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Microelectromechanical Systems for Process AnalyticsIFPAC 2003

Dr. Berthold AndresABB Automation Products

Germany

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Process Analyzer and Instrumentation

Water analysisGas analysisPressure transmitterFlow transmitter

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Agenda

What are MicroelectromechanicalSystems (MEMS)

Why use MEMS technology for process analytical

ABB MEMS Projects

Summary

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What are Microelectromechanical System?Microelectromechanical System (MEMS) is a miniaturization technique based upon silicon wafer technology. This technology is a departure from the historical emphasis on the miniaturization of existing electrical, optical and mechanical assemblies

Examples

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Why use MEMS in Process Analytical?

Small is beautiful !!

5 mm

Size effects:Cost of manufacturing

Cost of Installation

Analyzer Location

Sampling systems

Shelters

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Why use MEMS in Process Analytical?

Manufactured in silicon wafer processes

Highly reproducible Lower manufacturing cost for larger quantities

Significantly smaller sizesLess consumables longer time of operationLower power demand

Portability Installation at the source

Faster response time possible Smaller dead volumeLower mass Shorter diffusion length

Designed as integrated assemblies

Further reduced size

Reduced number of components

Reduced integration time

Faster cycle time

Exchangeability of complete subassemblies

Maintenance is simplified

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Where to use MEMS in Process Analytical?

Two Types of MEMS ProjectsAnalyzer Components

Moderate Risk, High Reward

Detectors, Valves, columns, ionization chambers,….

Complete MEMS AnalyzersHigh Risk, High Reward

GC, MS, Titration,….

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1994: Our first introduction of a MEMS sensor

Conventionaldesign

MEMS design

100 mm 10 mm

Development of a Thermal Conductivity Detector (TCD) for gas analysis (e.g. Hydrogen in air, CO2 in air)

Designed as an integrated detector withThin-film measuring resistorThin-film reference resistorMembrane to control gas flow through detectorSize ~ 2 sq mmHousing and electronics are added in the next step

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Thermal Conductivity Analyzer, SummaryDevelopment was a big success Several thousands sold since introductionDrivers for success

Size of TCD detector can be minimized without loosing sensitivityBetter technical data because of smaller size

Smaller thermal capacity of detectorFaster response time

We already knew the application from our standard detectors“Simple” design of the detector. Housing and pneumaticalconnections are added in another production processMarket size is just large enough for the MEMS production

Current drawbackIt is difficult to control the production process for small quantities over a longer period of time (thousand is still a small number for a MEMS process)

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Realization of Micro GC with MEMS Components

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Micro-ValveTechnical Specifications

Micro ball valveElectromechanically activatedBall size ~ 500 µmPlasma etching to get high precision valve seatPressure range < 2 barPower consumption < 300 mW

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Micro Valve Array is required for Micro-GC

Integration of multiple micro ball valves

=> Realization of dedicated flow schemes

SummaryMicro ball valves can be produced

But: Production of micro ball valve arrays is very complex, overall yield is too low

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Micro Flame Ionization Detector for Micro-GC

Designed as an integrated detectorsilicon-glass technologyintegrated sample injection systemintegrated gold electrodesquartz capillary connectors

5 mm

MEMS designConventional design

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Flame Ionization Detector, Summary

Micro-FID has been built and is runningMicro-FID shows typical problem of MEMS technology that not everything can be simply scaled downQuenching distance between flame and electrodes does not allow to reduce size of flame substantially

Current Micro FID has no substantial benefits compared to conventionally manufactured system

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MEMS Thermal Conductivity Detector for Micro-GC

Fast Response Time< 10 ms

Low Detection Limit < 10 ppm

Advantages:• Small Thermal Capacity• Small Dead Volume

1 mm

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MEMS GC, Summary

Single components can be successfully designed

Complete GCVery complicate to go from prototypes to production

Each component must be developed and trouble shot as an individual

The integration of individual components is a second project and very complicated

GC Market Volumes are not compatible with MEMS

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Next step: Concept for Micro-Mass-Spectrometer

Target: MMS with the size of a cellular phone

plasmaacceleration grid

massseparator

to pump to pump

deflectionelectrodes

to detectionelectronics

detector

to drivingelectronics

ionoptics

ions

e

ionizationchamber

noblegas

measurant

acceleration electrode

Separator with1mm lengthPlasma

Ion source

No UHV required !

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MEMS Mass-Spectrometer, Objectives

Measuring principle or component must be scalable

ok for MSConcentrate on crucial parts of the system design where the MEMS technology can show all its advantages

e.g. mass separatorYield for MEMS processes, especially for difficult structures, is not always 100 %

MEMS should be split to several components which can be tested individually

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MEMS Conclusions

ABB has been successful at targeting analyzer components for the conversion to MEMS technology

Success comes from the use of MEMS components in conventional or miniature systems

Total integrated MEMS systems may require too much time to get out of the lab and become a real product