Patent Publication Number: US-11028840-B2

Title: Microelectromechanical systems fabricated with roll to roll processing

Description:
This application claims priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application Ser. No. 62/073,092, filed Oct. 31, 2014, and entitled “Micro Pump Systems”, the entire contents of which is hereby incorporated by reference. 
    
    
     INTRODUCTION 
     This specification relates to microelectromechanical systems. 
     Microelectromechanical systems (MEMS) is the name given to a technology in which electro-mechanical components of micro-meter size are fabricated on substrates of silicon using silicon semiconductor process lines that are commonly used in semiconductor device fabrication, i.e. deposition of material layers that are patterning by photolithography and etching processing, polymers using processes such as injection molding, embossing or stereo-lithography (3D printing) especially for microfluidic applications, and metals that are deposited by electroplating, evaporation, and sputtering processes. Ceramics such as nitrides of silicon, aluminum and titanium as well as silicon carbide and other ceramics materials properties. Microelectromechanical systems typically include a central unit that processes data and several components that interact with surroundings. Examples of microelectromechanical systems include micro-sensors (bio, chemical and mechanical), various types of structures and micro-actuators. 
     SUMMARY 
     Described are roll to roll fabrication techniques for producing microelectromechanical systems (MEMS) such as a micro-pump. Roll to roll processing can be used to manufacture a variety of microelectromechanical systems (MEMS). Disclosed are specific roll to roll fabrication techniques to produce mechanical structures that are releasable mechanical structures and movable, mechanical structures in the specific microelectromechanical systems, which specific parts to move in operation of the microelectromechanical systems. 
     According to an aspect, a method of manufacturing a microelectromechanical system that a fixed body element and a releasable and movable feature in association with the fixed body element includes patterning a first sheet of a flexible plastic material having a metal coating on one surface of the sheet to produce a first metallic region on the one surface, patterning the first sheet to produce the fixed body element from the first sheet of flexible plastic material and the releasable and movable feature from the portion of the first sheet having the first metallic region, with the patterning of the releasable and movable feature leaving the releasable and movable feature tethered to a portion of the fixed body element, and laminating a second sheet of a flexible plastic material to the first sheet to provide a composite laminated structure. 
     The following are some embodiments within the scope of this aspect. 
     In the method the microelectromechanical system is a micro-pump, and the fixed body element is a pump body and the releasable and movable element is a valve element. The patterning of the first sheet includes ablating, and produces the first metallic region and a second metallic region on the first sheet, with the movable, releasable element being a first movable, releasable element and the micro pump comprising a second movable, releasable element patterned from the portion of the first sheet having the second metallic region, with the first and second movable, releasable elements being valve elements at inlets and outlets of the pump body. The movable, releasable elements are a T-shaped member of a T valve and an Omega-shaped member of an Omega valve. The method further includes depositing on the second sheet of a conductive layer on a first surface of the second sheet. The depositing of the conductive layer occurs prior to lamination of the second sheet. 
     The microelectromechanical system is fabricated on a roll to roll processing line, and the method further includes removing the first sheet of the flexible plastic material having the metal coating from a first roll; and removing the second sheet of the flexible plastic material having a metal coating on one surface from a second roll; and wherein ablating occurs at a first station, patterning occurs at a second station, and lamination occurs at a third station. The method further includes depositing on the second sheet of a conductive layer on a first surface of the second sheet and patterning the conductive layer on the second sheet to provide isolated regions of the conductive layer that provide electrodes on the second sheet. The method further includes dicing the composite laminated structure into individual dies comprising the fixed body element and the releasable and movable feature, stacking the individual dies to produce a stacked structure, and laminating the stacked structure to produce a component of the microelectromechanical system. The microelectromechanical system is a micro-pump, and the fixed body element is a pump body and the releasable and movable element is a valve element; with patterning of the first sheet comprises ablating, for producing the first metallic region and a second metallic region on the first sheet, with the movable, releasable element being a first movable, releasable element and the micro pump comprising a second movable, releasable element patterned from the portion of the first sheet having the second metallic region, with the first and second movable, releasable elements being valve elements at inlets and outlets of the pump body. 
     According to an aspect, a method of manufacturing a microelectromechanical system in a roll to roll processing line includes unrolling from a first roll a first web of a flexible material having a metal coating on one surface of the sheet, unrolling from a second roll a second web of a flexible material, producing at a first patterning station a body element and a movable element from the second sheet of material as the sheet traverses through the first patterning station, unrolling from a third roll a third web of a flexible material having a metallic layer on the third sheet and laminating at a laminating station the third web to the second web. 
     The following are some embodiments within the scope of this aspect. 
     The microelectromechanical system is a micro-pump and the movable, releasable element is a valve element. The micro-pump and two movable, releasable elements that are valve elements at inlets and outlets of the body that is a pump body. The method further includes applying a sacrificial filling material to the body element and movable element and after laminating, removing the sacrificial filling material with a suitable solvent. 
     One or more aspects may include one or more of the following advantages. 
     With these techniques, microelectromechanical systems such as micro-sensors, micro actuators, micro pumps are fabricated with releasable and movable (freely movable and well as bendable) features that can be made by techniques such as roll to roll processing. Such microelectromechanical systems having such features can be fabricated in a very inexpensive manner using roll to roll (R2R) processing. 
     The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention are apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIGS. 1A and 1B  are functional block diagrams of a microelectromechanical system as a micro pump operating in two opposite phases of a pumping cycle. 
         FIG. 2A  is an assembled view of a stack of assembled module layers. 
         FIG. 2B  is an exploded view of module layers. 
         FIG. 2C  is an assembled view of the module layer of  FIG. 2B . 
         FIG. 2D  is an exploded view of an intermediate module layer. 
         FIGS. 3 and 4  are plots of voltage waveforms for application to electrodes of a micro pump. 
         FIG. 5  is a block diagram of an exemplary drive circuit. 
         FIG. 6  is a block diagram of micro pumps arranged in an exemplary grid configuration. 
         FIG. 7  is a perspective view of micro pumps integrated in a die frame. 
         FIGS. 8A and 8B  are respective top side view and bottom side view of an exemplary cooling device in a cooling arrangement. 
         FIGS. 9A-9C  are respective perspective, front, and solid views of an airway pressure breathing device. 
         FIG. 10  is a block diagram of a CPAP device. 
         FIGS. 10A-10F  are views of an exhalation valve. 
         FIGS. 11A-11D  show details of exemplary sliding valves. 
         FIG. 12  is a conceptual diagram of a roll to roll processing configuration. 
         FIG. 12A  is a conceptual view of some of the exemplary roll to roll processing stations for the structure of  FIG. 2B . 
         FIGS. 13A-13D  are views of a roll to roll implementation for constructing a device with releasable and movable features. 
         FIG. 13A-1  is a blown up view of a portion of  FIG. 13A . 
         FIG. 14  is a view of a mask. 
     
    
    
     DETAILED DESCRIPTION 
     Overview 
     Microelectromechanical systems such as micro-sensors, micro actuators of which a micro pump as discussed below are fabricated by roll to roll processing. 
     Microelectromechanical systems can be lab-on-a-chip systems, can be used in fuel cells, high flux electronic cooling systems, and biochemistry systems. The microelectromechanical systems such as micro pumps can transport fluids, e.g., gas or liquids, in small, accurately measured quantities. The micro pumps can be used in various applications. As being fabricated with roll to roll techniques these devices can be made very inexpensively. 
     Micro Pump Systems 
     Micro Pumps 
     Microelectromechanical systems fabricated by roll to roll processing will now be described in conjunction with the micro-pump example. 
       FIG. 1  shows a micro pump  100  that includes a single compartmentalized pump chamber  104 . The pump body  102  includes two walls  110 ,  112  along the pumping direction  114 , and two fixed end walls  106 ,  108  opposite to each other along a direction perpendicular to the pumping direction  114 . The walls  106 ,  108 ,  110  and  112  define the single chamber  104  that is compartmentalized by membranes. That is, between the two end walls  106 ,  108 , membranes  116 ,  118 ,  120 ,  122 ,  124 ,  126  extend from the wall  110  to the wall  112 , separating the pump chamber  104  into seven compartments  130 ,  132 ,  134 ,  136 ,  138 ,  140 ,  142 . In this implementation, each compartment includes an inlet and an outlet defined in the walls  110 ,  112 , respectively. For example, the compartment  130  includes an inlet  150  in the wall  110  and an outlet  152  in the wall  112 . Other inlets and outlets are not labeled. 
     The compartments  130 - 142  are fluidically sealed from each other. In some implementations, different compartments can have the same inlet and/or the same outlet (not shown in the figure) and these different compartments may fluidically communicate with each other. Two compartments  130 ,  142  at the opposite ends of the pump chamber  104  have walls provided by a fixed wall of the pump body  102  and a membrane. All other intermediate compartments between the compartments  130 ,  142  have walls formed of two membranes. In some embodiments at least one intermediate compartment has compartment walls formed of two membranes. Although six membranes are shown in the figures, the pump chamber can be extended with additional intermediate compartments. An electrode (not explicitly shown in  FIGS. 1A and 1B , see,  FIGS. 2A and 2C ) is attached to each of the membranes  116 - 126  and optionally to the end walls caps  106 ,  108 . 
     The electrodes are connected to a drive circuit (see  FIGS. 3-5 ), that delivers voltages to the electrodes to activate the membranes through electrostatic attraction/replusion. Without activation, the membranes rest at nominal positions identified by the dotted lines in the figures. Each membrane at rest can be substantially parallel to the end walls  106 ,  108  and the compartments  132 - 140  can have the same nominal volume V i . For example, the distance between two adjacent membranes in their nominal positions is about 50 microns, and the nominal volume V i  can range from nanoliters to microliters to milliliters, e.g., 0.1 microliters. 
     In some implementations, the compartments  130 ,  142  each has a nominal volume V e  that is half the nominal volume of the intermediate compartments  132 - 140 . For example, the distance between the membrane  116  in its nominal position and the end wall  106  or between the membrane  126  in its nominal position and the end wall  108  is about 25 microns. The nominal volume V e  can range from nanoliters to microliters to milliliters, e.g., 0.05 microliters. The compartments  130 - 142  can also have different sizes. The sizes are chosen based on, e.g., specific process requirements of a roll to roll manufacturing line, as well as, power consumption, and application considerations. 
     For example, the compartments  130 ,  142  having a width of 25 microns can allow a start-up function with a reduced peak drive voltage. Drive voltages are discussed further below. As an example, the micro pump can have an internal volume having a length of about 1.5 mm, a width of about 1.5 mm, a total height (the cumulative height of different compartments) of 0.05 mm, and a total volume of about 0.1125 mm 3 . 
     Compared to a conventional pump used for similar purposes, the micro pump uses less material that is subject to less stress, and is driven using less power. The micro pump has a size in the micron to millimeter scale, and can provide wide ranges of flow rates and pressure. Approximately, a flow rate provided by a micro pump can be calculated as:
 
The total volume of the micro pump×drive frequency.
 
     Generally, the flow rate can be in the scale of microliters to microliters. Generally, the pressure is affected by how much energy, e.g., the drive voltage, is put into the micro pump. In some implementations, the higher the voltage, the larger the voltage, and the upper limit on voltage is defined by break down limits of the micro pump and the lower limit on the voltage is defined by the membrane&#39;s ability to actuate. The pressure across a micro pump can be in the range of about micro psi to tenths of a psi. A selected range of flow rate and pressure can be accomplished by selection of pump materials, pump design, and pump manufacturing techniques. The described micro pump is a displacement type pump in the reciprocating category. Pumping occurs in two alternating operations including fluid, e.g., gas or a liquid, charging and fluid discharging through the actuation of a pump chamber of the micro pump. In the charging operation, the pump chamber is opened to a lower pressure source and the fluid fills into the chamber. In the discharging operation, the fluid inside the pump chamber is compressed out of the pump chamber to a higher pressure sink. 
       FIGS. 1A and 1B  show two operational states of the same pump, a compartment is compressed when adjacent membranes move towards each other and reduce the volume of the compartment to discharge gas from the compartment. Simultaneous to the compression of that compartment, adjacent compartments are charged when its two membranes move away from each other to expand the chamber volume. When actuated, each membrane of the pump chamber can move in two opposite directions about a central, nominal location at which the membrane rests when it is not actuated. 
     In operation, the membrane of the conventional pump chamber forms a single pump chamber compartment, which is used in pumping. Gas is charged and discharged once during the charging and discharging operations of a pumping cycle, respectively. The gas outflows only during half of the cycle, and the gas inflows during the other half of the cycle. 
     In the instant micro pump, each compartment is used in pumping. For example, two membranes between two fixed end walls form three compartments for pumping. The micro pump can have a higher efficiency and can consume less energy than a conventional pump performing the same amount pumping, e.g., because the individual membranes travel less distance and therefore are driven less. The efficiency and energy saving can further increase when the number of membranes and compartments between the two fixed end walls increases. 
     Generally, to perform pumping, each compartment includes a gas inlet and a gas outlet. The inlet and the outlet can include a valve, e.g., a passive valve that opens or closes in response to pressure applied to the valve. In some implementations, the valves are flap valves and are driven by a differential pressure across the valves created by flow of gas in or out of the pump compartment. Because no active driving is required, the flap valves can reduce the complication of pump operation. Alternatively, it is also possible to build a micro pump in a valve-less fashion using nozzles and diffusers. 
     Generally, the membranes are driven to move by electrostatic force. An electrode can be attached to each of the fixed end walls and the membranes. During the charging operation of a compartment, the two adjacent electrodes of the compartment have the same positive or negative voltages, causing the two electrodes and therefore, the two membranes to repel each other. During the discharging operation of a compartment, two adjacent electrodes of the compartment have the opposite positive or negative voltages, causing the two electrodes and therefore, the two membranes to attract to each other. 
     The two electrodes of a compartment form a parallel plate electrostatic actuator. The electrodes generally have small sizes and low static power consumption. A high voltage can be applied to each electrode to actuate the compartment. But the actuation can be performed at a low current. 
     As described previously, each membrane of the micro pump moves in two opposite directions relative to its central, nominal position. Accordingly, compared to a compartment in a conventional pump, to expand or reduce a compartment by the same amount of volume, the membrane of this specification travels a distance less than, e.g., half of, the membrane in the conventional pump. As a result, the membrane experiences less flexing and less stress, leading to longer life and allowing for greater choice of materials. In addition, because the travel distance of the membrane is relatively small, the starting drive voltage for the electrode on the membrane can be relatively low. Accordingly, less power is consumed. For a compartment having two membranes, since both membranes are moving, the time it takes to reach the pull-in voltage can be shorter. 
     A drive circuit for applying voltages to the electrodes takes a low DC voltage supply and converts it to an AC waveform. The frequency and shape of the waveform can be controlled by a voltage controlled oscillator. The drive voltage can be stepped up by a multiplier circuit to the required level. 
     Microelectromechanical systems such as micro pumps having the above described features are fabricated using roll to roll (R2R) processing. Roll-to-roll processing is becoming employed in manufacture of electronic devices using a roll of flexible plastic or metal foil as a base or substrate layer. Roll to roll processing has been used in other fields for applying coatings and printing on to a flexible material delivered from a roll and thereafter re-reeling the flexible material after processing onto an output roll. After the material has been taken up on the output roll or take-up roll the material with coating, laminates or print materials are diced or cut into finished sizes. 
     Below are some example criteria for choosing the materials of the different parts of the micro pump. 
     Pump body and valves—The material used for the body of a pump may be defined by the requirements of the integrated flap valves, if the flap valves are made of the same material as the body. In some implementations, the material needs to be strong or stiff enough to hold its shape to provide the pump chamber volume, yet elastic enough to allow the flap valves to move as desired. In addition, the choice can be influenced by the geometric design of the flap valves. In some implementations, the material is etch-able or photo-sensitive so that its features can be defined and machined/developed. Sometimes it is also desirable that the material interact well, e.g., adheres with the other materials in the micro pump. Furthermore, the material is electrically non-conductive. Examples of suitable materials include SU8 (negative epoxy resist), and PMMA (Polymethyl methacrylate) resist. 
     Membrane—The material for this part forms a tympanic structure (a thin tense membrane covering the pump chamber) that is used to charge and discharge the pump chamber. As such, the material is required to bend or stretch back and forth over a desired distance and has elastic characteristics. The membrane material is impermeable to fluids, including gas and liquids, is electrically non-conductive, and possesses a high breakdown voltage. Examples of suitable materials include silicon nitride and Teflon. 
     Electrodes—This structures are very thin and comprised of material that is electrically conductive. Because the electrodes do not conduct much current, the material can have a high electrical resistance, although the high resistance feature is not necessarily desirable. The electrodes are subject to bending and stretching with the membranes, and therefore, it is desirable that the material is supple to handle the bending and stretching without fatigue and failure. In addition, the electrode material and the membrane material will need to adhere well to each other, e.g., will not delaminate from each other, under the conditions of operation. Examples of suitable materials include gold, and platinum. 
     Electrical interconnects—The drive voltage is conducted to the electrode on each membrane of each compartment. Electrically conducting paths to these electrodes can be built using conductive materials, e.g., gold, and platinum. 
     In  FIGS. 2A-2D , a modularized micro pump is shown. 
     Referring to  FIG. 2A  a modularized micro pump  200  is comprised of module layers  201  ( FIGS. 2B and 2C ) to form end compartments  200   a ,  200   b  of the pump  200 . The modularized micro pump  200  is also comprised of many module layers  250  ( FIG. 2D ) to form intermediate compartments  200   c  of the pump  200 . 
     The valves in the micro pump  200  can be replaced by single valves connected to the input and the output or the individual valves in each layer can be staggered. Specific details on modularized micro pump fabrication with roll to roll processing are discussed below. 
     Referring now to  FIG. 2B , the module layers  201  each include a pump end cap  202  forming a fixed pump wall (similar to walls  106 ,  108   FIGS. 1A, 1B ). An electrode  208  is attached to the pump end cap  202  for activating a compartment  209 . 
     A single module layer  201  forms a portion of a pump body  204  between the pump end cap  202  with the electrode  208 , and a membrane  206  along with an electrode  210  that is attached to the membrane  206  on the opposite side of the pump body  204  (similar as the membrane  116 ,  126  in  FIGS. 1A, 1B ). The electrode  210  includes a lead  212  to be connected to a drive circuit external to the module layer  200 . 
     The membrane  206 , the pump end cap  202 , and the pump body  204  can have the same dimensions, and the electrodes  208 ,  210  can have smaller dimensions than the membrane  206  or the other elements. In some implementations, the membrane  206  has a dimension of about microns by microns to about millimeters by millimeters, and a thickness of about 5 microns. The pump body  204  has an outer dimension of about microns by microns to about millimeters by millimeters, a thickness of about 50 microns, and an inner dimension of about microns by microns to about millimeters by millimeters. The thickness of the pump body defines the nominal size of the compartment  209  (similar to compartments  130 ,  142   FIG. 1A ). The electrodes  210 ,  202  have dimensions that substantially correspond to inner dimensions of the pump body  204 . In some implementations, the electrodes have a surface area of about 2.25 mm 2  and a thickness of about 0.5 microns. An assembled module layer  201  is shown in  FIG. 2C . 
     Referring now also to  FIG. 2C , the pump body  204  includes two passive valves  214 ,  216 , forming an inlet and an outlet, respectively. The inlet valve  214  includes a stopper  218  and a flap  220 . The stopper is connected to the pump body  204  and is located external to the compartment  130 ,  140  formed by the pump body. The flap  220  has one end  222  attached to the pump body  204  and another end  224  movable relative to the stopper  218  and the pump body  204 . In particular, the end  224  of the flap can bend towards the interior of the compartment  130 ,  140  when a pressure differential is established such that the pressure external to the module layer is larger than the pressure inside the module layer. For example, such a pressure differential is established during a charging operation in which a fluid flows from outside the module layer into the compartment  209 . When the internal pressure is higher than the external pressure, e.g., during a discharge operation in which a fluid flows from the compartment  209  away to the outside of the module layer, the flap  224  bends towards the stopper and is stopped by the stopper  218 . Accordingly, during the discharge operation, the fluid in the compartment  209  does not flow out from the inlet valve  214 . 
     The outlet valve  216  also includes a stopper  230  and a flap  232  similar to the stopper  218  and the flap  220 , respectively. However, the stopper  230  is located in front of the flap  232  along a direction in which the fluid flows into or out of the compartment  209 . When the internal pressure is higher than the external pressure, the flap bends away from the stopper to open the valve and when the internal pressure is lower than the external pressure, the flap bends towards from the stopper to close the valve. Effectively, during the charging operation, the outlet valve  216  is closed so that the fluid does not flow out of the valve  216 , and during the discharging operation, the outlet valve  216  is open and the fluid flows out from the valve  216 . 
     Referring to  FIG. 2D , intermediate compartments (similar to compartments  132 - 140   FIGS. 1A-B ) can each be formed using a module layer  250 . The module layer  250  includes a pump body  252 , an electrode  256 , and a membrane  254  formed between the electrode  256  and the pump body  252 . The pump body  252  can have similar or the same features as the pump body  204 , the electrode  256  can have similar or the same features as the electrode  208 , and the membrane  254  can have similar or the same features as the membrane  206 . The module layer  250  also includes flap valves (not referenced but shown in the figure.) 
     As described previously, the valves of each pump body can be formed integrally with the pump body. Although the electrodes are shown as a pre-prepared sheet to be attached to the other elements, the electrodes can be formed directly onto those elements, e.g., by printing. The different elements of the module layers  200 ,  250  can be bonded to each other using an adhesive. In some implementations, a solvent can be used to partially melt the different elements and adhere them together. 
     Referring back to  FIG. 2A , thus multiple, e.g., two, three, or any desired number of, module layers  250  of  FIG. 2D  are stacked on top of each other to form multiple intermediate compartments in a pump chamber. In the stack  200 , each membrane is separated by a pump body and each pump body is separated by a membrane. To form a complete pump, a module layer  201  of  FIG. 2B  is placed on each of the top and bottom ends of the stack  200  so that the pump end caps of the module layer  201  form two fixed end walls of the pump chamber. 
     Referring again to  FIGS. 1A and 1B , during each pumping cycle, the compartments are activated such that each compartment charges during half of the cycle and discharges during the other half of the cycle. Adjacent compartments operate in 180 degree phase difference, i.e., when the compartment  130  is charging, its adjacent compartment  132  is discharging, and vice versa. As a result, every other compartment operates in phase. In  FIGS. 1A and 1B , the compartments are labeled by odd-numbered (“O”) compartments and even-numbered (“E”) compartments, the O compartments are in phase with each other, the E compartments are in phase with each other, and the O compartments are out of phase relative to the E compartments. 
     To operate compartments of the pump in their discharging state, voltages of opposite signs are applied to the electrodes on opposing walls of these compartments. For example, as shown in  FIG. 1A , the voltage of the electrode on the fixed wall  106  is negative while the voltage of the electrode on the membrane  116  is positive, or the voltage of the electrode on the membrane  118  is positive while the voltage of the electrode on the membrane  120  is negative, etc. Simultaneously, the other compartments of the pump are operated in their charging state. Voltages of the same signs are applied to the electrodes on opposing walls of these other compartments. The voltages of opposite signs cause the two opposing walls of the compartments to attract each other and the voltages of the same signs cause the two opposing walls of the compartments to repel each other. The fixed walls  106 ,  108  do not move. However, the membranes  116 - 126  move towards a direction of the attraction force or a direction of the repelling force. As a result, in half of a pumping cycle, the compartments  130 ,  134 ,  138 ,  142  discharge and the other compartments simultaneously charge ( FIG. 1A ), and in the other half of the pumping cycle, the compartments  132 ,  136 ,  140  discharge and the other compartments simultaneously charge ( FIG. 1B ). 
     In some implementations, the material of the membranes and the voltages to be applied to the membranes and the end walls  106 ,  108  are chosen such that when activated, each membrane expands substantially half the distance d between the nominal positions of adjacent membranes. In the end compartments  130 ,  142  where the distance between the nominal position of the membrane and the fixed wall is d/2, the activated membrane reduces the volume of the compartment to close to zero (in a discharging operation) and expands the volume of the compartment to close to 2*V e . For the intermediate compartments, by moving each membrane by d/2, a volume of a compartment is expanded to close to 2*V i  in a charging operation and reduced to close to zero in a discharging operation. The micro pump  100  can operate at a high efficiency. 
     The period of the pumping cycle can be determined based on the frequency of the drive voltage signals. In some implementations, the frequency of the drive voltage signal is about Hz to about KHz, e.g., about 2 KHz. A flow rate or pressure generated by the pumping of the micro pump  100  can be affected by the volume of each compartment, the amount of displacement the membranes make upon activation, and the pumping cycle period. Various flow rates, including high flow rates, e.g., in the order of ml/s, and pressure, including high pressure, e.g., in the order of tenths of one psi, can be achieved by selecting the different parameters, e.g., the magnitude of the drive voltage. As an example, a micro pump can include a total of 15 module layers, including two layers  200  of  FIG. 2B  and 13 layers  250  of  FIG. 2C . This example micro pump can be drive at a frequency of about 843 Hz and consumes power of about 0.62 mW, and provides a flow rate of about 1.56 ml/s at about 0.0652 psi. 
     In some implementations, four types of electrical signals are used to drive the membranes. The four types are:
         V−: a DC reference for all the voltages; may be used to drive some membranes directly;   V+: a DC high voltage used to drive some membranes directly and switched for others;   V1: a periodic AC waveform used to drive some membranes to control operation. It includes a 50% duty cycle and swings between V− and V+ in one full pumping cycle.   V2: identical to V1 except it is 180 degrees out of phase.       

     Furthermore, based on the phenomenon of pull-in and drop-out voltages, the drive voltage can be reduced to a lower voltage once the highest magnitude of V1 or V2 has been reached. In particular:
         V1.5: the pull-in voltage value.   V2.5: the drop-out voltage value.       

     Referring now to  FIG. 3 , six example sets of waveforms  301 - 306  for application onto six electrodes on the fixed wall  106  and the membranes  116 - 124 , respectively are shown. The waveforms applied to other additional membranes and fixed wall in the micro pump  100  or other micro pumps can be derived by the pattern shown in  FIG. 3 . During pumping cycles, V− of the first set of waveform  301  is constantly applied to the electrode on the fixed wall  106 . The second set of waveform  302  for applying to the membrane  116  is in the form of V1. The third set of waveform  303  is V+ and is constantly applied to the membrane  118 . The fourth set of waveform  304  is V2 for applying to the membrane  120 . The fifth set of waveform  305  and sixth set of waveform  306  are a repeat of the first and second waveforms  301 ,  302 . If additional waveforms are needed for other membranes, e.g., membranes  124  and  126  ( FIG. 1A ) the repetition continues with the third and fourth waveforms, and etc. 
     In some implementations, the magnitudes of V1, V2, V−, and V+ are the same. In other implementations, magnitudes of at least some of these voltages are different. Although a particular pattern of waveforms are shown, the electrodes of the pump  100  can also be activated by other patterns of waveforms. 
     Referring now to  FIG. 4 , six sets of waveforms  321 - 326  corresponding to the six sets of waveforms  301 - 306  of  FIG. 3 , respectively are shown. The difference between the sets shown in  FIG. 4  and the sets shown in  FIG. 3  is that the AC voltage waveforms V1 and V2 of  FIG. 3  are reshaped into V1.5 and V2.5, respectively to take the advantage of pull-in and drop-out phenomena. 
     In this example, in the waveform sets  322 ,  324 ,  326 , the positive going voltage is stepped down (shown by arrows ↓) to a lower voltage once the pull-in point has been reached. This lower voltage is still greater than the drop-out voltage so that the membranes remain in their driven state. The next voltage transition defines the beginning of the opposite operation, during which a similar voltage level shift is applied. The negative going voltage is stepped up (shown by arrows ↑) to a voltage having a smaller magnitude. The power consumption of the pump  100  can be reduced by reducing the magnitude of the drive voltages during their hold time. 
     Drive Circuitry 
     Referring now to  FIG. 5 , an example of drive circuitry  500  for applying voltages, such as those shown in  FIG. 3  or  FIG. 4  is shown. The drive circuitry  500  receives a supply voltage  502 , a capacitance voltage current  504  signal, and pump control  516 , and outputs drive voltages  506  to electrodes of a micro pump, such as the micro pump of  FIGS. 1A and 1B . In some implementations, the supply voltage  502  is provided from a system in which the micro pump  100  is used. The supply voltage can also be provided by an isolation circuit (not shown). 
     The drive circuitry  500  includes a high voltage multiplier circuit  508 , a voltage controlled oscillator (“VCO”)  510 , a waveform generator circuit  512 , and a feedback and control circuit  514 . The high voltage multiplier circuit  508  multiplies the supply voltage  502  up to a desired high voltage value, e.g., about 100V to 700V, nominally, 500 V. Other voltages depending on material characteristics, such as dielectric constants, thicknesses, mechanical modulus characteristics, electrode spacing, etc. can be used. In some implementations, the high voltage multiplier circuit  508  includes a voltage step-up circuit (not shown). The voltage controlled oscillator  510  produces a drive frequency for the micro pumps. The oscillator  510  is voltage controlled and the frequency can be changed by an external pump control signal  516  so that the pump  100  pushes more or less fluid based on flow rate requirements. The waveform generator circuit  512  generates the drive voltages for the electrodes. As described previously, some of the drive voltages are AC voltages with a specific phase relationship to each other. The waveform generator circuit  512  controls these phases as well as the shape of the waveforms. The feedback and control circuit  514  receives signals that provide measures of capacitance, voltage and or current in the micro pump and the circuit  514  can produce a feedback signal to provide additional control of the waveform generator  512  of the circuit  500  to help adjust the drive voltages for desired performance. 
     Integration of the Systems in Devices 
     The micro pump systems described above can be integrated in different products or devices to perform different functions. For example, the micro pump systems can replace a fan or a blower in a device, e.g., a computer or a refrigerator, as air movers to move air. Compared to the conventional fans or blowers, the micro pumps may be able to perform better at a lower cost with a higher reliability. In some implementations, these air movers are directly built into a host at a fundamental level in a massively parallel configuration. 
     In some implementations, the micro pump systems receive power from a host product into which the systems are integrated. The power can be received in the form of a single, relatively low voltage, e.g., as low as 5V or lower, to a drive circuitry of the micro pump systems, e.g., the drive circuitry  500  of  FIG. 5 . 
     System Configuration 
     The module layer stack of  FIGS. 1A, 1B, and 2D  can be viewed as module layers connected in parallel. The volume of each individual module layer, V i  or V e , is small. In some implementations, even the total volume of all layers in the stack is relatively small. In some implementations, multiple stacks or micro pumps can be connected in parallel to increase the total volume flow rate. 
     Similarly, the pressure capability of an individual micro pump is relatively low. Even though there are multiple module layers in a stack, the layers do not increase the total pressure of the stack because they are connected in parallel. However, the pressure of the stack can be increased when multiple stacks or micro pumps are connected in series. In some implementations, the pumps connected in series are driven at different speeds to compensate for different mass flow rates. For example, built-in plenums or plumbing in a tree type configuration can also be used to compensate for different mass flow rates. 
     Referring now to  FIG. 6 , rows  610 - 616  and columns  610 ′- 616 ′ and column  617 ′ of module layer stacks (which can also be called micro pump stacks)  610   a - 610   e ,  612   a - 612   e ,  614   a - 614   e , and  616   a - 616   e  are shown connected in a grid configuration  600 . The module layer stacks in each row  610 ,  612 ,  614 ,  616  are connected in series. The rows  610 - 616  of module layer stacks  610   a - 610   e ,  612   a - 612   e ,  614   a - 614   e , and  616   a - 616   e  are connected in parallel via a common input  620  and a common output  622 . 
     Effectively, the serially connected stacks in each row can provide a total pressure substantially equal the sum of the individual stack pressures. In the example shown in the figure, if each stack has a pressure of 0.1 psi and each row includes five stacks, then a total pressure of 0.5 psi is effected by each row, and which is also the total pressure of the grid  600 . The grid  600  has a total flow rate that is four times the flow rate of each row of stacks. 
     In the example shown in the figure, each row of stack has a flow rate of 1 volume flow (vF). The grid includes four parallel-connected rows, leading to a total flow rate of 4 vF. To achieve a desired pressure and a desired flow rate, a grid similar to the grid  600  can be constructed by choosing the number of stacks to be serially connected and the number of rows to be connected in parallel. 
     Alternatively, another series configuration has a common plenum disposed between each stage of a grouping of parallel pumps. This configuration would tend to equalize discharge pressures and thus input pressure at the next stage. In some implementations, the stacks are relatively small and many of them can be fabricated in a small area. The plumbing and wiring of the grid can be done at the time of fabrication of the individual stacks and can be done in a cost effective manner. 
     Example Applications 
     As described above, air can be used for an electrochemical reaction and cooling, e.g., in fuel cells. Generally, the amount of air used for cooling is many times more than for the reaction. 
     Referring to  FIG. 7 , a fuel cell with an integrated micro pump system  700  with fluid inputs  700   a  and outputs  700   b  is shown. The micro pump system  600  (or  100  or  200 ) having features described above are integrated directly into a die frame  702  that contains fuel cells  704 . When multiple dies frames are used, generally, there is a minimum spacing among the dies and some of this space can be used to house the micro pump systems  600  with no additional volumetric overhead to the dies. An exemplary fuel cell is disclosed in U.S. application Ser. No. 10/985,736, filed Nov. 9, 2004, now U.S. Pat. No. 7,029,779, and entitled “Fuel cell and power chip technology,” the contents of which are incorporated herein by reference in their entirety. 
     Integrating the air pump systems can effectively divided the air moving function into many, e.g., thousands of parts, minimizing the need for blowers or fans to move the air. The micro pumps can be mass manufactural at a low cost, have small sizes and light weight, be reasonably powerful and consumes low power, allowing for the massive distribution of air movement. The micro pump systems  600  can be used any time air (or liquid) needs to be moved in a tight space. 
     Another such application is the cooling of electronic components like the CPU. 
     Referring now to  FIGS. 8A and 8B , the micro pump ( 100 ,  200 ,  600 ) is used to cool circuits/devices, (e.g., central processor units, etc.) that run at very high temperatures, as well as, e.g., solar cells and LED lighting. 
     As an example,  FIGS. 8A and 8B  show the top side view and bottom side view of a CPU cooler  800 . Instead of a large heat sink and fan arrangement, one or more layers of micro pumps  802  point directly at a cooling plate  804 , for an impingement effect, that is affixed to the CPU. In some implementations, the CPU cooler  800  can remove  150  watts of heat. The cooler has a low profile and can be used in computer designs that have little available space. 
     The micro pump systems can be used to pump a liquid through a cooling plate fastened to the CPU to remove and transfer heat, by the liquid, to a distant location. For example, the hot liquid carrying the heat can be pumped through a radiator and additional micro pumps can be used to blow air to cool the radiator. 
     The micro pump systems can also blow air across a heat sink used in a traditional approach; or can be built into the heat sink. As described previously, the micro pump systems can be configured to provide an increased pressure to push air further. The micro pump systems can also be distributed throughout a host device without needing air ducts. 
     Referring now to  FIGS. 9A and 9B , an autonomous device for treating breathing disorders  900  (device) is shown. The device  900  is a CPAP type (continuous positive airway pressure) breathing device. However, the device  900 , unlike CPAP machines, is an autonomous device that is local to the nose and which provides a required amount of air flow at a required pressure to treat various breathing disorders such as obstructive sleep apnea (“OSA”). 
     The CPAP breathing device  900  is shown in the form of a nose ring. Other arrangements are possible (see  FIG. 9D ). The device  900  has passages  902  for air inlets and micro pumps  600  ( FIG. 6 ) disposed in the body  904  of the device  900 , as shown. The device may also contain valves (See  FIGS. 10 AND 10A-10F ) to provide for exhalation. The ends  904   a ,  904   b  of the device  900 , which fit into the nose of a user, provide airflow via passages  905   a ,  905   b , and sealing and are connected via a ring portion  903  within which can be disposed a power source, e.g., battery (not shown). 
     As the micro pump systems are small and can move a significant amount of air, the micro pump system is built into the device  900 , e.g., to provide relief to many people who have sleep apnea or obstructive breathing disorder (OBD). The device  900  can be a self-contained device that has a small size (e.g., fitting under the nose) and a light weight (e.g., as light as a few grams), and can be operated using batteries. 
     In some implementations, the device  900  can include exhalation valves (discussed below) whereas in other implementations the exhalation valves may be omitted. 
     In some implementations, the device  900  can be rechargeable, e.g., the batteries can be recharged. In others the device can be disposable. A user can wear the device at night and throw it away each day. Alternative arrangements are possible such as the use of air-metal batteries in the devices. The air-metal batteries, (e.g., air-zinc) are activated and last for a period of time, and which thereafter are disposed of. 
     Device  900  is configured to fit into a user&#39;s nose and supplies pressurized air flow from the micro pump  600  (or  100 ,  200 ) built into the ring. The device  900  thus does not require hoses or wires to another device (e.g., a machine) and the device uses a self-contained power source, e.g., a battery that is configured to operate for about a full-night&#39;s sleep, e.g., about eight hours or so. The device  900  does not need straps. The device can be configured to stop blowing air into a user&#39;s nose when a user is exhaling or when a user is in a pause state just prior to inhaling. The device  900  has an exhalation valve that eliminates exhalation resistance (fighting against oncoming air or cutting off the end of exhalation prematurely). 
     The device  900  can sense pressure to turn on and off the micro air pumps. The device  900  senses pressure on every breath and at different points in the breathing cycle to configure operation of the micro air pumps to close the exhalation valve at the “end” of the exhalation cycle. This device responds to the user on a breath by breath basis. 
     The device  900  is small, light-weight and fits under a use&#39;s nose, making a seal in the user&#39;s nose to hold the device in place. The device can provide proper pressure for apnea treatment during a pause period and proper hypopnea pressure range during an inhalation period. The device  900  can be disposable, thus would not require cleaning, can be low cost. Moreover, due to its relative comfort compared to existing CPAP machines, the device  900  promotes compliance as the device is comfortable, require no straps, masks or tethers. 
     Referring now to  FIG. 9C , a conceptual view of an alternative configuration for a CPAP device  960  is shown. In this configuration, the CPAP device  960  includes a body  962  that houses a micro pumps  600  here having 57 component-pump elements denoted as  966 , and an exhalation valve (see  FIGS. 10A-10F ). The CPAP device  960  has cushioned plugs  964   a ,  964   b  with air passages through the plugs that provide a nasal interface. The cushioned plugs are made of a generally rubbery material that make a tight fit when inserted into a user&#39;s nostrils. The CPAP device  960  has one or as shown two outlets  968   a ,  968   b  for exhilaration of air. 
     Referring now to  FIG. 10 , a schematic, e.g., of the configurations shown in  FIGS. 9A-9C , an exhalation valve  980  coupled to a micro pump  600  within the CPAP device  900  or  960  (pumps  966 ). The exhalation valve  980  is coupled between the micro pumps  600  ( 100  or  200  as well) and inlets  964   a ,  964   b  and outlets  968   a ,  968   b  of the device  900 , as shown. The exhalation valve  980  is of a butterfly configuration and uses air flow from the micro pumps to close the valves  980  at the end of an exhalation/beginning of pause in breathing and at the beginning of exhalation, the exhalation valve  980  opens even as the micro pumps blows air on the exhalation valves  980 . 
     The device  900  is configured to select how much of the micro pumps&#39;  600  air flow is needed to push the valve  980  shut. Pressure from the micro pumps  600  will hold the exhalation valve  980  shut prior to exhilaration. All of the exhalation air flow from the user is applied to the exhalation valve  980  to open the exhalation valves  980 . The shape of valves&#39; flaps may be optimized to assist the exhalation valve  980  to stay open during exhalation. In addition, weak magnetics may also be used to keep exhalation valve  980  open or closed depending on details of a design. The exhalation air from a user would generally be sufficient to overcome a minimum amount of air flow from the micro pump to keep the exhalation valves  980  closed. 
     Referring now to  FIGS. 10A-10F , various views of a conceptual exhalation valve  980  are shown.  FIGS. 10A-10F  show a butterfly valve configuration that is used for the exhalation valve  980 . Valve  980  is illustrated and includes a body  981 , an inlet  982 , ports  984   a  and  984   b  ( 984   b  shown only in the view of  FIG. 10F ), outlet ports  985  and a valve flap  986 . The flap valve  986  is rotatable about an axial member  988  to open and close a passageway between the ports  984   a ,  984   b  and outlet port  985 , denoted by the large arrow  989 . The micro pump  600  applies air through inlet  982  to close the flap valve  986 . In the context of  FIG. 10  and  FIG. 9C , the inlet  982  is coupled to an output of the micro pump, the ports  984   a ,  984   b  are coupled to the plugs  964   a ,  964   b  (with air passages) and the outlet is coupled to one or both of the outlets  968   a ,  968   b.    
     The valves can be of various configurations. For example, as discussed in my pending patent application Ser. No. 14/632,423 filed Feb. 26, 2015 and incorporated herein by reference a sliding valve (a “T valve”) can be used on output ports and a sliding valve (an “omega valve”) can be used on input ports to the chambers of the micro pump, e.g.,  200  ( FIG. 2B ). Recalling that the chamber  209  is produced from the pump body  204  and membranes  206  ( FIG. 2B ) (or end walls of the pump body). 
     Referring now to  FIGS. 11A and 11B , an alternative implementation  1000  of the micro pump with sliding valves is shown. Details are shown for an exemplary sliding valve  1010  (a “T” or “Tau” valve) used on output ports and a sliding valve  1020  (an “Omega valve”) used on input ports to the chambers e.g.,  209  of the micro pump, e.g.,  200  ( FIG. 2B ) are shown. The “T” or “Tau” valve has a movable member in the shape of a “T” (or the Greek letter “Tau”, whereas the Omega valve has a movable member in the shape of the Greek letter “Omega.” 
     Recalling that the chamber  209  is produced from the pump body  204  and membranes  206  ( FIG. 2B ) (or end walls of the pump body). In  FIG. 11A , a portion of the material  1000  that is used to produce the pump body  204  provides the T valve  1010  at what would be an output port of a micro pump chamber. The T valve  1010  includes a flat member  1012  that provides a valve to close off the output port and with the flat member  1012  connected to a stem member  1014  that resides in a compartment  1017  formed from regions  1018 . Outlets from the chamber are provided by regions  1016 . 
     In  FIG. 11A , another portion of the material  1000  that is used to produce the pump body  204  provides the omega valve  1020  at what would be an input port of a micro pump chamber. The omega valve  1020  includes a piston, like member  1022  that provides a stop for the omega shaped member  1024  that is somewhat semi-circular with horizontal arms  1024   a  that provides a valve to close off the input port and with the omega shaped member  1024  having vertical arms  1024   b . The omega shaped member is confined to the region (not referenced) form between the piston member  1022  and the omega member  1024  by the piston like member  1022 . Inlets from the chamber are provided by regions  1026 . 
     Referring now to  FIG. 11B  the etched body  1000 ′ has the sliding valve  1010  (“T valve”) on output ports and the sliding valve  1020  (“omega valve”) on input ports and which are formed by removing excess material from the material of the body guided by the etch lines  1002 , as shown, leaving each of the sliding valves  1010  and  1020  to move freely within very confined regions, according to pressure applied to the chamber but not being free to move outside of the confined regions. As shown in  FIG. 11B , dicing of the pump body along dicing lines defined by etch lines in corners will separate the piston like member  1022  from the body and the stem of the T member from the body. The T valve  1010  has the flat member  1012  close off the output port, and is confined in the region defined by  1016  and  1017 , whereas the mega valve  1020  is confined by the region  1026  and region  1027 . 
       FIGS. 11C and 11D  show the sliding valve  1010  (“T valve”) on output ports and the sliding valve  1020  (“omega valve”) on input ports at a higher magnification. 
     In some implementations, the micro pump systems can also be used to sense distance between membranes by measuring capacitance between the membranes. The micro pumps include electrodes, each pair of which forming an electrostatic actuator, which is effectively a variable capacitor having two conductive plates, i.e., the electrodes, spaced apart at some distance. When a voltage is applied across the two electrodes, the electrodes move towards or away from each other. As the distance between the electrodes changes, so does the capacitance. The capacitance increases as the electrodes move closer and decreases as the electrodes move apart. Accordingly, the capacitance between a pair of electrodes can provide information about the distance between the pair. 
     In some implementations, the information can be applied to determining a number of parameters of the system. For example, quantities including pressure, volume, flow rate, and density can be measured. A sacrificial filling material is used in R2R processing described below. In some implementations, solvents are used in the manufacturing process, which may place additional requirements on the various other materials of the micro pump. In some implementations electrical circuit components are printed into the membranes. A release material is used for enabling flap movement of the flap valves. In general, while certain materials have been specified above, other materials having similar properties to those mentioned could be used. 
     Roll to Roll Processing for Producing Micro Pumps and Flap Valves 
     Referring to  FIG. 12 , a conceptual view of a roll to roll processing line is illustrated. The processing line comprises several stations, e.g., station  1  to station n (that can be or include enclosed chambers) at which deposition, patterning, and other processing occurs. Processing viewed at a high level thus can be additive (adding material exactly where wanted) or subtractive (adding material and removing material in places where wanted). Deposition processing includes evaporation, sputtering, and/or chemical vapor deposition (CVD), as needed, as well as printing. The patterning processing can include depending on requirements techniques such as scanning laser and electron beam pattern generation, machining, optical lithography, gravure and flexographic (offset) printing depending on resolution of features being patterned. Ink jet printing and screen printing can be used to put down functional materials such as conductors. Other techniques such as imprinting and embossing can be used. 
     The original raw material roll is of a web of flexible material. In roll to roll processing the web of flexible material can be any such material and is typically glass or a plastic or a stainless steel. While any of these materials (or others) could be used, plastic has the advantage of lower cost considerations over glass and stainless steel and is a biocompatible material for production of the micro-pump when used in the CPAP type (continuous positive airway pressure) breathing device ( FIG. 9 ). In other applications of the micro-pump, e.g., as a cooling component for electronic components other materials such as stainless steel or other materials that can withstand encountered temperatures would be used, such as Teflon and other plastics that can withstand encountered temperatures. 
     Referring now to  FIG. 12A , for the structure shown in  FIGS. 2A-2D , stations within a roll to roll processing structure are set up according to the processing required. Thus, while the pump end cap and top caps could be formed on the web or plastic sheet of  FIG. 12 , in one implementation the end and top caps are provided after formation of the micro-pump stack, as will be described. 
     The plastic web is used to support the pump body  204  ( FIG. 2B ) by a deposition of material on the web at a deposition station  280  followed by patterning station  282 . The pump body  204  and stopper  218  and a flap  220  for flap valves  214  ( FIG. 2B ) are formed in the pump body  204  at a forming station  284 . In one implementation a station  286  is provided to deposit sacrificial material to hold the flaps to the body. The web having the pump body  204  and formed flaps  220  for flap valves  214  ( FIG. 2A ) has a membrane deposited over the pump body  204  at a station  290 . Over the membrane  206  is deposited an electrode  210  at deposition station  292  which is patterned at patterning station  294 . 
     The flap  220  has one end  222  attached to the pump body  204  and another end  224  movable relative to the stopper  218  and the pump body  204 . The flaps are formed in the pump body using the same material as used for the pump body. The material for the flaps  220 ,  232  needs to be strong or stiff enough to hold its shape, yet elastic enough to allow the flaps  220 ,  232  to move as desired. The material is etchable or photo sensitive so that its features can be defined and machined/developed. The material interacts, e.g., adheres, with the other materials in the micro pump, e.g., via polymeric or ultrasonic welding. Furthermore, the material is electrically non-conductive. Examples of suitable materials include SU8 (negative epoxy resist), and PMMA (Polymethyl methacrylate) resist. 
     Over the pump body is applied a membrane sheet  206  with patterned electrodes  210  supported on the membrane  206 . Electrical interconnects for conducting the drive voltages to the electrodes  206  on each membrane are provided by depositing conductive materials, e.g., gold, silver, and platinum layers (or conductive inks such as silver inks and the like). In some implementations some of the electrical circuit components are printed onto the membranes. 
     In manufacturing the micro pump, the sacrificial filling material that can be employed is, e.g., polyvinyl alcohol (PVA). The sacrificial filling material can be used, if needed, to support the membrane over the pump body during processing. Solvents then would be used in the manufacturing process to subsequently remove this sacrificial filling material. 
     The roll having the micro-pump units (pump body and membrane with electrode and electrical connections) are diced and the micro-pump units are collected, assembled into stacks of micro-pump units, and packaged by including the end and top caps to provide micro-pumps (e.g., of  FIG. 2A ). Depending upon the layout of the pump units on the web it may be possible to fold the web of the pump units into a stack of pump units, with electrodes provided on the membrane layer. 
     The membrane material is required to bend or stretch back and forth over a desired distance and thus should have elastic characteristics. The membrane material is impermeable to fluids, including gas and liquids, is electrically non-conductive, and possesses a high breakdown voltage. Examples of suitable materials include silicon nitride and Teflon. 
     The material of the electrodes is electrically conductive. The electrodes do not conduct significant current. The material can have a high electrical resistance, although the high resistance feature is not necessarily desirable. The electrodes are subject to bending and stretching with the membranes, and therefore, it is desirable that the material is supple to handle the bending and stretching without fatigue and failure. In addition, the electrode material and the membrane material adhere well, e.g., do not delaminate from each other, under the conditions of operation. Examples of suitable materials include, e.g., gold, silver, and platinum layers (or conductive inks such as silver inks and the like). A release material can be used for allowing for valve movement. Suitable release materials include, e.g., the sacrificial filling material mentioned above. 
     Referring to  FIGS. 13A-13D , an alternative roll to roll processing approach to provide the modularized micro pump  200  ( FIG. 2A ) is shown. The micro-pump  200  has features that are movable in operation and may be release-able from carriers during manufacture. These features include the membrane (which flexes) and the flaps (on flap valves that bend or swing) or alternatively the slide-able valves of ( FIGS. 12A-12D ) that can be released. In this discussion the focus will be on valves having features that slide and be released (the Tau and Omega portions of the Tau and Omega valves of  FIGS. 12A-12D ). Other types of microelectromechanical systems that can be produced in the roll to roll processing line using the techniques disclosed herein would have other features that are movable in operation, e.g., rods or gears that are examples of features that slide and rotate, respectively. These features are also released during processing, as described below. 
     The micro pump  260  is fabricated using roll to roll processing where a raw sheet (or multiple raw sheets) of material is passed through plural stations to have features applied to the sheet (or sheets) and the sheet (or sheets) are subsequently taken up to form parts of the repeatable composite layers (See  FIGS. 2A-2D ) to ultimately produce a composite sheet of fabricated micro-pumps (or other structures having movable and/or release-able features). In the implementation of micro pump of  FIGS. 12A-12B , the roll to roll processing provides features that are freely movable (e.g., free to move) within constructed microelectromechanical systems. 
     Referring to  FIG. 13A , a sheet  304  of a flexible material such as a glass or a plastic or a stainless steel is used as a web. For the particular implementation of the micro-pump (either the micro-pump  200  ( FIGS. 2A-2D ) with sliding valves or with flap valves), the material is a plastic sheet, e.g., Polyethylene terephthalate (PET), which is provided with a layer  304   a  of metal e.g., aluminum (Al) over a major surface of the sheet  304 . 
     The sheet  304  is a 50 micron thick sheet of PET (Teflon) that coated with a thin metal layer  304   a  of aluminum having a 100 A° (Angstroms) thickness. Other thicknesses could be used (e.g., the sheet  304  could have a thickness between, e.g., 25 microns and 250 microns (or greater) and the thickness of the layer  304   a  can be 50 A° to 500 A° (or greater). The thicknesses are predicted on desired properties of the microelectromechanical system to be constructed and the handling capabilities of roll to roll processing lines. These considerations will provide a practical limitation on the maximum thickness. Similarly, the minimum thicknesses are predicted on the desired properties of the microelectromechanical system to be constructed and the ability to handle very thin sheets in roll to roll processing lines. 
     For the example where the microelectromechanical system is the micro pump, the layers would have thicknesses as mentioned above approximately 50 microns for the pump body and 5 microns for the membrane elements of the micro pump  200 . However, other thicknesses are possible even for the micro pump. The metal layer  304   a  is provided by various approaches, such as evaporation or other techniques. Such metalized films are also commercially available. 
     The sheet  304  from a roll (not shown) with the layer  304   a  of metal is patterned at an ablation station, e.g., a laser ablation station  1 . A mask (not shown) is used to configure the laser ablation station to remove the metal layer  304   a  from those portions of the sheet  304  that will be used to form the micro pump units, i.e., the body, the regions  1018 , the regions  1022  and  1024   b , while leaving metal  304 ′ only on portions of the sheet that will ultimately become movable parts, which in the case of the micro pump with sliding valves (as shown in  FIGS. 11A-11D ) are the “T” (or Tau) ( 1017 ,  FIG. 11C ) and the “omega” shaped members ( 1026 ,  FIG. 11D ) of the Tau and Omega valves respectively, as shown in detail in  FIG. 13A-1 . Optionally, the metal  304 ′ can also be left on those extraneous portions of the sheet where the various structures are not fabricated, in order to same time/expense in unnecessary ablation as shown in detail in  FIG. 13A-1 . 
     The metal left on the sheet portions that will become Tau portion of the Tau valve and the Omega portion of the Omega valve permit those features to move within the respective valves. This technique relies on the recognition that during lamination of plastic layers as discussed below, the plastic will not laminate to the metal based on conditions that will be employed by subsequent lamination techniques. However, under these conditions the plastic will stick to underlying plastic. The defined conditions include heat, pressure and time that during lamination are sufficient to cause the plastic to stick to the underlying plastic by an electrostatic mechanism without melting the PET. 
     Referring now to  FIG. 13B , the sheet  304  with the metal left  304   a ′ on sheet portions that will align to the T portion ( 1017 ,  FIG. 12D ) of the T valve and the omega portion ( 1026 ,  FIG. 12D ) of the omega valve, and optionally on the extraneous portions, is micro-machined. A second mask (not shown) is used to configure a second laser ablation station to define or form the compartment and valve members (denoted as regions  306  in  FIG. 13B ) of the micro pump of  FIGS. 11A-11D , as well as alignment holes (not shown but will be discussed below). Vias are also provided for electrical connections, as shown. The micro-machining ablates away the plastic to form the compartment of the micro pump while leaving the frame portion of the pump body and also forms the containment structures for the valves as generally shown for item  306 ′. 
     Referring now to  FIG. 13C , the sheet  304  with the defined features of the T portion ( 1017 ,  FIG. 12D ) of the T valve and the omega portion ( 1026 ,  FIG. 12D ) of the omega valve, and the compartment is laminated at a lamination station to a second sheet  308 , e.g., 5 micron thick sheet of PET, with a second metallic layer  310  of Al of 100 A on a top surface of the sheet. This second sheet  308  forms the membranes over the pump bodies provided by the defined features of the compartment and valve regions. The second sheet is also machined to provide the alignment holes (not shown) prior to or subsequent to coating of the metallic layer. 
     Prior to lamination of the second sheet  308  to the first sheet  304 , the second sheet  308  is also provided with several randomly dispersed holes (not shown) over some areas that will be in alignment with the pump bodies structures. These randomly dispersed holes are used by a machine vision system to reveal and recognize underlying features of the pump body units on the first sheet  304 . Data is generated by noting the recognized features in the first sheet through the random holes. These data will be used to align a third ablation station when forming electrodes from the layer over the pump bodies (discussed below) and metallic pads in regions over the Tau and Omega features. 
     The second sheet  308  is laminated to and thus sticks (or adheres) to the first sheet  304  in areas where there is plastic on the first sheet  304  and plastic on the second sheet  308 , but does not adhere or stick to the first sheet  304  where there is metal on the first sheet  304  and plastic on the second sheet  308 . This selective sticking results because the lamination conditions discussed above. This permits the movable members in the micro pump to freely move, e.g., the Tau and Omega structures of  FIGS. 12A-12D . 
     At this point, a composite sheet  310  of repeatable units of the micro pump, e.g., pump body and movable and releasable features, with membranes are formed, but without electrodes formed from the layer on the membrane. This selective sticking provided by the use of metal on features that would come in contact with the sheet can be used to provide other movable features such as flaps on flap valves, beams, cantilevered structures, gears, etc., in other microelectromechanical systems that include such movable features. 
     The machine vision system produces a data file that is used by the laser ablation system in aligning a third laser ablation station with a fourth mask such that a laser beam from the laser ablation system provides the electrodes  210  ( FIG. 2B ) according to the fourth mask, with the electrodes in registration with the corresponding portions of the pump bodies. The electrodes are formed by ablating away the metal in regions that are not part of the electrodes and conductors, leaving isolated electrodes and conductors on the sheet. The registration of the patterned electrodes to the pump body is thus provided by using the machine vision system to observe features on the front side of the laminated structure providing positioning data that the laser ablation system uses to align a laser beam with the fourth mask, using techniques commonly found in the industry. 
     Referring now to  FIG. 13D , the composite sheet  310  is fed to a third laser ablation station, to form the electrodes by ablating the 100 A° Al layer deposited on the second sheet that formed the membrane. The composite sheet  310  is patterned according to a fourth mask ( FIG. 14 ) to define the electrodes over corresponding regions of the pump body. The third ablation station ablates away metal from the second layer leaving isolated electrodes on the sheet. 
     Referring now to  FIG. 14 , the fourth mask  320  used to configure the third laser ablation station to provide the electrodes  210  ( FIG. 2B ) is shown. This fourth mask can be viewed as showing the electrodes  210  ( FIG. 2B ) and conductors  212  ( FIG. 2B ) on the membrane, alignment holes  334 , and cut lines  336 . This composite sheet  320  with the electrodes ( FIG. 13D ) is fed to a station (not shown) where the sheet is cut along cut lines  336 , as shown in  FIG. 14 . The alignment holes  334  provided from each of the processing steps of  FIGS. 13A-13D  are used to provide a mechanism to align each of dies cut from these sheets to produce a stack of such pump bodies as in  FIG. 2D . 
     A jig (not shown) that can comprises vertical four posts mounted to a horizontal base is used to stack individual ones of the cut dies. On the jig an end cap (e.g., a 50 micron PET sheet with a metal layer) is provided and over the end cap a first repeatable unit is provided. The repeatable unit is spot welded (applying a localized heating source) to hold the unit in place on the jig. As each repeatable unit is stacked over a previous repeatable unit that unit is spot welded. The stack is provided by having the T values on one side of the stack and the Omega valves on the other of the stack, and staggered resulting from arrangement of the valves so as to have a solid surface separating each of the values in the stack (See  FIG. 2D ). Once a stack is completed, a top cap (not shown) can be provided. The stack unit is sent to a lamination station not shown, where the stack is laminated, laminating all of the repeatable units and caps together. The end cap and top cap can be part of the packaging as well. Otherwise sets of repeatable units can be laminated in pairs. 
     The modularized micro pump  260  is comprised of module layers to form end compartments of the pump  260 . The module layers each include a pump end cap forming a fixed pump wall (similar to walls  106 ,  108   FIGS. 1A, 1B ). An electrode is attached to the pump end cap for activating the compartment. The electrode includes a lead (not shown) to connect to a drive circuit (not shown). After lamination of the stack, the stack units are diced to form individual micro pumps. 
     Other stacking techniques for assembly are possible with or without the alignment holes  334 . 
     Elements of different implementations described herein may be combined to form other embodiments not specifically set forth above. Elements may be left out of the structures described herein without adversely affecting their operation. Furthermore, various separate elements may be combined into one or more individual elements to perform the functions described herein. Other embodiments are within the scope of the following claims.