© C

opyr

ight

200

2 A

BB

.A

ll rig

hts

rese

rved

. -

Microelectromechanical Systems for Process AnalyticsIFPAC 2003

Dr. Berthold AndresABB Automation Products

Germany

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 3

-

What are Microelectromechanical Systems (MEMS)

Why use MEMS technology for process analytical

ABB MEMS Projects

Summary

Agenda

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 4

-

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

What are Microelectromechanical System?

Examples

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 5

-

Why use MEMS in Process Analytical?

Size effects:

Cost of manufacturing

Cost of Installation

Analyzer Location

Sampling systems

Shelters

5 mm

Small is beautiful !!

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 6

-

Manufactured in silicon wafer processes Highly reproducible Lower manufacturing cost for

larger quantities

Significantly smaller sizes Less consumables longer

time of operation Lower power demand

Portability Installation at the source

Faster response time possible Smaller dead volume Lower 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

Why use MEMS in Process Analytical?

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 7

-

Where to use MEMS in Process Analytical?

Two Types of MEMS Projects Analyzer Components

Moderate Risk, High Reward

Detectors, Valves, columns, ionization chambers,….

Complete MEMS Analyzers High Risk, High Reward

GC, MS, Titration,….

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 8

-

1994: Our first introduction of a MEMS sensor

Designed as an integrated detector with Thin-film measuring resistor Thin-film reference resistor Membrane to control gas flow through detector Size ~ 2 sq mm Housing and electronics are added in the next step

Conventional

design

MEMS

design

100 mm 10 mm

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

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 9

-

Thermal Conductivity Analyzer, Summary

Development was a big success Several thousands sold since introduction

Drivers for success Size of TCD detector can be minimized without loosing

sensitivity Better technical data because of smaller size

Smaller thermal capacity of detector Faster response time

We already knew the application from our standard detectors

“Simple” design of the detector. Housing and pneumatical connections are added in another production process

Market size is just large enough for the MEMS production

Current drawback It 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)

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 1

0 -

Realization of Micro GC with MEMS Components

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 1

1 -

Micro-Valve Technical Specifications

Micro ball valve Electromechanically activated Ball size ~ 500 µm Plasma etching to get high precision valve seat Pressure range < 2 bar Power consumption < 300 mW

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 1

2 -

Micro Valve Array is required for Micro-GC

Integration of multiple micro ball valves

=> Realization of dedicated flow schemes

Summary Micro ball valves can be produced

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

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 1

3 -

Micro Flame Ionization Detector for Micro-GC

Designed as an integrated detector silicon-glass technology integrated sample injection system integrated gold electrodes quartz capillary connectors

MEMS designConventional design

5 mm

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 1

4 -

Flame Ionization Detector, Summary

Micro-FID has been built and is running Micro-FID shows typical problem of MEMS

technology that not everything can be simply scaled down

Quenching 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

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 1

5 -

MEMS Thermal Conductivity Detector for Micro-GC

Fast Response Time < 10 msLow Detection Limit < 10 ppm

Advantages:

• Small Thermal Capacity• Small Dead Volume

1 mm

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 1

6 -

MEMS GC, Summary

Single components can be successfully designed

Complete GC Very 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

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 1

7 -

Next step: Concept for Micro-Mass-Spectrometer

plasm a

acceleration grid

m assseparator

to pum p to pum p

deflectionelectrodes

to detectionelectron ics

detector

to drivingelectron ics

ionoptics

ions

e

ionizationcham ber

noblegas

m easurant

acceleration e lectrode

Target: MMS with the size of a cellular phone

Plasma Ion source

Separator with1mm length

No UHV required !

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 1

8 -

MEMS Mass-Spectrometer, Objectives

Measuring principle or component must be scalable ok for MS

Concentrate on crucial parts of the system design where the MEMS technology can show all its advantages e.g. mass separator

Yield for MEMS processes, especially for difficult structures, is not always 100 % MEMS should be split to several components which can be tested individually

© C

opyr

ight

200

2 A

BB

Aut

omat

ion

- 1

9 -

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