Abstract:
A multiplexer for controlling a fluid in a microchannel by controlling pneumatic pressure in the microchannel in a microfluidics chip includes: a first pneumatic channel; and a second pneumatic channel forming a cross point which is in communication with the first pneumatic channel, wherein the cross point is in communication with the microchannel of the microfluidics chip, and predetermined pneumatic pressure is provided to the microchannel by using a combination of providing of the pneumatic pressure to the first and second pneumatic channels, channel closing, or channel opening.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2016-0045560, filed on Apr. 14, 2016 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0002]    The present invention relates to a multiplexer capable of controlling a fluid in a microchannel of a microfluidics chip and a microfluidics chip assembly including the same. 
       2. Description of the Related Art 
       [0003]    A microfluidics chip may be called Lab-on-a-chip (LOC) and can analyze a profile in which while a small quality of materials to be analyzed flow, the materials react with various biomolecules or sensors aggregated in a chip. In recent years, application fields of the microfluidics chip have been widened primarily to separation, synthesis, quantitative analysis, and the like of an analyzed material. 
         [0004]    Meanwhile, as a method for controlling a flow of fluids in the microchannel of the microfluidics chip, a pneumatic valve using a transformable member is generally used and in detail, the flow of the fluids in the microchannel positioned below the membrane can be selectively interrupted blocked through expansion of the membrane. As one example, Korean Patent Unexamined Publication No. 2012-0056055 discloses a micro valve controlling the quantity of sample channels by expanding a thin polymer membrane. 
         [0005]    However, when the thin polymer membrane is used as the pneumatic valve, a life-span of the pneumatic valve itself is limitative and the pneumatic valve has a limit in use due to direct contact with fluids in a channel, and the like. 
         [0006]    Further, as the pneumatic valve selectively interrupting the channel, that is, the membrane needs to the channel one to one and a solenoid valve generating a pneumatic pressure needs to be connected to each channel, and the like, a manufacturing method or manufacturing cost of the micro valve is significant and controlling the flow of the fluids is significantly complicated because the channel needs to be controlled one to one. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides a multiplexer and a microfluidics chip assembly including the same, which can exclude a separate membrane selectively interrupting a microchannel of a microfluidics chip and control a flow of fluids in the microchannel to solve various problems in use and manufacturing, such as a limit in life-span or a process of forming a membrane. 
         [0008]    The present invention selectively interrupts the flow of the fluids in the microfluidics chip only by a pneumatic pressure. 
         [0009]    The present invention provides a multiplexer and a microfluidics chip assembly including the same, which can respective microchannels only with less solenoid valves than the microchannels without arranging a pneumatic valve and a solenoid valve for controlling the microchannels provided in the microfluidics chip one to one to implement simplification of a manufacturing process and saving of manufacturing cost through the simplification of the manufacturing process. 
         [0010]    An exemplary embodiment of the present invention provides a multiplexer for controlling a fluid in a microchannel by controlling pneumatic pressure in the microchannel in a microfluidics chip, including: a first pneumatic channel; and a second pneumatic channel forming a cross point which is in communication with the first pneumatic channel, wherein the cross point is in communication with the microchannel of the microfluidics chip, and predetermined pneumatic pressure is provided to the microchannel by using a combination of pneumatic pressing, channel closing, or channel opening to the first and second pneumatic channels. Namely, the user can control the pneumatic pressure provided to the first and second pneumatic channels by selecting one from a group of pneumatic pressure providing, channel closing and channel opening, and the predetermined pneumatic pressure provided to the microchannel can be controlled by using the above combination. 
         [0011]    Another exemplary embodiment of the present invention provides a multiplexer for controlling a fluid in a microchannel by providing pneumatic pressure into a microchannel of a microfluidics chip, including: a first lamination plate having a first pneumatic channel; and a second lamination plate having a second pneumatic channel and a cross point where the second pneumatic channel crosses the first pneumatic channel to form the cross point to be in communication with each other, wherein while the microfluidics chip vertically overlaps with the first and second lamination plates, the microchannel is in communication with the cross point, and as a result, when the pneumatic pressure is provided to any one side of first and second pneumatic channels, loss of the pneumatic pressure to the other side occurs and only when the pneumatic pressure is provided to both the first and second pneumatic channels or the pneumatic pressure is provided to any one side of the first and second pneumatic channels and the other side is closed, the pneumatic pressure may be provided to the microchannel. When the pneumatic pressure is provided to the microchannel, a concentration gradient for a reagent in the microchannel may be implemented or reaction of a reaction object depending on a type or a concentration of the reagent may be verified. 
         [0012]    Selective interruption of the microchannel is implemented by using not a separate thin film but only the pneumatic pressure, and as a result, a complicated process for generating a membrane is omitted, thereby reducing manufacturing cost. 
         [0013]    Further, when air pressure is provided to any one side of the first and second pneumatic channels, pressure leaks to the other side and the pneumatic pressure is provided to both the first and second pneumatic channels to control the fluid in the microchannel of the microfluidics chip, and as a result, an external device (e.g., a solenoid valve) for providing the pressure need not be disposed to correspond to the microchannel one to one and the manufacturing cost can be reduced and the number of complicated external devices can be minimized, thereby enabling a high-density screening test. 
         [0014]    In detail, a multiplexer may be provided, in which two or more of M first pneumatic channels and N second pneumatic channels separated from each other are provided and each second pneumatic channel includes branch channels branched to correspond to the number M of first pneumatic channels and when the branch channel forms a cross point with the first pneumatic channel, at least M*N microchannels may be controlled by using M+N first and second pneumatic channels. For example, when each second pneumatic channel includes the branch channels of the same number as the first pneumatic channels, the pneumatic pressure may be provided independently to M*N microchannels by using M+N first and second pneumatic channels. 
         [0015]    The multiplexer may be simply manufactured by sequentially laminating the first lamination plate and the second lamination plate on the top of the microfluidics chip having the microchannel in the related art. 
         [0016]    As a detailed example for connecting the microchannels and the pneumatic channels formed on the laminated chip or plate, the first pneumatic channel, the second pneumatic channel, and the microchannel may be provided to the first lamination plate, the second lamination plate, and the microfluidics chip, respectively in a groove shape and the second pneumatic channel may be partially provided in a hole shape at the cross point to be in communication with the first pneumatic channel and the microchannel may also be in communication at the cross point. Differently, the second pneumatic channel may vertically penetrate the second lamination plate and the first pneumatic channel and the microchannel may be provided on the bottom of the first lamination plate and the top of the microfluidics chip, respectively in the groove shape toward the second pneumatic channel. 
         [0017]    Further, appropriate through-holes may be formed on the first and second lamination plates in order to provide air pressure to the first pneumatic channel of the first lamination plate and the second pneumatic channel of the second lamination plate disposed between the second lamination plate and the microfluidics chip. For example, a first through-hole for providing the pneumatic pressure to the first pneumatic channel and a second through-hole for providing the pneumatic pressure to the second pneumatic channel of the second lamination plate may be formed in the first laminate plate. 
         [0018]    In the case of the first and second lamination plates of the multiplexer, a pattern for forming the pneumatic channel or the through-hole may be carved and a synthetic resin such as polydimethylsiloxane (PDMS) may be provided through a photography or spin coating method. 
         [0019]    The above described multiplexer is laid on the microfluidics chip to control the fluid in the microchannel by using only the pneumatic pressure without a separate membrane. 
         [0020]    In a microfluidics chip in the related art, a separate thin member is used for selective interruption of a microchannel, and as a result, a complicated membrane generation process is added and the membrane is limited in life-span in a thin synthetic resin form and the membrane may directly contact a drug in the microchannel in actual use. However, in the case of a multiplexer and a microfluidics chip assembly adopting the same, since only pneumatic pressure may can serve as a valve that controls a fluid in the microchannel without using the membrane, and as a result, a complicated process is omitted, thereby reducing manufacturing cost. 
         [0021]    Further, in the case of the multiplexer and the microfluidics chip assembly adopting the same, only when the pneumatic pressure is applied to both first and second pneumatic channels connected with the microchannels or the pneumatic pressure is provided to any one of the first and second pneumatic channels and the other side is closed, the pneumatic pressure can serve as an opened valve and when air pressure is provided to any one side of the first and second pneumatic channels, the air pressure serves as a closed valve to cause the pressure to leak to the other side, and as a result, a solenoid valve need not be disposed in the microchannel one to one, therefore, the manufacturing cost can be reduced and the number of complicated external devices can be minimized, thereby enabling a high-density sorting inspection. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a perspective view of a microfluidics chip assembly according to an exemplary embodiment of the present invention. 
           [0023]      FIG. 2  is an exploded perspective view of the microfluidics chip assembly.  FIG. 3  is a schematic structural diagram of a pneumatic channel and a microchannel for describing that air is selectively injected into the microchannel of a microfluidics chip by using a multiplexer. 
           [0024]      FIG. 4  illustrates a microfluidics chip assembly capable of controlling (M*N) microchannels by using (M+N) pneumatic channels according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]    Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited or restricted to the exemplary embodiments. For reference, in the description, like reference numerals substantially refer to like elements, which may be described by citing contents disclosed in other drawings under such a rule and contents determined to be apparent to those skilled in the art or repeated may be omitted. 
         [0026]      FIG. 1  is a perspective view of a microfluidics chip assembly according to an exemplary embodiment of the present invention.  FIG. 2  is an exploded perspective view of the microfluidics chip assembly and  FIG. 3  is a schematic structural diagram of a pneumatic channel and a microchannel for describing that air is selectively injected into the microchannel of a microfluidics chip by using a multiplexer. 
         [0027]    Referring to  FIGS. 1 to 3 , the microfluidics chip assembly  100  according to the exemplary embodiment includes a multiplexer  130  and a microfluidics chip  140 . 
         [0028]    The multiplexer  130  is formed by laminating two lamination plates and microchannels  141  are formed in the microfluidics chip  140  provided in a plate type like the lamination plate. 
         [0029]    The plates are preferably made of glass or silicones and synthetic materials which less react with acid or base or other biochemical materials. In particular, polymethylsiloxane may be used and the materials as polymer materials which may be bonded to each other may implement a stable tight contact state between the plates and although described later in detail, plates having the pneumatic channels or the microchannels provided a shape of a groove dug on the surface of the plate with a predetermined depth, such as a groove or a hole penetrating the plate tightly contact each other to effectively maintain a sealing state of the channels. 
         [0030]    First, the multiplexer  130  has a first lamination plate  110  and a second lamination plate  120  and a first pneumatic channel  111  is formed on the first lamination plate  110 . The first pneumatic channel  111  is provided in the groove shape formed on the surface of the first lamination plate  110 . In addition, a second pneumatic channel  121  is formed on the second lamination plate  120  and the second pneumatic channel  121  may also be provided in the groove shape formed on the surface of the second lamination plate  120 . However, the first and second pneumatic channel  111  and  121  need to be in communication with each other at a cross point  123  and a part of the second pneumatic channel  121  may be thus provided in the hole shape vertically penetrating the second lamination plate  120  at the cross point  123 . 
         [0031]    The first and second lamination plates  110  and  120  of the multiplexer  130  are laid on the microfluidics chip  140  and during this process, the microchannels  141  formed in the microfluidics chip  140  may be in communication with the cross point  124  formed by the first and second pneumatic channel  111  and  121 . 
         [0032]    As seen in  FIGS. 1 to 3 , in the case of a lamination order, the first lamination plate  1110 , the second lamination plate  120 , and the microfluidics chip  140  are sequentially laminated from the top to the bottom and a second through-hole  114  for providing a pneumatic pressure to the second pneumatic channel  121  of the second lamination plate  120  disposed below the first lamination plate  110  penetrates the first lamination plate  110  and similarly, a first through-hole  112  for providing the pneumatic pressure to the first pneumatic channel  111  is formed. 
         [0033]    Through the multiplexer  130 , the pneumatic pressure may be provided to the microchannels  141  of the microfluidics chip  140  disposed to tightly contact the bottom of the multiplexer  130 . The pneumatic pressure is provided to the microchannels  141  of the microfluidics chip  140  to serve as a pneumatic valve and perform even basic function to analyze a profile in which a small quantity of materials to be analyzed flows to the microchannels to reach with various biomolecules or sensors aggregated in the chip. 
         [0034]    In particular, the first pneumatic channel  111  and the second pneumatic channel  121  of the multiplexer  130  of the present invention are in communication with each other at the cross point  123  and due to such a reason, when the pneumatic pressure is provided to any one side, the pneumatic pressure leaks to the other side. This is illustrated in detail in  FIG. 3  and in detail, the case is illustrated in  FIG. 3C . Of course, a predetermined amount of pneumatic pressure may flow in the microchannels  141 , but this may be appreciated that a reagent or a specimen in the microchannels  141  or only very little pneumatic pressure not to serve as the pneumatic valve is transferred. 
         [0035]    That is, it is easy to transfer pneumatic pressure at a designed level to the microchannels  141  only when the pneumatic pressure is provided to both the first and second pneumatic channels  111  and  121  as illustrated in  FIG. 3A . For reference, in  FIG. 3B , illustrated is a case where the pneumatic pressure is provided to only any one side of the first and second pneumatic channels  111  and  121 , but the other side is closed, and as a result, the pneumatic pressure is provided to the microchannels  141 . 
         [0036]    Meanwhile, air provided to the pneumatic channels is controlled through the solenoid valve and the air is provided to the pneumatic channels or the aforementioned closing state is implemented by operating an on/off state of the solenoid valve. For reference, the air is preferably nitrogen which is inert gas, but a type of the air is appropriately selected by the reagent or specimen and is not limited to the nitrogen and the valve may also be replaced with another device which may selectively provide/interrupt external gas to the pneumatic channels and is not limited only to the aforementioned solenoid valve. 
         [0037]    Meanwhile, in the related art, the solenoid valves need to be disposed in all microchannels one to one in order to provide the pneumatic pressure to the microchannels, and as a result, it is difficult to miniaturize a facility and a high-density screening test itself is difficult. 
         [0038]    However, the solenoid valves need not be disposed in the microchannels one to one by using the multiplexer  130  according to the present invention and manufacturing cost may be reduced and the miniaturization of the facility may be implemented. 
         [0039]    Referring to  FIGS. 1 or 2 , the multiplexer  130  has the first lamination plate  110  having three first pneumatic channels  111  and the second lamination plate  120  having two second pneumatic channels  121 . 
         [0040]    Further, the second pneumatic channels  121  is branched into a plurality of branch channels  122  and the number of branch channels  122  is provided to correspond to the number of first pneumatic channels  111 . Herein, the “correspond” means that when the number of branch channels  122  is larger than the number of first pneumatic channels  111 , branch channels not connected to the first pneumatic channels are present, and as a result, the number of branch channels included in one second pneumatic channel may be provided to be equal to or less than the total number of first pneumatic channels. 
         [0041]    In the exemplary embodiment, the number of branch channels  122  included in each second pneumatic channel  121  is three similarly to the number of first pneumatic channels  111 . Accordingly, only 5 solenoid valves which is the sum total of 3 which is the number of first pneumatic channels  111  and 2 which is the number of second pneumatic channels  121  are connected to the first and second through-holes  112  and  114  to selectively provide the pneumatic pressure and may control each of 6 branch channels  122  which is a multiplication of the number of first pneumatic channels  111  and the number of second pneumatic channels  121  and individually control the microchannels  141  connected to the branch channels  122 . 
         [0042]    When the exemplary embodiment is generalized, as illustrated in  FIG. 4 , two or more of M first pneumatic channels  111  and N second pneumatic channels  121  separated from each other are provided and each second pneumatic channel  121  includes branch channels  122  branched to correspond to the number M of first pneumatic channels  111  and the branch channel  122  forms the cross point with the first pneumatic channel  111 . In this case, the multiplexer  130  may be provided, which may control at least M*N microchannels  141  by using M+N first and second pneumatic channels  111  and  121 . In detail, when it is assumed that each second pneumatic channel  121  includes branch channels  122  of the same number as the first pneumatic channels  111 , the pneumatic pressure may be provided independently to the respective M*N microchannels  141  by using M+N first and second pneumatic channels  111  and  121 . 
         [0043]    The present invention has been described with reference to the preferred embodiments of the present application. However, it will be appreciated by those skilled in the art that various modifications and changes of the present invention can be made without departing from the spirit and the scope of the present invention which are defined in the appended claims and their equivalents.