Application of Micro fabricated valves based on the principles of thermo pneumatic actuation
1. M. S. Ramaiah School of Advanced Studies
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M. Sc. (Engg.) in Electronics System Design Engineering
GREESHMA S
CWB0913004 , FT-2013
4thModule Presentation
Module code : ESE2513Module name : Low Voltage ElectronicsModule leader: Ms. Nireeksha/ Ms. Malathi Presentation on : 14/02/2014
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Application of Micro fabricated valves based on the principles of thermo pneumatic actuation
Presentation on
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•ABSTRACT
•INTRODUCTION
•THERMOPNEUMATICMICROVALVETECHNOLOGY
•REFRIGERATIONAPPLICATION
•SEMICONDUCTORPROCESSAPPLICATION
•MASSFLOWMEASUREMENTPRINCIPLE
•ADVANTAGES
•DISADVANTAGES
•CONCLUSION
•REFERENCES
Overview
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Abstract
Intermsofcontrolanddistributionofliquidsandgases(microfluidics),MEMS- baseddevicesoffersopportunitiestoachieveincreasedperformanceandhigherlevelsoffunctionalintegration,atlowercost,withdecreasedsizeandincreasedreliability
Microfluidicactuatorsincludedistributionmicrochannelsandorifices,microvalves, micropumps,andmicrocompressors
Relatedmicrosensorsarerequiredtomeasuretemperature,flow,pressure, viscosity,anddensity
Abriefcomparisontootheractuationtechniquesismade,scienceandtechnologyofsilicon-basedthermopneumaticmicrovalves
Expansionvalvesforrefrigerationcontrol
5. M. S. Ramaiah School of Advanced Studies
5Introduction
Actuatorssuchaspumps,compressors,andvalvesareusedtoalterthestateofthefluidpressure,temperature,orflow
MicrofabricationtechniquescreatedforthesemiconductorintegratedcircuitindustryhavefoundnewapplicationsinMEMSresearch,developmentandmanufacture
Microvalvesareaprimarycomponentofmicrofluidicsystems
Actuatorsrelyonavarietyofactivationmechanism,suchaselectromagnetic, electrostatic,pneumatic,bimetallicalloys,shape-memoryalloys(SMA),electro- chemicalandthermopnematic
Distributionchannels,suchasorificesandmicrochannels,carrythefluidfromoneportionofthesystemtoanother
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6Thermopneumatic Microvalve TechnologyFigure1CrosssectionofaThermopneumaticallyActuatedMicrovalve
Figure2DrillholesinPyrex
Waferultrasonically
Figure3MetalizePyrexwafer
Figure4DefinemembraneLithographically(goldoxides, Photo-resistmasks) Figure5EtchmembranewaferinKOH;stripmaskingmaterialsFigure6Defineorificewaferlithographically
Figure7Etchorificewaferin
KOH
Figure8Fabricationsequencefora
normallyopen,thermopneumatic
valves
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Thermopneumatic Microvalve Technology
Figure 9 Estimated flow based on loss coefficient
flow measurements
Figure 10 Relationship between the equilibrium membrane to inlet Figure 11 Predicted effect of scaling on microvalve responsetime
8. M. S. Ramaiah School of Advanced Studies
8Refrigeration Application
Normally-open microvalves have been applied to the problem of controlling liquid flow
Refrigerant liquids present unusual challenges for thermally activated microvalves
The pressure versus flow versus valve power input for one such microvalve is shown
Figure 12 Pressure vs. R-13a flow vs. pressure
for a representative microvalve
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Semiconductor process Applications
The present and future requirements of the semiconductor industry for gas distribution and control
The thermopnematic actuation principle is employedFigure 13 Cross section of thermo pneumaticallyactuated , normally closed, low leakage shut offvalve
The silicon-ceramic interface is a eutectic bond
The overall dimension are 8mm X 6mm X 2mm, and are roughly scale
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10Mass flow Measurement principleFigure 14 Schematic of O-ring used in the vacuum ring rate shutoff valve
Figure 15 Helium leak rate for vacuum leak-rate for
Microvalves
Figure 16 Schematic representation of the low-
flow MFC
Figure 17 Pressure Sensor Resolution Required to achieve a given flow resolution, as a Function of criticalorifice Hydraulic Diameter
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11Mass flow Measurement principleFigure 18 Schematic representation of the compressible flow model for the series combination of normally-open proportional valve, and a critical orifice. Figure 19 Measured Flow Characteristics for a Low-FlowMFCFigure 20 Measured flow from a 10 sccm Mass- flow controller
Figure 21 Measurement precision results from a 10 sccm
mass-flow controller
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Mass flow Measurement principleFigure 22 Measurement reproducibility results from a 10 sccm Mass-Flow controllerFigure 23 Flow model for the MFC Figure 24 Example Isometric View of a Pressureregulator, MFC, or shut-off valve. Figure 25 Isometric View of a 4-Channel Gas stick
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13Mass flow Measurement principle
Figure 26 Schematic of One Channel of an
Integrated Gas Stick
Figure 27 Size Comparison of Resent and Future Integrated Gas
Sticks/panels
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14Advantages
Increasedperformance
Higherlevelsoffunctionalintegration
HigherResolution
Decreasedsize
IncreasedreliabilityDisadvantages
Thepowerrequiredforactuation
Responsespeed
Theeffectofshrinkingsize
Structuralparameters
Choiceofthermopneumaticliquid
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15Conclusion
The science and technology required to design and fabricate flow distribution and control devices suitable for semiconductor processing industry
Components such as pressure-based flow models, critical orifices, pressure temperature sensors normally-closed vacuum leak rate shut off valves, have developed
These components are combined at higher level into integrated gas panels which has benefit of smaller size, lower cost, higher resolution , materials compatibility and lower defect generation which are among the attributes of the successful application of MEMS-based technology
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16References
Elisabeth verpoorte and nicof.de.rooij,fellow, (2003). Microfluidics Meets MEMS. 6th ed. Switzerland: University of Neuchâtel. 930-953
Albert K. Henning (1998).Microfluidic MEMS. CA: -. 471-486