IFPAC 2003 Dr. Berthold Andres

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 Copyright 2002 ABB Automation - 4 -

Why use MEMS in Process Analytical? Copyright 2002 ABB Automation - 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

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,. Copyright 2002 ABB Automation - 7 -

1994: Our first introduction of a MEMS sensor Development of a Thermal Conductivity Detector (TCD) for gas analysis (e.g. Hydrogen in air, CO2 in air) Conventional design MEMS design 100 mm 10 mm Copyright 2002 ABB Automation - 8 - 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

Thermal Conductivity Analyzer, Summary Copyright 2002 ABB Automation - 9 - 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)

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 Copyright 2002 ABB Automation - 11 -

Micro Valve Array is required for Micro-GC Integration of multiple micro ball valves => Realization of dedicated flow schemes Copyright 2002 ABB Automation - 12 - Summary Micro ball valves can be produced But: Production of micro ball valve arrays is very complex, overall yield is too low

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 Copyright 2002 ABB Automation - 13 - Conventional design MEMS design 5 mm

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 Copyright 2002 ABB Automation - 14 - Current Micro FID has no substantial benefits compared to conventionally manufactured system

MEMS GC, Summary Copyright 2002 ABB Automation - 16 - 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

Next step: Concept for Micro-Mass-Spectrometer Target: MMS with the size of a cellular phone to driving electronics measurant acceleration electrode ionization chamber ions ion optics mass separator Copyright 2002 ABB Automation - 17 - Plasma Ion source acceleration grid noble gas e plasma to pump deflection electrodes to pump detector to detection electronics No UHV required! Separator with 1mm length

MEMS Mass-Spectrometer, Objectives Copyright 2002 ABB Automation - 18 - 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

MEMS Conclusions Copyright 2002 ABB Automation - 19 - 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