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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

5Introduction
Actuatorssuchaspumps,compressors,andvalvesareusedtoalterthestateofthefluidpressure,temperature,orflow
MicrofabricationtechniquescreatedforthesemiconductorintegratedcircuitindustryhavefoundnewapplicationsinMEMSresearch,developmentandmanufacture
Microvalvesareaprimarycomponentofmicrofluidicsystems
Actuatorsrelyonavarietyofactivationmechanism,suchaselectromagnetic, electrostatic,pneumatic,bimetallicalloys,shape-memoryalloys(SMA),electro- chemicalandthermopnematic
Distributionchannels,suchasorificesandmicrochannels,carrythefluidfromoneportionofthesystemtoanother

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

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

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

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

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

14Advantages
Increasedperformance
Higherlevelsoffunctionalintegration
HigherResolution
Decreasedsize
IncreasedreliabilityDisadvantages
Thepowerrequiredforactuation
Responsespeed
Theeffectofshrinkingsize
Structuralparameters
Choiceofthermopneumaticliquid

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

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

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Application of Micro fabricated valves based on the principles of thermo pneumatic actuation

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