GANGING ELECTROKINETIC PUMPS
An electrokinetic system includes a first electrokinetic pump, a second electrokinetic pump, a reservoir having delivery fluid therein, and a controller. The first electrokinetic pump is configured to provide a first range of flow rates. The second electrokinetic pump is configured to provide a second range of flow rates. The second range includes flow rates that are greater than the flow rates of the first range. The reservoir is fluidically attached to the first electrokinetic pump and the second electrokinetic pump. The controller is configured to apply voltage to one of the first or second electrokinetic pumps and then apply voltage to the other of the first or second electrokinetic pumps so as to vary the flow rate range of delivery fluid pump from the reservoir.
This application claims priority to U.S. Provisional Application No. 61/482,949, filed May 5, 2011, and titled “GANGING ELECTROKINETIC PUMPS,” which is herein incorporated by reference in its entirety.
INCORPORATION BY REFERENCEAll publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.
FIELDThis application relates generally to methods for delivery a volume of fluid with a pump system. More specifically, the disclosure relates to a pump system including a plurality of electrokinetic pumps ganged together.
BACKGROUNDElectrokinetic (“EK”) or electro-osmotic manipulations of fluids represent the state-of-the art in controlled, high precision, small volume fluid transport and handling. Electro-osmosis involves the application of an electric potential to an electrolyte, in contact with a dielectric surface, to produce a net flow of the electrolyte.
EK pumps have widespread and wide ranging applications, such as for chemical analysis, drug delivery, and analyte sampling. However, there are several design challenges associated with using EK pumps, such as obtaining a high flow rate, a large range of flow rates from a single EK pump system, and achieving continuous flow.
Accordingly, the present disclosure is directed to a pump system having a plurality of EK pumps ganged together to achieve a high flow rates, a large range of flow rates, and/or substantially continuous flow.
SUMMARY OF THE DISCLOSUREIn general, in one aspect, an electrokinetic system includes a first electrokinetic pump, a second electrokinetic pump, a reservoir having delivery fluid therein, and a controller. The first electrokinetic pump is configured to provide a first range of flow rates. The second electrokinetic pump is configured to provide a second range of flow rates. The second range includes flow rates that are greater than the flow rates of the first range. The reservoir is fluidically attached to the first electrokinetic pump and the second electrokinetic pump. The controller is configured to apply voltage to one of the first or second electrokinetic pumps and then apply voltage to the other of the first or second electrokinetic pumps so as to vary the flow rate range of delivery fluid pump from the reservoir.
In general, in one aspect, a method of pumping fluid includes applying voltage with a controller to a first electrokinetic pump to pump delivery fluid from a reservoir at a first flow rate; and applying voltage with the controller to a second electrokinetic pump to pump delivery fluid from the reservoir at a second flow rate, the second flow rate different than the first flow rate.
These and other embodiments can include one or more of the following features. The flow rate range of the electrokinetic system can be from approximately 0.0001 mL/hr to 1,200 mL/hr, such as 0.0001 mL/hr to 1,000 mL/hr, for example 0.01 mL/hr to 30 mL/hr. The system can further include a third electrokinetic pump configured to provide a third range of flow rates. The third range can include flow rates that are greater than the flow rates of the second range. The reservoir can be fluidically connected to the third electrokinetic pump, and wherein the controller is configured to apply voltage to one of the first or second or third electrokinetic pumps and then apply voltage to the another of the first or second electrokinetic pumps so as to vary the flow rate range of delivery fluid pumped from the reservoir. The flow range of the first electrokinetic pump can be approximately 0.01-5 mL/hr, and the flow rate of second electrokinetic pump can be approximately 0.1-15 mL/hr. The first and second pumps can be electrically connected in parallel. The first electrokinetic pump can include a first pressure sensor, and the second electrokinetic pump can include a second pressure sensor. The first electrokinetic pump can include a first check valve, and the second electrokinetic pump can include a second check valve. The controller can be configured to apply voltage to both of the first and second electrokinetic pumps simultaneously to increase the flow rate of delivery fluid pumped from the reservoir.
In general, in one aspect, an electrokinetic system includes a first electrokinetic pump and a second electrokinetic pump, a reservoir having delivery fluid therein, and a controller. The reservoir is fluidically attached to the first electrokinetic pump and the second electrokinetic pump. The controller is configured to apply voltage in a first cycle to the first electrokinetic pump and to apply voltage in a second cycle to a second electrokinetic pump. The controller is further configured to stagger the start-time of the first and second cycles so as to provide substantially continuous flow of the delivery fluid from the reservoir.
In general, in one aspect, a method of pumping includes applying voltage in a first cycle to a first electrokinetic pump and applying voltage in a second cycle to a second pump. The first and second electrokintic pumps are fluidically connected to a reservoir having a delivery fluid therein. The start-time of the second cycle is delayed relative to the start-time of the first cycle so as to provide substantially continuous flow of the delivery fluid from the reservoir.
These and other embodiments can include one or more of the following features. The system can further include a third electrokinetic pump and a fourth electrokinetic pump. The reservoir can be fluidically attached to the third and fourth electrokinetic pumps. The controller can be configured to apply voltage in a third cycle to the third electrokinetic pump and to apply voltage in a fourth cycle to the fourth electrokinetic pump. The controller can be configured to stagger the start-times of the first, second, third, and fourth cycles so as to provide substantially continuous flow of the delivery fluid from the reservoir. The controller can be configured to synchronize the cycles such that the first cycle includes an intake or outtake stroke only when the second cycle includes a zero-voltage phase, the second cycle includes an intake or an outtake stroke only when the first cycle includes a zero-voltage phase, the third cycle includes an intake or an outtake stroke only when the fourth cycle includes a zero-voltage phase, the fourth cycle includes an intake or an outtake stroke only when the third cycle includes a zero-voltage phase. The controller can be further configured to synchronize the cycles such that the first cycle includes an intake stroke when the third cycle includes an outtake stroke, and the third cycle includes an intake stroke when the first cycle includes an outtake stroke. The controller can be configured to synchronize the cycles such that the first cycle includes an intake stroke while the second cycle includes an intake stroke. The third cycle can include an intake stroke while the second cycle includes an intake stroke. The fourth cycle can include an intake stroke while the third cycle includes an intake stroke. The first electrokinetic pump can be connected to a first electrokinetic engine, and the first electrokinetic engine can be further connected to a third electrokinetic pump. The second electrokinetic pump can be connected to a second electrokinetic engine, and the second electrokinetic engine can be further connected to a fourth electrokinetic pump. The first and second engines can be reciprocating engines. The instantaneous flow rate can never drop to zero during the delivery of fluid. The instantaneous flow rate of the system can vary by less than 20% from a target flow rate, such as less than 10%, for example less than 5%.
The novel features of the invention are set forth with particularity in the claims that follow. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:
Certain specific details are set forth in the following description and figures to provide an understanding of various embodiments of the invention. Certain well-known details, associated electronics and devices are not set forth in the following disclosure to avoid unnecessarily obscuring the various embodiments of the invention. Further, those of ordinary skill in the relevant art will understand that they can practice other embodiments of the invention without one or more of the details described below. Finally, while various processes are described with reference to steps and sequences in the following disclosure, the description is for providing a clear implementation of particular embodiments of the invention, and the steps and sequences of steps should not be taken as required to practice this invention.
Referring to
The EK pump 101 includes a delivery chamber 122 and a movable member 113 having a first edge 112 contacting the delivery chamber 122 and a second edge 111 contacting the second chamber 104. In some embodiments, the first and second edges 112, 111 are flexible diaphragms having a mechanical piston therebetween. In other embodiments, the first and second edges 112, 111 are flexible diaphragms having a gel material therebetween. Gel couplings are described further in U.S. Provisional Patent Application No. 61/482,889, filed May 5, 2011, and titled “GEL COUPLING FOR ELECTROKINETIC DELIVERY SYSTEMS,” and U.S. patent application Ser. No. ______, filed herewith, and titled “GEL COUPLING FOR ELECTROKINETIC DELIVERY SYSTEMS,” the contents of both of which are incorporated herein by reference. In other embodiments, the first and second edges 112, 111 are edges of a single flexible member or diaphragm.
The delivery chamber 122 can include a delivery fluid, such as a drug or medication, e.g., insulin or pain management medications, or a cleansing fluid, such as a wound cleansing fluid, supplied to the delivery chamber 122 from a fluid reservoir 141. An inlet check valve 142 between the fluid reservoir 141 and delivery chamber 122 can control the supply of delivery fluid to the delivery chamber 122, while an outlet check valve 144 can control the delivery of delivery fluid from the delivery chamber 122, such as to a patient. A first pressure sensor 152 and a second pressure sensor 154 can monitor the flow of fluid from the system. Further, a flow restrictor 160 can be present in the pump 101 to produce a pressure differential between sensors 152, 154 so as to provide a mechanism for measuring the flow of the fluid. Mechanisms for monitoring fluid flow are described further in U.S. Provisional Patent Application No. 61/482,960, filed May 5, 2011, and titled “SYSTEM AND METHOD OF DIFFERENTIAL PRESSURE CONTROL OF A RCIPROCATING ELECTROKINETIC PUMP,” and U.S. patent application Ser. No. ______, filed herewith, and titled “SYSTEM AND METHOD OF DIFFERENTIAL PRESSURE CONTROL OF A RCIPROCATING ELECTROKINETIC PUMP.”
In use, the electrokinetic assembly 100 works by producing electrokinetic or electroostmostic flow. A voltage, such as a positive voltage, is applied to the electrodes 108a, 108b, which causes the engine fluid to move from the second chamber 104 to the first chamber 102. The engine fluid may flow through or around the electrodes 108a and 108b when moving between the chambers 104, 102. The flow of fluid causes the movable member 110 to be pushed out of the chamber 102 and the movable member 113 to be pulled into chamber 104. As a result of the movement of the movable member 113, delivery fluid is pulled from the reservoir 141 into the delivery chamber 122. The movement of delivery fluid from the reservoir into the delivery chamber 122 is called the “intake stroke” of the pump cycle. When the opposite voltage is applied, such as a negative voltage, fluid moves from the first chamber 102 to the second chamber 104. The movement of engine fluid between chambers causes the movable member 110 to be pulled into the first chamber 102 and the movable member 113 to expand to compensate for the additional volume of engine fluid in the second chamber 104. As a result, delivery fluid in the chamber 122 is pushed out of the chamber 122 and delivered, such as to a patient, through the outlet check valve 144. The delivery of fluid is called the “outtake stroke” of the pump cycle. Although the exemplary assemblies and systems described below are configured such that a positive voltage corresponds to the intake stroke and a negative voltage corresponds to an outtake stroke, it is to be understood that the opposite configuration is also possible—i.e., that a negative voltage corresponds to an intake stroke and a positive voltage corresponds to an outtake stroke. A controller can be used to control the voltage applied to the electrodes 108a, 108b.
Referring to
The electrokinetic pump assembly 100 can be configured to stop pumping in a particular direction, i.e. with negative or positive current, prior to the occurrence of a Faradaic process in the liquid. Accordingly, the electrodes will advantageously not generate gas or significantly alter the pH of the pump fluid. The set-up and use of various EK pump assemblies are further described in U.S. Pat. Nos. 7,235,164 and 7,517,440, the contents of which are incorporated herein by reference.
Referring to
Referring to
In use, referring to
Advantageously, by ganging pump assemblies in parallel as described with reference to
Referring to
EK assembly 600a can have a different range of flow rates than EK assembly 600b. For example, EK assembly 600b can be configured to run at greater flow rates than EK assembly 600a. Although
In use, referring to
Advantageously, by ganging together pumps of different flow rate ranges in the configuration shown in
Moreover, in some embodiments, the controller 691 can run both EK assemblies 600a, 600b at the same time, thereby increasing the total flow rate range achievable by the EK pump system 699. By ganging EK assemblies of different sizes together in a single EK pump system and running the pumps simultaneously, the accuracy of the system can be increased relative to using a single EK assembly having a large flow rate. That is, each EK pump system has an optimal delivery volume where the EK engine is most efficient. For example, a large delivery pump that has only a small percentage error can still cause significant errors if being used to deliver small volumes. Moreover, often the corresponding system components, such as the sensors and check valves, can be dialed with a resolution that matches the optimal volume to achieve better accuracy. Further, timing errors caused by slow responsiveness of larger components can be minimized by controlling smaller pumps to move small amounts of liquid rather than using a large pump to deliver small volumes of liquid. Accordingly, a ganged pumped system having pumps of different volumes can advantageously provide a more robust response range based upon the optimal ranges of the pumps used.
Referring to
The slave controllers 895a, 895b can, for example, perform feedback measurements, control loop calculations, and current controls. The master controller 891, in contrast, can be configured to align the pump cycles of each of the assemblies 800a, 800b to achieve the desired flow profile for the EK pump system 899. Communication between the master controller 891 and slave controllers 895a, 895b can include which slave is controlling delivery at a particular time, what volume of fluid is delivered, and any errors in delivery.
In use, referring to
In one embodiment, shown in
In another embodiment, shown in
In some embodiments, the controller 891 can run two or more cycles concurrently so as to increase flow.
Advantageously, the system set-up of
Further, by including overlapping boluses as described above with respect to
Referring to
Referring to
As for additional details pertinent to the present invention, materials and manufacturing techniques may be employed as within the level of those with skill in the relevant art. The same may hold true with respect to method-based aspects of the invention in terms of additional acts commonly or logically employed. Also, it is contemplated that any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein. Likewise, reference to a singular item, includes the possibility that there are plural of the same items present. More specifically, as used herein and in the appended claims, the singular forms “a,” “and,” “said,” and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. Unless defined otherwise herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The breadth of the present invention is not to be limited by the subject specification, but rather only by the plain meaning of the claim terms employed.
Claims
1. An electrokinetic pump system, comprising:
- a reservoir configured to have a delivery fluid therein;
- a first electrokinetic pump assembly fluidically connected to the reservoir and configured to pump the delivery fluid from the reservoir at a first range of flow rates;
- a second electrokinetic pump assembly fluidically connected to the reservoir and configured to pump the delivery fluid from the reservoir at a second range of flow rates, the second range including flow rates that are greater than the flow rates of the first range; and
- a controller configured to apply voltage to one of the first or second electrokinetic pump assemblies and then apply voltage to the other of the first or second electrokinetic pump assemblies so as to vary the flow rate of delivery fluid pumped by the electrokinetic pump system.
2. The electrokinetic pump system of claim 1, wherein a total flow rate range of the system is between approximately 0.0001 ml/hr and 1,200 ml/hr.
3. The electrokinetic pump system of claim 2, wherein the total flow rate range of the system is between approximately 0.0001 ml/hr and 1,000 ml/hr.
4. The electrokinetic pump system of claim 3, wherein the total flow rate range of the system is between approximately 0.01 ml/hr and 30 ml/hr.
5. The electrokinetic system of claim 1, further comprising a third electrokinetic pump assembly fluidically connected to the reservoir and configured to provide a third range of flow rates, the third range of flow rates including flow rates that are greater than the flow rates of the second range, wherein the controller is configured to apply voltage to one of the first or second or third electrokinetic pump assemblies and then apply voltage to the another of the first or second electrokinetic pump assemblies so as to vary the flow rate of delivery fluid pumped by the electrokinetic pump system.
6. The electrokinetic system of claim 1, wherein the flow rate range of the first electrokinetic pump assembly is between approximately 0.01 and 5 ml/hr and the flow rate range of the second electrokinetic pump assembly is between approximately 0.1 ml/hr and 15 ml/hr.
7. The electrokinetic system of claim 1, wherein the first and second pump assemblies are electrically connected in parallel.
8. The electrokinetic system of claim 1, wherein the first electrokinetic pump assembly includes a first pressure sensor configured to detect a flow rate of delivery fluid pumped with the first electrokinetic pump assembly, and wherein the second electrokinetic pump assembly includes a second pressure sensor configured to detect a flow rate of delivery fluid pumped with the second electrokinetic pump assembly.
9. The electrokinetic system of claim 1, wherein the first electrokinetic pump assembly includes a first check valve to control the flow rate of delivery fluid pumped from the first electrokinetic pump assembly, and wherein the second electrokinetic pump assembly includes a second check valve configured to control the flow rate of delivery fluid pumped from the second electrokinetic pump assembly.
10. The electrokinetic system of claim 1, wherein the controller is further configured to apply voltage to both of the first and second electrokinetic pump assemblies simultaneously to increase the flow rate of delivery fluid pumped by the electrokinetic pump system.
11. A method of pumping fluid in an electrokinetic pump system, comprising:
- applying voltage with a controller to a first electrokinetic pump assembly to pump delivery fluid from a reservoir at a first flow rate; and
- applying voltage with the controller to a second electrokinetic pump assembly to pump delivery fluid from the reservoir at a second flow rate, the second flow rate different than the first flow rate.
12. The method of claim 11, wherein a total flow rate range of the electrokinetic pump system is between approximately 0.0001 ml/hr and 1,200 ml/hr.
13. The method of claim 12, wherein the total flow rate range of the electrokinetic pump system is between approximately 0.0001 ml/hr and 1,000 ml/hr.
14. The method of claim 13, wherein the total flow rate range of the electrokinetic pump system is between approximately 0.01 ml/hr to 30 ml/hr.
15. The method of claim 11, further comprising applying voltage with the controller to a third electrokinetic pump assembly to pump delivery fluid from the reservoir at a third flow rate, the third flow rate different than the first and second flow rates.
16. The method of claim 11, wherein a flow rate range of the first electrokinetic pump assembly is between approximately 0.01 ml/hr and 5 ml/hr, and wherein a flow rate range of the second electrokinetic pump assembly is between approximately 0.1 ml/hr and 15 ml/hr.
17. The method of claim 11, wherein the first and second electrokinetic pump assemblies are electrically connected in parallel.
18. The method of claim 11, further comprising measuring the flow rate of delivery fluid pumped by the first electrokinetic pump assembly with a first pressure sensor and measuring the flow rate of delivery fluid pumped by the second electrokinetic pump assembly with a second pressure sensor.
19. The method of claim 11, further comprising controlling the flow of delivery fluid pumped by the first electrokinetic pump assembly with a first check valve and controlling the flow of delivery fluid pumped by the second electrokinetic pump assembly with a second check valve.
20. The method of claim 11, wherein the voltage is applied with the controller to the first and second electrokinetic pump assemblies simultaneously to increase the flow rate of delivery fluid pumped by the electrokinetic pump system.
21. An electrokinetic pump system comprising:
- a reservoir configured to have a delivery fluid therein;
- a first electrokinetic pump assembly fluidically connected to the reservoir and configured to pump the delivery fluid from the reservoir;
- a second electrokinetic pump assembly fluidically connected to the reservoir and configured to pump the delivery fluid from the reservoir; and
- a controller configured to apply voltage in a first cycle to the first electrokinetic pump assembly and to apply voltage in a second cycle to a second electrokinetic pump assembly, the controller configured to stagger the start-time of the first and second cycles so as to provide substantially continuous flow of the delivery fluid from the electrokinetic pump system.
22. The electrokinetic pump system of claim 21, further comprising a third electrokinetic pump and a fourth electrokinetic pump, wherein the reservoir is fluidically attached to the third and fourth electrokinetic pumps, and wherein the controller is configured to apply voltage in a third cycle to the third electrokinetic pump and to apply voltage in a fourth cycle to the fourth electrokinetic pump, the controller configured to stagger the start-times of the first, second, third, and fourth cycles so as to provide substantially continuous flow of the delivery fluid pumped from the electrokinetic pump system.
23. The electrokinetic pump system of claim 22, wherein the controller is configured to synchronize the cycles such that the first cycle includes an intake or outtake stroke only when the second cycle includes a zero-voltage phase, the second cycle includes an intake or an outtake stroke only when the first cycle includes a zero-voltage phase, the third cycle includes an intake or an outtake stroke only when the fourth cycle includes a zero-voltage phase, the fourth cycle includes an intake or an outtake stroke only when the third cycle includes a zero-voltage phase.
24. The electrokinetic pump system of claim 23, wherein the controller is further configured to synchronize the cycles such that the first cycle includes an intake stroke when the third cycle includes an outtake stroke, and the third cycle includes an intake stroke when the first cycle includes an outtake stroke.
25. The electrokinetic pump system of claim 21, wherein the controller is configured to synchronize the cycles such that the first cycle includes an intake stroke while the second cycle includes an intake stroke.
26. The electrokinetic pump system of claim 25, wherein the third cycle includes an intake stroke while the second cycle includes an intake stroke.
27. The electrokinetic pump system of claim 26, wherein the fourth cycle includes an intake stroke while the third cycle includes an intake stroke.
28. The electrokinetic pump system of claim 21, wherein the first electrokinetic pump assembly includes a first electrokinetic engine and two electrokinetic pumps, and wherein the second electrokinetic pump assembly includes a second electrokinetic engine and two additional electrokinetic pumps, the first and second engines being reciprocating engines.
29. The electrokinetic pump system of claim 1, wherein the controller is configured such that an instantaneous flow rate of the delivery fluid pumped from the electrokinetic pump system never drops to zero during pumping of the delivery fluid.
30. The electrokinetic pump system of claim 21, wherein the controller is configured such that an instantaneous flow rate delivery fluid pumped from the electrokinetic pump system varies by less than 20% from a target flow rate.
31. The electrokinetic pump system of claim 30, wherein the controller is configured such that the instantaneous flow rate varies by less than 10%.
32. The electrokinetic pump system of claim 31, wherein the controller is configured such that the instantaneous flow rate varies by less than 5%.
33. A method of pumping fluid with an electrokinetic pump system, comprising:
- applying voltage in a first cycle to a first electrokinetic pump assembly to pump delivery fluid from a reservoir with the first electrokinetic pump assembly;
- applying voltage in a second cycle to a second electrokinetic pump assembly to pump delivery fluid from the reservoir with the second electrokinetic pump assembly;
- wherein the start-time of the second cycle is delayed relative to the start-time of the first cycle so as to provide substantially continuous flow of the delivery fluid from the electrokinetic pump system.
34. The method of claim 33, further comprising applying voltage in a third cycle to a third electrokinetic pump assembly to pump delivery fluid from the reservoir with the third electrokinetic pump assembly and applying voltage in a fourth cycle to a fourth electrokinetic pump assembly to pump delivery fluid from the reservoir with the fourth electrokinetic pump assembly, wherein the start-times of third and fourth cycles are delayed relative to the start-time of the first and second cycle so as to provide substantially continuous flow of the delivery fluid from the electrokinetic pump system.
35. The method of claim 34, further comprising synchronizing the cycles such that the first cycle includes an intake or outtake stroke only when the second cycle includes a zero-voltage phase, the second cycle includes an intake or an outtake stroke only when the first cycle includes a zero-voltage phase, the third cycle includes an intake or an outtake stroke only when the fourth cycle includes a zero-voltage phase, the fourth cycle includes an intake or an outtake stroke only when the third cycle includes a zero-voltage phase.
36. The method of claim 35, further comprising synchronizing the cycles such that the first cycle includes an intake stroke when the third cycle includes an outtake stroke, and the third cycle includes an intake stroke when the first cycle includes an outtake stroke.
37. The method of claim 34, further comprising synchronizing the cycles such that the first cycle includes an intake stroke while the second cycle includes an intake stroke.
38. The method of claim 37, further comprising synchronizing the cycles such that the third cycle includes an intake stroke while the second cycle includes an intake stroke.
39. The method of claim 38, wherein the fourth cycle includes an intake stroke while the third cycle includes an intake stroke.
40. The method of claim 33, wherein, when applying the voltage in the first cycle and the second cycle, an instantaneous flow rate of delivery fluid from the electrokinetic pump system never drops to zero.
41. The method of claim 33, wherein applying the voltage in the first cycle and the second cycle causes variations in an instantaneous flow rate of the delivery fluid from the electrokinetic pump system of less than 20% from a target flow rate.
42. The method of claim 41, wherein the instantaneous flow rate varies by less than 10%.
43. The method of claim 42, wherein the instantaneous flow rate varies by less than 5%.
Type: Application
Filed: May 7, 2012
Publication Date: Nov 8, 2012
Inventors: Kenneth Kei-ho Nip (Redwood City, CA), Kenneth R. Hencken (Pleasanton, CA), Doris Sun-Chia Shieh (Santa Clara, CA), Robert B. Lewis (Pleasanton, CA), Tuan Quoc Mai (San Ramon, CA)
Application Number: 13/465,927
International Classification: F04B 17/03 (20060101);