Abstract:
Eccentrically actuated microvalves and micropumps. Microfluidic channels are formed in multi-layered laminar assemblies with at least one layer including an elastomeric material. In some embodiments, the microvalves and micropumps are controlled by eccentrically driven actuators, including in some embodiments cam-driven actuators. A cam-driven actuator activates a microvalve by pressing on the elastomeric layer, deforming the elastomeric layer so that it meets a second layer at a location within the channel, thereby either partially or completely obstructing the flow of liquid through the channel at that location, i.e. “pinching” the channel. The actuator is moved into position by a cam, which includes detents that allow the actuator to move away from the first layer or raised areas that force the actuator to move toward the first layer. Some embodiments include multiple microvalves, in which case a single cam, controlled by a single position-control mechanism, is able to control multiple microvalves. The resulting apparatuses are useful for controlling multi-channel microfluidic systems in an energy-efficient and space-efficient manner.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not Applicable 
       STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of Invention 
         [0004]    The present invention relates generally to microscale devices for performing analytical testing and, in particular, to valves and pumps for use in microscale chemistry. 
         [0005]    2. Description of the Related Art 
         [0006]    Mircofluidic devices have in recent years found increased application for performing analytical tasks in a number of fields. Particularly in various chemical, biological, and biomedical disciplines, microfluidic systems allow complicated biochemical reactions to be carried out using very small volumes of liquid and small samples of reagents. In these applications microfluidic devices are often constructed in a multi-layer laminated assembly that defines microscale channels or in structures formed from laminate material. In this context, a microscale channel is generally defined as a fluid passage which has at least one internal cross-sectional dimension that is less than 900 micrometers. 
         [0007]    Many types of valves and pumps for use in directing and controlling fluids in microfluidic environments are known in the art. Typical of the art in this field are U.S. Pat. No. 5,899,437, issued on May 4, 1999 to Quarre; U.S. Pat. No. 6,068,751, issued May 30, 2000 to Neukermans; U.S. Pat. No. 6,102,068, issued Aug. 15, 2000 to Higdon et al.; U.S. Pat. No. 6,143,248, issued Nov. 7, 2000 to Kellogg; U.S. Pat. No. 6,581,899, issued Jun. 24, 2003 to Williams; U.S. Pat. No. 6,619,311, issued Sep. 16, 2003 to O&#39;Connor et al.; U.S. Pat. No. 6,626,417, issued Sep. 30, 2003 to Winger et al.; U.S. Pat. No. 6,739,576, issued May 25, 2004 to O&#39;Connor et al.; U.S. Pat. No. 6,748,975, issued Jun. 15, 2004 to Hartshorne et al.; U.S. Pat. No. 6,802,489, issued Oct. 12, 2004 to Marr et al.; U.S. Pat. No. 6,929,030, issued Aug. 16, 2005 to Unger et al.; U.S. Pat. No. 7,144,616, issued Dec. 5, 2006 to Unger et al.; U.S. Pat. No. 7,258,774, issued Aug. 21, 2007 to Chou et al.; and U.S. Pat. No. 7,601,270, issued Oct. 13, 2009 to Unger et al. Also typical of the art in this field are a utility patent application by O&#39;Conner et al., published Oct. 23, 2003 as U.S. Patent Pub. No. 2003/0196695; and a utility patent application by Unger et al., published Jul. 24, 2008 as U.S. Patent Pub. No. 2008/0173365. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    Disclosed are microvalves and micropumps for use with a microfluidic system. In some embodiments, the microvalves and micropumps are controlled by eccentrically driven actuators, including in some embodiments cam-driven actuators. In some embodiments, the microfluidic system includes at least one channel incorporated into a laminar structure. The laminar structure includes at least two layers: a first layer fabricated from an elastomer or similar material, and a second layer fabricated from a material that is either rigid, substantially rigid, flexible, or elastic. The two layers cooperatively define a channel formed by an extended indentation in a surface of the first layer, the second layer, or both layers. One surface of the first layer faces one surface of the second layer, with the channel on at least one of the facing surfaces. The said one surface of the first layer and the said one surface of the second layer largely adhere to one another, with the channel between the two layers through which fluid is able to flow. In some embodiments, the two layers are held together by pressure; in some embodiments, an adhesive substance coats at least part of one or both facing surfaces at the places where the two surfaces touch; in some embodiments, the two surfaces are anodically bonded; in other embodiments, the two surfaces are fused with heat; in still other embodiments, some other surface treatment is used to bond the two layers to each other. 
         [0009]    In one embodiment of the present invention, a cam-driven actuator activates a microvalve by pressing on the elastomeric first layer, deforming the first layer so that the first layer and the second layer meet at a location within the channel, thereby either partially or completely obstructing the flow of fluid through the channel at that location (i.e. “pinching” the channel). The actuator is moved into position by a cam, which includes detents that allow the actuator to move away from the first layer or raised areas that force the actuator to move toward the first layer. Although the present invention contemplates many types of cam-driven actuators, in one preferred embodiment the actuator comprises one or more actuator balls, which are displaced by a cam to deform the elastomeric first layer. 
         [0010]    Cam-driven pinch-style microvalves are useful for serving as on/off valve devices for a microfluidic system. Additionally, some embodiments of the present invention include one or more of these cam-driven pinch-style microvalves to form multifunction devices, including but not limited to distribution valves, switching valves, peristaltic pumps, and other devices. In some embodiments, two or more of the above devices are combined to work with integrated fluidic circuits. 
         [0011]    In some embodiments, the cam is driven and directed by a position-control mechanism, which is electrically powered, hydraulically powered, pneumatically powered, or manually powered, depending on the embodiment. In those embodiments that include multiple microvalves or multifunction devices, the cam-driven microvalves allow a single position-control mechanism, operating in conjunction with a single cam, to control multiple microvalves. The ability to use a single position-control mechanism and a single cam to control multiple microvalves allows for the multi-state positioning of the microvalves with minimal space requirements and minimal control complexity. Further, unlike, for example, flow-control mechanisms that rely on the application of electric currents to cause and sustain physical displacement, cam-driven pinch-style microvalves are capable of generating high compressive forces that do not require additional energy to be sustained. Also, flow-control mechanisms that rely on the application of electric currents to cause electrokinetic flow only function with charged fluids or fluids containing electrolytes; cam-driven pinch-style microvalves and micropumps according to the present invention are usable with a wider variety of fluids. 
         [0012]    Cam-driven pinch-style microvalves are useful for controlling multi-channel microfluidic systems with an energy-efficient and space-efficient apparatus. Thus, these microvalves have uses in a number of diverse fields and applications, including medical and scientific instrumentation, remotely controlled machines such as space probes and undersea probes, and portable analytical equipment for use in the field. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The above-mentioned features of the invention will become more clearly understood from the following detailed description of the invention read together with the drawings in which: 
           [0014]      FIG. 1  is a block diagram representation of one embodiment of the invention; 
           [0015]      FIG. 2  is a perspective view of one embodiment of the invention; 
           [0016]      FIG. 3  is an exploded view of the embodiment shown in  FIG. 2 ; 
           [0017]      FIG. 4A  is a top-down view of the embodiment shown in  FIG. 2 , showing the section line used for the section view shown in  FIGS. 5A and 5B ; 
           [0018]      FIG. 4B  is a top-down view of the embodiment shown in  FIG. 2 , showing the section line used for the section view shown in  FIGS. 6A and 6B ; 
           [0019]      FIG. 5A  is a section view of the embodiment shown in  FIG. 2 , showing the microvalve in an open state; 
           [0020]      FIG. 5B  is a section view of the embodiment shown in  FIG. 2 , showing the microvalve in a closed state; 
           [0021]      FIG. 6A  is a section view of the embodiment shown in  FIG. 2 , showing the microvalve in an open state; 
           [0022]      FIG. 6B  is a section view of the embodiment shown in  FIG. 2 , showing the microvalve in a closed state; 
           [0023]      FIG. 7  is a section view of one embodiment of the invention utilizing multiple actuator balls for one microvalve; 
           [0024]      FIG. 8  is a perspective view of one embodiment of the invention, showing the use of the invention to operate a distribution valve; 
           [0025]      FIG. 9  is a top-down view of the embodiment shown in  FIG. 8 ; 
           [0026]      FIG. 10A  is a section view of the embodiment shown in  FIG. 8 , with a first microvalve pinched and a second microvalve other open; 
           [0027]      FIG. 10B  is a section view of the embodiment shown in  FIG. 8 , with the first microvalve open and the second microvalve other pinched; 
           [0028]      FIG. 10C  is a section view of the embodiment shown in  FIG. 8 , with both microvalves open; 
           [0029]      FIG. 11  is a perspective view of one embodiment of the invention, with one cylindrical cam controlling several actuator balls and several microvalves in a microfluidic system; 
           [0030]      FIG. 12  is a view of the embodiment shown in  FIG. 11 , with an inset view of part of the apparatus; 
           [0031]      FIG. 13  is a perspective view of one embodiment of the invention with a rotary cam; 
           [0032]      FIG. 14  is an exploded view of the embodiment shown in  FIG. 13 ; 
           [0033]      FIG. 15  is a perspective view of one embodiment of the invention with a plate cam; 
           [0034]      FIG. 16  is an exploded view of the embodiment shown in  FIG. 15 ; 
           [0035]      FIG. 17  is a perspective view of one embodiment of the invention, showing a cam-driven peristaltic pump; 
           [0036]      FIG. 18  is an exploded view of the embodiment shown in  FIG. 17 ; 
           [0037]      FIG. 19  is a top-down view of the embodiment shown in  FIGS. 17 and 18 , with the second layer removed; 
           [0038]      FIG. 20A  a top-down view of the embodiment shown in  FIGS. 17 ,  18  and  19 , with the first layer and the second layer removed; 
           [0039]      FIG. 20B  a top-down view of the embodiment shown in  FIGS. 17 ,  18 ,  19 , and  20 A, with the first layer and the second layer removed, where the cam has been rotated from the state seen in  FIG. 20A ; 
           [0040]      FIG. 21A  is a section view of the embodiment shown in  FIGS. 17 ,  18 ,  19 ,  20 A, and  20 B, showing the cam in the position seen in  FIG. 20A ; and 
           [0041]      FIG. 21B  is a section view of the embodiment shown in  FIGS. 17 ,  18 ,  19 ,  20 A,  20 B, and  21 A, showing the cam in the position seen in  FIG. 20B . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0042]    A microfluidic system including a microvalve that uses eccentrically driven actuators to control fluid flow by pinching the channels at selected locations along the length of the channels is described herein with reference to the drawings. 
         [0043]      FIG. 1  is a block diagram of one embodiment of a microvalve according to the present invention. The eccentrically actuated, cam-driven microvalve  10  includes a multilayer channel member  12 , an actuator  51 , a cam  61 , and a position-control mechanism (PCM)  71 . The multilayer channel member  12  includes a first layer  21 , fabricated from an elastomeric material, and a second layer  31 , which is either rigid, substantially rigid, flexible, or elastic. The first layer  21  and the second layer  31  cooperate to define at least one channel  41 . An actuator  51  works with a cam  61  to pinch the channel  41  and restrict the flow of fluid. The cam  61  is driven by the PCM  71  between a first position and a second position. In the first position, the cam  61  causes the actuator  51  to move in an eccentric motion to press the first layer  21  against the second layer  31  in a substantially fluid-tight fit to substantially close the channel  41 . In the second position, the cam  61  does not cause the actuator  51  to engage the first layer  21 , allowing the elastomeric first layer  21  to retract from the second layer  31  and allow fluid to flow through the open channel  41 . In some embodiments, the cam-driven microvalves include a disposable component, such as an interchangeable multi-layer channel member that may be discarded after one use or multiple uses. 
         [0044]      FIG. 2  shows a perspective view of one embodiment of the present invention. The microvalve  101  includes a first layer  201  fabricated from an elastomeric material, and a second layer  301 , which is either rigid, substantially rigid, flexible, or elastic. As seen clearly in the exploded view in  FIG. 3 , a channel  401  has been formed between the first layer  201  and the second layer  301  by forming an extended indentation in the surface of the second layer  301 . One of skill in the art will appreciate that various methods exist for manufacturing the channel  401  in the second layer  301 , including molding, etching, extruding, milling and other processes. In some embodiments, the second layer  301  is molded, and the shape of the channel  401  is included in the mold; in some embodiments, the channel  401  is carved out of the second layer  301  after that layer  301  has been fabricated. In some embodiments, the channel is formed by manufacturing an extended indentation in the first layer, or in both layers. In various embodiments, the two layers are held together by pressure or by a bonding solution. 
         [0045]    As shown in the exploded view of the embodiment in  FIG. 3  and in the sectional views in  FIGS. 5A and 6A , a cam  601  is positioned near the first layer  201 . Between the cam  601  and the first layer  201  is an actuator ball  501  positioned in close proximity to a place where the channel  401  runs on the other side of the first layer  201 . The cam  601  in this embodiment is a cylindrical cam; rotation of the cylinder moves a detent  631  on the cylinder into and out of position under the actuator ball  501 . A position-control mechanism (PCM)  701  controls the cam  601  by turning the axle  651 , thereby turning the cylindrical cam  601 . In various embodiments, the PCM  701  is electrically powered, hydraulically powered, pneumatically powered, or manually powered, depending on the embodiment. In some embodiments, the PCM  701  is a single electric gear motor, which can be turned on and off to rotate the cylindrical cam  601  into the desired position. 
         [0046]    A guide tube  551  partially surrounds the actuator ball  501 , keeping the actuator ball  501  in place between the cam  601  and the first layer  201  by preventing it from travelling with the detent  631  as the cylinder cam  601  rotates. In some embodiments, the actuator ball is kept in place between the cam and the first layer by a guide plate (i.e., a substantially rigid layer of material between the cam and the elastomeric first layer) defining a guide aperture through which the actuator ball moves closer to and away from the first layer. 
         [0047]    When the microvalve  101  is in the open state, as in the sectional views of  FIGS. 5A and 6A , fluid flows through the channel  401  from, for instance, a fluid storage container  431  and fluid input tube  433 , shown in  FIGS. 2 and 3 . When the cam  601  is rotated, so that the actuator ball  501  no longer rests in the detent  631  of the cam  601 , then the actuator ball  501  moves within the guide tube  551  toward the elastomeric first layer  201 , as shown in  FIGS. 5B and 6B . With the cam  601  and the actuator ball  501  now in position to effect the closed state of the microvalve  101 , the actuator ball  501  pushes on the first layer  201 , deforming the elastomeric first layer  201  so that the first layer  201  and the second layer  301  meet within the channel  401 , thereby partially or completely stopping the flow of fluid through the channel  401  (i.e., “pinching” the channel). 
         [0048]    In the embodiment shown in  FIGS. 2 ,  3 ,  4 A,  4 B,  5 A,  5 B,  6 A, and  6 B, the actuator mechanism (that is, the mechanism that pinches the two layers  201  and  301  together to close the microvalve  101 ) comprises a single actuator ball  501 . However, other arrangements are possible, as in the embodiment shown in  FIG. 7 , in which the microvalve  101   a  includes two actuator balls  501   a  and  502   a.  Those of skill in the art will recognize that other arrangements exist for connecting the actuator to the first layer, including balls, pins, or linkages; the arrangement used in a specific embodiment often is selected to accommodate specific packaging requirements. Other actuator arrangements are also contemplated by this invention. 
         [0049]      FIG. 8  shows a perspective view of one embodiment of the present invention in which two cam-driven pinch-style microvalves operated by one cam work in coordination to form a two-way distribution valve.  FIG. 9  shows a top-down view of the same embodiment. As seen in  FIG. 8 , the microfluidic system  108  includes a second layer  308  with three connected channels: the input channel  411 , the first distribution channel  412 , and the second distribution channel  413 . As seen in the section view in  FIG. 10A , this microfluidic system  108  includes a cylindrical cam  608  and two actuator balls  512  and  513 . The actuator ball  512  is positioned to pinch channel  412 , and the actuator ball  513  is positioned to pinch channel  413 . In this embodiment, the cylindrical cam  608  has a number of detents, which allow for multiple settings of the actuator balls  512  and  513 . In the first setting, seen in  FIG. 10A , the first actuator ball  512  is resting in a detent, while the second actuator ball  513  is not in a detent and therefore is pinching the second channel  413 . With the second channel  413  in the closed state, the fluid from the input channel  411  flows through the first distribution channel  412 . In the second setting, seen in  FIG. 10B , the cam  608  has been rotated so that now the second actuator ball  513  is resting in a detent, while the first actuator ball  512  is not in a detent and therefore is pinching the first channel  412 . With the first channel  412  in the closed state, the fluid from the input channel  411  flows through the second distribution channel  413 . Finally, in the third setting, seen in  FIG. 10C , the cam  608  has been rotated yet again so that now both actuator balls  512  and  513  are resting in detents, and both distribution channels  412  and  413  are in an open state. 
         [0050]      FIG. 11  shows a microfluidic system incorporating a plurality of microvalves according to one embodiment of the present invention. The apparatus  111  includes multiple microvalves that operate to regulate the flow of fluids in a microfluidic system; all of the microvalves are controlled by a single cam  611  adapted to work with multiple actuator balls  511   a - d.  As shown in  FIG. 11 , and as shown in the inset in  FIG. 12 , the apparatus  111  includes a plurality of fluid storage vessels  436   a - d.  These fluid storage vessels  436   a - d  are in fluid communication with a mixing vessel  446 . A main channel  422  connects the mixing vessel  446  with a number of side channels  424   a - d,  each side channel  424   a - d  leading to a fluid storage vessel  436   a - d.  As in the previously illustrated embodiments, the apparatus  111  includes a first layer  211  and a second layer  311 . 
         [0051]    The main channel  422  and the side channels  424   a - d  are carved into the second layer  311  and comprise fluid-passable passages between the first layer  211  and the second layer  311 . (It should be noted that, in  FIGS. 11 and 12 , the second layer  311  is fabricated from a clear plastic or similar material, which allows an observer to see the channels from the exterior of the apparatus. However, in some embodiments of the invention, the channels may not be visible from the outside, depending upon the material from which the second layer is fabricated.) 
         [0052]    A cylinder cam  611  with multiple detents, e.g.,  631   a - d,  is positioned below the elastomeric first layer  211 . Actuator balls  511   a - d  are positioned between the cam  611  and the first layer  211 . A drive belt  710  connects the cam  611  to a PCM  712 , which includes a control pad  714  to allow an operator to direct the PCM  712 . In some embodiments, the PCM is a single motor, which spins the drive belt  710  to turn the cylinder cam  611 . The various components of the apparatus  111  are held together by a housing  813 , which includes guide slots which hold the actuator balls  511   a - d  in place, and a glass or plastic sub-housing  811  to protect the fluid storage vessels  436   a - d  and the mixing vessel  446 . 
         [0053]    As the cam  611  rotates about its central axis, different detents will come into position below certain of the actuator balls, opening the microvalves leading to different fluid storage vessels. The illustrated apparatus  111  allows for a number of settings in with differing combinations of open and closed microvalves. Thus, for example, in the illustrated embodiment, the detents  631   a  and  631   c  lie along the same longitudinal line on the cylinder cam  611  (this longitudinal line being shown by a dashed line in  FIG. 11 ). When the cam  611  rotates so that the detents  631   a  and  631   c  lie directly under the actuator balls  511   a  and  511   c,  respectively, then at that point the actuator balls  511   a  and  511   c  will rest in their respective detents and will be exerting minimal pressure on the first layer  211 ; the side channels  424   a  and  424   c,  which are positioned directly above the actuator balls  511   a  and  511   c,  respectively, will be open, and fluid will flow from the fluid storage containers  436   a  and  436   c  through their respective open side channels and into the main channel  422 , where the fluids will proceed to the mixing vessel  446 . At the same time, the actuator balls  511   b  and  511   d,  which are not resting in detents, will be pushed upward by the cam  611  to exert deformative pressure on the first layer  211  to pinch their respective side channels  424   b  and  424   d.  With the channels  424   b  and  424   d  pinched, fluid does not flow from the two fluid storage containers  436   b  and  436   d.    
         [0054]    The particular combination of open and closed microvalves described in the previous paragraph, which depends upon the cam  611  being in a particular position so that some actuator balls are in detents and others are not, is called a state, and it is feasible for a single cam to have multiple states, determined by parallel rows of detents on longitudinal lines on the curved surface of the cylinder cam  611 . The invention allows a single cam to control a number of microvalves in combination and to control the mixing of fluids in the microfluidic system. In various applications, each of the fluid storage vessels  436   a - d  contains a different chemical reagent, and the combination of cam-driven microvalves allows for the rapid and controlled mixture of selected reagents according to a state selected by rotating the cam  611 . 
         [0055]    Those of skill in the art will understand that, although the illustrated embodiment in  FIGS. 11 and 12  includes four fluid storage vessels  436   a - d,  an embodiment of the apparatus could include fewer or more fluid storage vessels without altering the basic concept of the apparatus. 
         [0056]    Those of skill in the art will recognize that the cylinder cam described above, in various embodiments, is adapted to be used with multifunction devices, including but not limited to distribution valves, switching valves, peristaltic pumps, and other devices. In other embodiments, two or more actuators work as a differential to produce a complex array of actuation states. 
         [0057]    In the embodiments illustrated in  FIGS. 2-12 , the cam comprises a cylinder with detents on the curved surface of the cylinder and the cylinder&#39;s axis of rotation running approximately parallel to the plane of the elastomeric first layer.  FIG. 13  shows one embodiment of the invention with an alternative style of cam. In this embodiment, the microvalve  1013  includes a cylinder-shaped cam  6013  in which the cylinder&#39;s central axis of rotation is approximately perpendicular to the plane of the first layer  2013 . As is shown in the exploded view of  FIG. 14 , the cylinder-shaped cam  6013  has a flat, circular surface oriented toward the first layer  2013 . This flat, circular surface of the cam  6013  includes a detent  6313 . The microvalve  1013  also includes an actuator ball  5013 , a guide tube  5513 , a cam-driving axle  6513 , and a PCM  7013 . During operation, the PCM  7013  rotates the cam-driving axle  6513  to rotate the cam  6013  about the cam&#39;s central axis of rotation. As the cam  6013  rotates, the actuator ball  5013 , which does not rotate with the cam  6013 , moves into and out of the detent  6313  and therefore moves within the guide tube  5513  away from and towards the first layer  2013 . When the actuator ball  5013  rests in the detent  6313 , the actuator ball  5013  exerts minimal pressure on the first layer  2013 , and thus the channel  4013  within the second layer  3013  remains open, the flow of fluid through the channel  4013  being unobstructed. When the cam  6013  rotates and moves the detent  6313  away from the actuator ball  5013 , then the actuator ball  5013  moves out of the detent  6313 , and the actuator ball  5013 , pushed by the surface of the cam  6013 , moves within the guide tube  5513  toward the first layer  2013 , thereupon exerting deformative pressure on the first layer  2013  and pinching the microvalve  1013 , thereby obstructing the flow of fluid through the channel  4013 . The style of cam  6013  shown in  FIGS. 13 and 14  is designated a “rotary-style” cam to distinguish it from the cylinder cams shown in  FIGS. 2-12 . 
         [0058]      FIG. 15  shows one embodiment of the invention with an alternative style of cam. As is shown in the exploded view of the embodiment in  FIG. 16 , in this embodiment, the microvalve  1015  includes a flat, plate-shaped cam  6015  in which the surface of the plate oriented toward the first layer  2015  includes a detent  6315 . The microvalve  1015  also includes an actuator ball  5015 , a guide tube  5515 , a cam-driving rod  6515 , and a PCM  7015 . During operation, the PCM  7015  moves the cam-driving rod  6515  to laterally move the cam  6015  through a range of positions on a line approximately parallel to the plane of the first layer  2015 . As the cam  6015  moves, the actuator ball  5013 , which does not move with the cam  6015 , moves into and out of the detent  6315  and thereby moves within the guide tube  5515  away from and towards the first layer  2015 . When the actuator ball  5015  rests in the detent  6315 , the actuator ball  5015  exerts minimal pressure on the first layer  2015 , and thus the channel  4015  within the second layer  3015  remains open, the flow of fluid through the channel  4015  being unobstructed. When the cam  6015  moves laterally and thereby moves the detent  6315  away from the actuator ball  5015 , then the actuator ball  5015  moves out of the detent  6315 , and the actuator ball  5015 , pushed by the surface of the cam  6015 , moves within the guide tube  5515  toward the first layer  2015 , thereupon exerting deformative pressure on the first layer  2015  and pinching the microvalve  1015 , thereby obstructing the flow of fluid through the channel  4013 . 
         [0059]    Those of skill in the art will recognize that both the rotary cam and the plate cam described above, in various embodiments, are equipped with multiple detents and adapted to operate with several actuator balls positioned to pinch different channels, as is done with the cylinder cam in  FIG. 8  and  FIG. 11 , among other embodiments. Those of skill in the art will also recognize that, as with the cylinder cam, the rotary cam and the plate cam, in various embodiments, are adapted to be used with multifunction devices, including but not limited to distribution valves, switching valves, peristaltic pumps, and other devices. 
         [0060]    In the illustrated embodiments in  FIGS. 2-16 , the cam features one or more detents adapted to allow an actuator ball to move away from the elastomeric first layer; when an actuator ball is not resting in one of the detents, it is positioned on an undetented portion of the cam surface and is pressing against the first layer, pinching the valve. However, in some embodiments a cam-driven microvalve according to the present invention includes a cam with one or more raised areas or bumps rather than detents. In these embodiments, when the actuator ball is resting on or against the unraised portion of the surface of the cam, the actuator ball does not exert deformative pressure on the first layer. As the cam moves and the bump or raised area moves into position so that the actuator ball now rests on or against the bump or raised area, the actuator ball exerts deformative pressure on the first layer. Additional modifications and embodiments will be readily apparent to those skilled in the art. 
         [0061]    In some embodiments a cam-driven microvalve according to the present invention is included in a peristaltic micropump.  FIG. 17  shows a perspective view of one embodiment of a cam-driven peristaltic micropump. As shown in  FIG. 17  and in the exploded view of the same embodiment in  FIG. 18 , the device  1017  includes an elastomeric first layer  2017  and a second layer  3017  that cooperatively define a channel  4017 , with fluid flowing into and out of the channel  4017  through an inlet  4117  and outlet  4217  in the second layer  3017 . A rotary-style cam  6017 , similar to the rotary-style cam shown in  FIGS. 13 and 14 , supports a plurality of actuator balls  5017   a - d.  (In the illustrated embodiment, four actuator balls are shown; other embodiments of the cam-driven peristaltic micropump have a lesser or greater number of actuator balls, although preferably the cam-driven peristaltic micropump includes a minimum of three actuator balls.) A PCM  7017  is positioned and adapted to control the rotary movement of the rotary-style cam  6017 . 
         [0062]      FIG. 19  shows a top-down view of the embodiment shown in  FIGS. 17 and 18 , with the second layer  3017  removed.  FIGS. 20A and 20B  likewise show a topdown view of the same embodiment as  FIGS. 17-19 , with the first layer and the second layer removed to better show the rotary-style cam  6017 . As shown in these Figures and in the sectional views of  FIGS. 21A and 21B , the cam  6017  moves the actuator balls  5017   a - d  in a pattern to move fluid through the channel  4017  in a chosen direction. For example, in  FIGS. 20A and 21A , the cam  6017  is in a first state wherein three of the four actuator balls,  5017   a - c,  are pinching the channel  4017  at certain points along the course of the channel  4017 . Then, as the cam  6017  rotates into a second state, shown in  FIGS. 20B and 21B , the actuator balls  5017   a - d  are now pinching the channel  4017  at different “pinch points” along the course of the channel. As the cam  6017  continues to rotate, the actuator balls  5017   a - d  are continuously deforming the first layer  2017  at points along the course of the channel  4017 ; fluid caught within the channel  4017  between the rotating pinch points is driven in the direction of rotation as the cam  6017  rotates and the actuator balls  5017   a - d  continue their revolution. 
         [0063]    The speed with which fluid moves through the pump  1017  is controlled by the speed with which the cam  6017  rotates. In alternative embodiments, a set of actuator balls are engaged and disengaged in sequence along the course of a channel to displace and drive fluid in the channel. Additional modifications and embodiments will be readily apparent to those skilled in the art. 
         [0064]    While the present invention has been illustrated by description of several embodiments, and while the illustrative embodiments have been described in detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant&#39;s general inventive concept.