Patent Publication Number: US-7896621-B2

Title: Micro pump

Description:
This application claims priority to Korean Patent Application No. 2004-102198, filed on Dec. 7, 2004, in the Korean Intellectual Property Office, and all the benefits accruing therefrom under 35 U.S.C. §119, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a compact fluid system, and more particularly, to a micro pump adoptable to a compact fluid system. 
     2. Description of the Related Art 
     The recent rapid progress of micro machining techniques enables the development of a Micro-Electro Mechanical System (MEMS) having various functions. Such an MEMS is widely used in the fields of genetic engineering, medical diagnoses, drug discovery, and the like. In particular, the performance of all necessary processes including chemical reaction and analysis on a chip, a so-called Lab On a Chip (LOC), is introduced. Thus, an MEMS is more actively studied. 
     A fluid such as a sample, a reagent, or the like, must flow in units of micro-liters to drive such a chip or a compact fluid system. Thus, a drive source is required to flow such a fluid. A micro pump is one such example of a drive source. 
     The micro pump may be a bubble pump, a membrane pump, a rotary pump, or the like. The bubble pump heats a chamber to generate bubbles in a fluid filling the chamber and flows the fluid using a pressure of the bubbles. The membrane pump contracts and compresses the chamber using an electrostatic force to flow the working fluid. The rotary pump rotates a rotator, having a plurality of blades on a circumferential surface thereof, to flow a fluid in and out therefrom. 
     However, each of the above described drive sources have certain disadvantages associated therewith. For example, a bubble pump has a complicated structure and requires a long time to heat a drive fluid for flowing a working fluid. The membrane pump also has a complicated structure and consumes a large amount of energy to generate the electrostatic force. The rotary pump has a complicated structure and a low reliability, and is easily not assembled. It is therefore difficult for the bubble, membrane, and rotary pumps to control a minute flow amount of a working fluid. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present general inventive concept has been made to solve the above-mentioned and other problems, and an aspect of the present general inventive concept is to provide a micro pump having a simple structure. 
     Another aspect of the present general inventive concept is to provide a micro pump capable of reducing energy consumption. 
     Another aspect of the present general inventive concept is to provide a micro pump capable of controlling a minute flow amount of a working fluid. 
     According to an aspect of the present invention, there is provided a micro pump including: a pump chamber including inflow and outflow passages through which a drive fluid flows; a first valve selectively opening and/or closing the inflow passage; a second valve selectively opening and/or closing the outflow passage; and a pump chamber heating and cooling unit heating and/or cooling the pump chamber. 
     The pump chamber heating and cooling unit may include: a pump chamber thermoelectric module coupled to the pump chamber and including sides selectively heated and cooled according to a direction of current supplied thereto; and a pump chamber power supplying unit applying power to the pump chamber thermoelectric module. 
     According to an aspect of the present invention, the first and second valves may be passive valves allowing a flow of a fluid only in one direction. 
     According to another aspect of the present invention, the first valve may include: a first valve chamber contracted or expanded so as to open or close the inflow passage; and a first valve chamber thermoelectric module coupled to the first valve chamber so as to contract or expand the first valve chamber. A side of the first valve chamber facing the inflow passage may be formed of a contractible and expandable thin film. The second valve may include: a second valve chamber contracted or expanded so as to open and/or close the outflow passage; and a second valve chamber thermoelectric module coupled to the second valve chamber so as to contract or expand the second valve chamber. A side of the second valve chamber facing the outflow passage may be formed of a contractible and expandable thin film. 
     According to another aspect of the present invention, there is provided a micro pump including: a pump chamber including inflow and outflow passages through which a drive fluid flows; a pump chamber thermoelectric module of a vertical type attached to the pump chamber; a first valve chamber to which a first valve thermoelectric module of a vertical type is attached and which is contracted and expanded by the first valve thermoelectric module so as to selectively open and/or close the inflow passage; and a second valve chamber to which a second valve thermoelectric module of vertical type is attached and which is contracted and expanded by the second valve thermoelectric module so as to selectively open and/or close the outflow passage. 
     According to still another aspect of the present invention, there is provided a micro pump including: a pump chamber including inflow and outflow passages through which a drive fluid flows; a first valve chamber to which a vertical type thermoelectric module is attached and which is selectively contracted or expanded so as to open or close the inflow passage; a second valve chamber contracted and expanded so as to open or close the outflow passage; and a horizontal type thermoelectric module selectively heating or cooling the pump chamber and the second valve chamber. The horizontal type thermoelectric module may include: a first plate attached to the pump chamber; a second plate attached to the second valve chamber; and a plurality of semiconductors interposed between the first and second plates and electrically connected to one another. Lower surfaces of the first and second valve chambers may be formed of contractible and expandable thin films which are contracted and expanded so as to open or close the inflow and outflow passages. 
     According to yet another aspect of the present invention, there is provided a micro pump including: a pump chamber including inflow and outflow passages; a first valve chamber selectively opening and/or closing the inflow passage; a second valve chamber selectively opening and/or closing the outflow passage; and a horizontal type thermoelectric module heating or cooling the pump chamber and the first and second valve chambers. The horizontal type thermoelectric module may include: a first plate attached to the pump chamber and the first valve; a second plate attached to the second valve chamber; and a plurality of semiconductors interposed between the first and second plates and electrically connected to one another. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above aspects and features of the present invention will be more apparent by describing certain embodiments of the present invention with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic plan view of a micro pump according to an embodiment of the present invention; 
         FIG. 2A  is a cross-sectional view taken along line II-II shown in  FIG. 1 ; 
         FIG. 2B  is an enlarged view of portion E shown in  FIG. 2A ; 
         FIGS. 3A and 3B  are cross-sectional views illustrating the operation of the micro pump shown in  FIGS. 1 and 2A ; 
         FIG. 4  is a schematic exploded perspective view of a micro pump according to another embodiment of the present invention; 
         FIG. 5  is a cross-sectional view taken along line V-V shown in  FIG. 4 ; 
         FIGS. 6A and 6B  are cross-sectional views illustrating the operation of the micro pump shown in  FIGS. 4 and 5 ; 
         FIG. 7  is a schematic exploded perspective view of a micro pump according to still another embodiment of the present invention; 
         FIG. 8  is a cross-sectional view taken along line VIII-VIII shown in  FIG. 7 ; 
         FIGS. 9A and 9B  are cross-sectional views illustrating the operation of the micro pump shown in  FIGS. 7 and 8 ; 
         FIG. 10  is a schematic cross-sectional view of a micro pump according to yet another embodiment of the present invention; and 
         FIGS. 11A and 11B  are cross-sectional views illustrating the operation of the micro pump shown in  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Certain embodiments of the present invention will be described in greater detail with reference to the accompanying drawings. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be also understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present therebetween. 
     In the following description, the same drawing reference numerals are used for like elements in different drawings, for ease of illustration. Specific details included in the description, such as detailed construction and elements, are provided solely to assist in a comprehensive understanding of the invention. Thus, it should be appreciated that the present invention can be carried out without such specific details. Also, certain well-known functions or constructions are not described in detail herein, since they would obscure the invention in unnecessary detail. 
     Hereinafter, a micro pump according to embodiments of the present invention will be described in detail with reference to the attached drawings. 
     Referring to  FIGS. 1 and 2 , a micro pump according to an embodiment of the present invention includes a pump chamber  100 , first and second valves  120  and  140 , a heating and cooling unit  160 , and a controller  180 . Inflow and outflow passages  102  and  104  through which a drive fluid flows in and out are formed at the pump chamber  100 . The first valve  120  selectively opens and/or closes the inflow passage  102 , and the second valve  140  selectively opens and/or closes the outflow passage  104 . The heating and cooling unit  160  heats or cools the pump chamber  100 . 
     The pump chamber  100  has a space which is formed from a barrier rib that is not contracted and which is filled with a drive fluid for driving a working fluid. The drive fluid may be a gas such as air, a volume of which greatly varies depending on the temperature thereof. Alternatively, the drive fluid may be a liquid that generates bubbles and that is not melted with a working fluid R. In the present embodiment, air is illustrated as an example of the drive fluid. The inflow passage  102  through which air flows in is formed on the left side of the pump chamber  100  and is exposed to the air so that an atmospheric pressure is formed. However, in a case where the drive fluid is an additional gas or liquid other than air, the inflow passage  102  is connected to a reservoir (not shown) storing the drive fluid. The outflow passage  104  is formed on the right side of the pump chamber  100 , and is filled with the working fluid R, such as a sample to be analyzed by a biochip or a reagent for analyzing the sample. 
     In the present embodiment, the first valve  120  is a passive valve. Thus, the first valve  120  opens the inflow passage  102  only when the atmospheric pressure is greater than the pressure of the pump chamber  100 . 
     Like the first valve  120 , the second valve  140  is a passive valve that, only when the pressure of the pump chamber  100  is greater than the pressure of the outflow passage  104 , opens the outflow passage  104 . 
     The heating and cooling unit  160  includes a thermoelectric module  162  and a power supplying unit  177  supplying current to the thermoelectric module  162 . 
     As particularly shown in  FIG. 2B , the thermoelectric module  162  includes a first plate  164  which is fixed on a lower surface of the pump chamber  100  by a fixing means such as an adhesive or the like. The thermoelectric module  162  may be a vertical type thermoelectric module contacting the lower surface of the pump chamber  100 . The thermoelectric module  162  also includes a second plate  168  which faces the first plate  164 , and a semiconductor layer  166  which is interposed between the first and second plates  164  and  168 . The semiconductor layer  166  is connected to the power supplying unit  177  so as to be supplied with current, and selectively heats or cools the first and second plates  164  and  168  depending on the direction of the supplied current through Peltier effect heating/cooling of the thermoelectric module  162 . For example, if power is applied to the semiconductor layer  166 , the semiconductor layer  166  absorbs heat from the first plate  164  to cool the first plate  164  and transmits the heat to the second plate  168  so as to heat the second plate  168 . Conversely, if the direction of the current supplied by the power supplying unit  177  is reversed, then the semiconductor layer  166  absorbs heat from the second plate  168  to cool the second plate  168  and transmits the heat to the first plate  164  so as to heat the first plate  164 . Peltier effect devices, such as the thermoelectric module  162 , are well known devices and are thus not described in further detail hereinafter. 
     The controller  180  is connected to the power supplying unit  177  to communicate a signal to the power supplying unit  177  so as to control the direction of the current supplied to the thermoelectric module  162 . 
     The operation of the micro pump shown in  FIG. 1  will now be described with reference to  FIGS. 3A and 3B . 
     Referring to  FIG. 3A , the controller  180  controls the power supplying unit  177  to supply current in a first direction to the thermoelectric module  162 . As a result, the pump chamber  100  is then cooled C, causing the air present in the pump chamber  100  to be condensed. Thus, the pressure of the pump chamber  100  becomes lower than the atmospheric pressure of the inflow passage  102 . As a result, the first valve  120  is opened, and air flows into the pump chamber  100 . 
     Referring to  FIG. 3B , the controller  180  changes the direction of the current supplied to the thermoelectric module  162 . The pump chamber  100  is then heated H, causing the air in the pump chamber  100  to be expanded, thereby increasing the pressure of the pump chamber  100 . As the pressure of the pump chamber  100  becomes greater than the atmospheric pressure, the first valve  120  closes, preventing the continued flow of air from the inflow passage  102  to the pump chamber  100 . As the pressure of the pump chamber  100  continues to increase and exceeds the pressure of the outflow passage  104 , the second valve  140  is opened. The air in the pump chamber  100  then moves toward the outflow passage  104  to flow the working fluid R. 
     The above-described process may be repeatedly performed so as to flow a desired amount of working fluid to a location that utilizes the working fluid. 
     A micro pump according to another embodiment of the present invention will be described with reference to  FIGS. 4 through 6 . 
     Referring to  FIGS. 4 and 5 , in contrast the micro pump according to the previous embodiment, the micro pump according to the present embodiment has a structure in which first and second valves  220  and  240  may be separately controlled. The micro pump includes a pump chamber  200 , the first and second valves  220  and  240 , a heating and cooling unit  260 , and a controller  280 . Inflow and outflow passages  202  and  204  are formed at the pump chamber  200 . The first valve  220  selectively opens and/or closes the inflow passage  202 , while the second valve  240  selectively opens and/or closes the outflow passage  204 . The heating and cooling unit  260  heats or cools the pump chamber  200 . 
     Two supporting parts  210  protrude from each of both sides of an upper surface of the pump chamber  200  so as to fix and support the first and second valves  220  and  240 . Also, first and second channels  206  and  208  are provided so as to form steps with the supporting parts  210 , and the inflow and outflow passages  202  and  204  are respectively formed at the first and second channels  206  and  208  so as to be connected to the pump chamber  200 . The first channel  206  is a passage through which air as a drive fluid flows and which is opened to the atmosphere so as to absorb air. The second channel  208  is a channel through which a working fluid flows and which is connected to a location (not shown) utilizing the working fluid. A pump chamber sensor  214  is installed within the pump chamber  200  to sense physical information of the pump chamber  200 . The physical information sensed by the sensor  214  may be, for example, a parameter such as temperature, pressure, current supplying time, or the like, of the pump chamber  200 . 
     The first valve  220  includes a first valve chamber  222 , a first valve heating and cooling unit  226  for heating or cooling the first valve chamber  222 , and a first valve sensor  232  for sensing physical information of the first valve chamber  222 . 
     The first valve chamber  222  is fixed to the supporting parts  210  by a fixing means such as an adhesive or the like. A lower surface of the first valve chamber  222  is formed of a contractible and expandable thin film  224  so as to be contracted and expanded, depending on the pressure of the first valve chamber  222 . The inflow passage  202  is selectively opened or closed by contracting or expanding the thin film  224 . 
     The first valve heating and cooling unit  226  includes a thermoelectric module  228  of a vertical type and a power supplying unit  230  supplying a current to the thermoelectric module  228 . In contrast to a vertical type thermoelectric module, the opposing plates of a horizontal type thermoelectric module as discussed herein lie in substantially the same plane. The thermoelectric module  228  is attached to an upper surface of the first valve chamber  222  by a fixing means, such as an adhesive or the like, so as to selectively heat or cool the first valve chamber  222 . 
     The first valve sensor  232  is installed inside the first valve chamber  222  to sense physical information of the first valve chamber  222 . 
     The second valve  240  is configured the same as the first valve  220 , in terms of structure and operation principle. In other words, like the first valve  220 , the second valve  240  includes a second valve chamber  242 , a second valve heating and cooling unit  246 , and a second valve sensor  252 . The second valve heating and cooling unit  246  includes a thermoelectric module  248  of vertical type and a power supplying unit  250 . 
     The pump chamber heating and cooling unit  260  includes a thermoelectric module  262  fixed on the lower surface of the pump chamber  200  and a power supplying unit  270  supplying power to the thermoelectric module  262 . 
     The controller  280  is connected to each of the power supplying units  230 ,  250 , and  270 , as well as to the pump chamber sensor  214 , the first valve sensor  232 , and the second valve sensor  252  so as to communicate signals with them. In particular, the controller  280  also controls the power supplying units  230 ,  250 , and  270  so as to be turned on and/or off, along with and directions of currents supplied to the thermoelectric modules  228 ,  248 , and  262 , depending on the physical information sensed by the pump chamber sensor  214 , the first valve sensor  232 , and the second valve sensor  252 . 
     The operation of the micro pump shown in  FIG. 4  will now be described in detail with reference to  FIGS. 6A and 6B . 
     Referring to  FIG. 6A , the controller  280  controls the power supplying units  230 ,  250 , and  270  to supply currents to the thermoelectric modules  228 ,  248 , and  262 , respectively. Due to the polarity of the respective currents applied to the thermoelectric modules  228 ,  248 , and  262 , the pump chamber  200  and the first valve chamber  222  are cooled C, while the second valve chamber  242  is heated H. Since the first valve chamber  222  is cooled C, the thin film  224  of the lower surface of the first valve chamber  222  is contracted. Thus, the outflow passage  204  is opened. On the other hand, the second valve chamber  242  is heated H, and air filling the second valve chamber  242  is expanded. Thus, a thin film  244  of a lower surface of the second valve chamber  242  is expanded. The expansion of the thin film  244  causes the outflow passage  204  to be blocked (closed). Also, since the pump chamber  200  is cooled C, the air in the pump chamber  200  is condensed. Thus, the pressure of the pump chamber  200  is lower than the atmospheric pressure. Air then sequentially passes through the first channel  206  and the inflow passage  202  (being open) so as to flow into the pump chamber  200 . 
     Referring to  FIG. 6B , the controller  280  controls the power supplying units  230 ,  250 , and  270  in a manner so as to change the directions of the currents supplied to the thermoelectric modules  228 ,  248 , and  262 . The pump chamber  200  and the first valve chamber  222  are then heated H, while the second valve chamber  242  is cooled C. Thus, the thin film  224  of the first valve chamber  222  is expanded to close the inflow passage  202 , and the thin film  244  of the second valve chamber  242  is contracted to open the outflow passage  204 . The air in the pump chamber  200  is heated H to increase the pressure of the pump chamber  200 . The increased pressure causes the air to flow out through the outflow passage  204  and the second channel  208 , with the outflowing air moving the working fluid to a place utilizing the same. 
     The pump chamber sensor  214 , the first valve sensor  232 , and the second valve sensor  252  sense the physical information of the pump chamber  200 , the first valve chamber  222 , and the second valve chamber  242 , respectively, and transmit the physical information to the controller  280 . The controller  280  then controls the power supplying units  230 ,  250 , and  270  according to the physical information to control times required for supplying the currents, intensities of the supplied currents, and the like. Degrees of opening the inflow and outflow passages  202  and  204  may be controlled in this manner. For example, specific amounts of air flowing into the pump chamber  200 , flowing out from the pump chamber  200 , and heating in the pump chamber  200  may be individually controlled. A flow amount of the working fluid, a pressure of the working fluid, and the like can also be controlled in this manner. Because a minute flow amount of the working fluid can be controlled, a more precise fluid system is achieved. 
     A micro pump according to still another embodiment of the present invention will now be described in detail with reference to  FIGS. 7 through 9B . The micro pump according to the present embodiment is different from the micro pump according to the previous embodiment in that a thermoelectric module  362  of a horizontal type is used to heat and cool a second valve chamber  342  and a pump chamber  300 . Thus, only parts of a structure of the micro pump according to the present invention different from those of the structure of the micro pump according to the previous embodiment will be described in detail. 
     Referring to  FIGS. 7 and 8 , the horizontal type thermoelectric module  362  is attached to the pump chamber  300  and an upper surface of the second valve chamber  342  by a fixing means such as an adhesive or the like. The thermoelectric module  362  of horizontal type includes a frame  364 , first and second plates  366  and  372  respectively formed at both sides of the frame  364 , a plurality of semiconductors  370  installed on the frame  364  so as to be positioned between the first and second plates  366  and  372 , and a conductor  368  connected to a power supplying unit  374  and connecting the plurality of semiconductors  370 . 
     The first plate  366  is positioned on an upper surface of the pump chamber  300 , and the second plate  372  is attached to the upper surface of the second valve chamber  342 . Thus, when the power supplying unit  374  supplies current to the conductor  368 , one of the first and second plates  366  and  372  is heated, and the other is cooled. As a result, when power is applied to the horizontal type thermoelectric module  362 , one of the pump chamber  300  and the second valve chamber  342  is heated while the other is cooled. Again, the principles of operation of the Peltier effect type thermoelectric module  362  are well known in the art, and thus the detailed description thereof is omitted. As the remaining structural elements of the structure of the micro pump according to the present embodiment are the same as those in the previous embodiment of  FIGS. 4-6 , the detailed description thereof is not repeated. 
     The operation of the micro pump shown in  FIG. 7  will be described in detail with reference to  FIGS. 9A and 9B . 
     Referring to  FIG. 9A , a controller  380  controls power supplying units  330  and  374  to supply current to a first valve (vertical type) thermoelectric module  328  and the horizontal type thermoelectric module  362 . Initially, both the first valve chamber  322  and the pump chamber  300  are cooled C, while the second valve chamber  342  is heated H. Thus, a thin film  324  of the first valve chamber  322  is contracted so as to open an inflow passage  302 , while a thin film  344  of the second valve chamber  342  is expanded so as to close an outflow passage  304 , and air in the pump chamber  300  is condensed so as to lower the pressure of the pump chamber  300 . As a result, air passes through a first channel  306  and the inflow passage  302  so as to flow into the pump chamber  300 . 
     Referring to  FIG. 9B , when the process of flowing air into pump chamber  300  is completed, the controller  380  changes directions of currents supplied to the thermoelectric modules  328  and  362 . Thus, the first valve chamber  322  and the pump chamber  300  are now heated H, while the second valve chamber  342  is cooled C. As a result, the thin film  324  of the first valve chamber  322  is expanded to close the inflow passage  302 , and the thin film  344  of the second valve chamber  342  is contracted to open the outflow passage  304 . Air in the pump chamber  300  is expanded, and the pressure of the pump chamber  300  thus rises. As the pressure of the pump chamber  300  rises, the air in the pump chamber  300  flows out to a second channel  308  through the open outflow passage  304 . The outflowing air allows a working fluid to be displaced and flow to a location utilizing the same. 
     As described above, since the thermoelectric module  362  of horizontal type heats or cools the pump chamber  300  and the second valve chamber  342 , the structure of the micro pump becomes simpler. In addition, since a thermoelectric module of a horizontal type (using the heating or cooling energy of both sides thereof) is used instead of a thermoelectric module of a vertical type (using the heating or cooling energy of only side thereof), the energy consumption thereof is reduced. 
       FIG. 10  is a cross-sectional view of a micro pump according to yet another embodiment of the present invention. 
     Referring to  FIG. 10 , the micro pump according to the present embodiment is different from the micro pump according to the previous embodiment in that a horizontal type thermoelectric module  462  is used to heat or cool first and second valve chambers  422  and  442  and a pump chamber  400 . A first plate  466  is attached to an upper surface of the first valve chamber  422 , as well as to an upper surface of the pump chamber  400 , and a second plate  468  is attached to an upper surface of the second valve chamber  442 . The remaining elements of the micro pump according to the present embodiment are the same as those of the micro pump according to the previous embodiment, and thus their detailed description will be omitted. 
     The operation of the micro pump shown in  FIG. 10  will be described with reference to  FIGS. 11A and 11B . 
     Referring to  FIG. 11A , a controller  480  controls a power supplying unit  474  to supply current to the thermoelectric module  462 . The first plate  466  is then cooled so as to cool both the first valve chamber  422  and the pump chamber  400 . A thin film  424  of the first valve chamber  422  is contracted to open an inflow passage  402 , while air in the pump chamber  400  is cooled C and condensed. Thus, the pressure of the pump chamber  400  drops below the atmospheric pressure. Air then flows into the pump chamber  400  through a first channel  406  due to the difference between the atmospheric pressure and the pressure of the pump chamber  400 . Additionally, the second plate  468  heats the second valve chamber  442  to expand a thin film  444 , which then closes an outflow passage  404 . 
     Referring to  FIG. 11B , when the controller  480  changes the direction of the current supplied to the thermoelectric module  462 , the first plate  466  is then heated while the second plate  468  is cooled. Correspondingly, the first valve chamber  422  and the pump chamber  400  are heated H, and the second valve chamber  442  is cooled C. As a result, the thin film  424  of the first valve chamber  422  is expanded so as to close the inflow passage  402 . On the other hand, the thin film  444  of the second valve chamber  442  is contracted so as to open the outflow passage  404 . Also, since the air in the pump chamber  400  is expanded, the pressure of the pump chamber  400  rises, eventually to a level above atmospheric pressure. At this point, the air in the pump chamber  400  flows out to a second channel  408  through the open outflow passage  404 . The outflowing air moves a working fluid to a location utilizing the same. As described above, the thermoelectric module  462  is used to heat or cool the first and second valve chambers  422  and  442  and the pump chamber  400 . Thus, unnecessary energy consumption can be reduced, and the structure of the micro pump can become simpler. 
     As described above, in a micro pump according to an embodiment of the present invention, a pumping operation may be repeatedly performed. Also, the structure of the micro pump can be simpler. As a result, a subminiature fluid system can be easily adopted to the micro pump. 
     In addition, the degree of opening and closing of the inflow and outflow passages can be regulated. Moreover, the degree of heating a drive fluid of the pump chamber can also be controlled. This in turn allows a minute flow amount of a working fluid to be controlled. As a result, a more precise fluid system can be embodied. 
     Furthermore, a thermoelectric module can be used to rapidly control the condensation and an expansion of air in the pump chamber. Thus, the response time of the micro pump can be improved with respect to conventional designs. 
     Also, because a horizontal type thermoelectric module can be used to open and/or close a valve and provide a driving force for the pumping working of the pump chamber, the structure of the pump chamber can be simpler. In addition, heated or cooled heat can be re-used, resulting in the reduction of energy consumption. 
     An air pressure can be used as the drive fluid. Thus, a higher pressure can be generated to flow the working fluid. 
     The foregoing embodiment and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. Also, the description of the embodiments of the present invention is intended to be illustrative, and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.