operated multiply in accordance with different requests.  
         [0014]     The microfluidic chip is made of a material selected from a group consisting of a PMMA, a PC, an SU-8, a TEFLON, a PDMS, a glass, a silicon chip, a metal and a combination thereof. The substrate of the driving unit uses a material with higher hardness selected from a group consisting of a glass, a silicon chip, a PDMS, a metal and a combination thereof. The film of the driving unit uses a flexible material with lower hardness such as a PDMS.  
         [0015]     A further aspect of the present invention is related to a method for driving the microfluid. The method includes the following steps: (a) providing a microfluidic chip comprising plural channels and plural opening configurations including a fluid injecting cavity, a pressure cavity and an opening, wherein the opening configurations are connected by the plural channels; (b) providing a driving unit comprising a film, an apertured substrate, a film-driving device for the film and a feeding mechanism, wherein a first portion of the film covers the aperture and a second portion of the film covers the substrate without the aperture, wherein the first portion is a film-movable area, and the second portion is a film-immovable area; (c) dropping a working fluid into the fluid injecting cavity; (d) coupling the driving unit and the microfluidic chip by the feeding mechanism to generate a temporarily gastight joint, where a closed air cell is formed between the film-movable area and the pressure cavity, and the film-immovable area seals the opening configurations except the pressure cavity and the opening; and (e) using the film-driving device to cause a deformation of the film-movable area, to change a pressure of the closed chamber, and to drive the working fluid to flow from a high-pressure area to a low-pressure area.  
         [0016]     The pressure cavity can be used as a fluid injection cavity, and the working fluids can be injected therein to raise the compression ratio of the air cell to increase the barometrically driving power of the driving fluids.  
         [0017]     The pressure can also be reduced by expanding the volume of the air cell to generate a negative pressure to drive the working fluid to flow from a high-pressure area to a low-pressure area.  
         [0018]     The driving unit and the microfluidic system chip in the present invention are designed separately and coupled with the conventional coupling device, so all of the working fluids would not directly contact the driving unit or contaminate reciprocally with the chip so that the driving unit can be used repeatedly. On the other hand, the microfluidic system chip does not include any moveable elements and/or power sources so it has the advantages of low cost and disposability. The size of the driving unit matches the microfluidic system chip, so the efficiency of driving is enhanced, and the volume and the manufacturing and operation cost of the elements is decreased. Besides, the present invention is simple for operation. The user just needs to inject the working fluids into the fluid injecting cavity of the chip and it can work with the driving unit without any other process, and the chip is easy to be separated from the driving unit after work. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]      FIG. 1  is a structural diagram of U.S. Pat. No. 6,227,809;  
         [0020]      FIG. 2  is a structural diagram of U.S. Patent Publication No. 2004/0063217;  
         [0021]      FIG. 3  is a schematic diagram showing the structure of the system in the present invention;  
         [0022]     FIGS.  4 ( a )- 4 ( c ) show the working principle for driving the microfluid according to a preferred embodiment of the present invention; and  
         [0023]     FIGS.  5 ( a )- 5 ( c ) show the working principle for driving the microfluid according to another preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]     In order to further illustrate the techniques, methods and efficiencies used to procure the aims of this invention, please see the following detailed description. It is believable that the features and characteristics of this invention can be deeply and specifically understood by the descriptions. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for the purposes of illustration and description only; it is not intended to be exhaustive or to be limited to the precise form disclosed.  
         [0025]     Please refer to  FIG. 3 , which is a schematic diagram showing the structure of the system in the present invention. The system comprises a driving unit  1  and a microfluidic chip  2 , wherein the driving unit  1  comprises a film  7  and a substrate  12  covered by the film  7 . A portion of the substrate  12  is removed which causes the film  7  to be exposed, forming a film-moveable area  3 . The portion except the film-moveable area  3  is a film-immoveable area. The microfluidic chip comprises a pressure cavity  4  corresponding to the film-moveable area  3 , a fluid injection cavity  5  not corresponding to the film-moveable area  3 , and an opening  6 , wherein the pressure cavity  4 , the fluid injection cavity  5  and the opening  6  are connected with each other by the channels  11 . To drive the microfluid, it needs to couple the driving unit  1  with the microfluidic  2  by a coupling device.  
         [0026]     Please refer to  FIG. 4 ( a )- 4 ( c ), which show the working principle for driving the microfluid according to a preferred embodiment of the present invention. As shown in  FIG. 4 ( a ), the driving unit  1  comprises the film  7 , the film-moveable area  3  and a driver  8  mounted on the film-moveable area  3 . The working fluids  9  are injected into the microfluidic chip  2  via the fluid injection cavity  5 , wherein the microfluidic chip  2  comprises the pressure cavity  4 , the fluid injection cavity  5 , the working fluids  9  and a shape valve  10 .  
         [0027]     As shown in  FIG. 4 ( b ), the driving unit  1  is coupled with the microfluidic chip  2  by a coupling device. Because the film  7  is flexible, the coupling between the driving unit  1  and the microfluidic chip  2  would generate a gastight joint between the film-moveable area  3  and the pressure cavity  4  so that the pressure cavity  4  is sealed thereby. Besides, the film-immoveable area would seal the fluid injection cavity  5 , which causes partial microfluidic channels to be closed.  
         [0028]     As shown in  FIG. 4 ( c ), the driver  8  is driven to generate a deformation of the film  7  of the film-moveable area  3 . Since a closed space is formed in the pressure cavity, the deformation of the film will change the volume of the pressure cavity  4 , which increases the pressure therein. Therefore, the working fluids are pressed to move toward the low-pressure area so that the aim for driving the microfluids is procured. For controlling the working fluids  9 , the shape valve  10  can be disposed in the microfluidic channels so that the working fluids  9  may stop at an appropriate position for conforming to the conditions, e.g. the required time, the volume and the concentration, of the reaction or measurement.  
         [0029]     Please refer to FIGS.  5 ( a )- 5 ( c ), which show the working principle for driving the microfluid according to another preferred embodiment of the present invention. The pressure cavity  4  of the present invention can be used for injecting the working fluids  9  to raise the compression ratio of the air cell so that the barometrically driving power for driving the fluids is increased. As shown in  FIG. 5 ( a ), the driving unit comprises the film  7 , the substrate covered with the film  7 , the film-moveable area  3  and the driver  8  mounted on the film-moveable area  3 . The working fluids  9  is injected into the microfluidic chip  2  via the pressure cavity  4 , wherein the microfluidic chip  2  comprises the pressure cavity  4 , the working fluids  9  and the shape valve  10 .  
         [0030]     As shown in  FIG. 5 ( b ), the driving unit  1  is coupled with the microfluidic chip  2  by a coupling device. Because the film  7  is flexible, the coupling therebetween would generate a gastight joint between the film-moveable area  3  and the pressure cavity  4  to seal the pressure cavity  4 , thereby sealing partial microfluidic channels in the microfluidic chip  2 .  
         [0031]     As shown in  FIG. 5 ( c ), the driver  8  is driven to generate a deformation of the film  7  of the film-moveable area  3 . Since a closed space is formed in the pressure cavity, the deformation of the film will change the volume of the pressure cavity  4 , which increases the pressure therein. Hence, the working fluids are pressed to move toward the low-pressure area so that the aim for driving the microfluids is procured. For controlling the working fluids  9 , the shape valve  10  can be disposed in the microfluidic channels so that the working fluids  9  may stop at an appropriate position for conforming to the conditions, e.g. the required time, the volume and the concentration, of the reaction or measurement.  
         [0032]     While the invention has been described in terms of what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention need not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims, which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures. Therefore, the above description and illustration should not be taken as limiting the scope of the present invention which is defined by the appended claims.