Microfluidic devices like channels, pumps and valves are basic components of micro gas analyzing systems. The project goal is the design, the fabrication and the characterisation of a novel micro gas injector for microanalysis systems in glass-silicon-glass microtechnology.

A moving microstructured slider with buried microchannels builds the base of the microinjector. The slider connects the inducting channels for sample and carrier gas to the conducting channels for injecting in a gas analysis system and exhaust gas channels respectively. By varying the channel length on the slider, e.g. in loop or meander shape, the volume of the injected sample gas can be adjusted to the respective gas analysis system. The figure shows the design of a microstructured gas injection system in principle.

The moving slider is fabricated by an anisotropic Bosch etch process. The top and bottom cover of the injection system are wet chemically structured glass substrates. For a gas tight and mechanical stabile connection these covers are anodically boned to the silicon substrate.

The buried microchannels are fabricated by a sequence of anisotropic and isotropic dry etching of the silicon substrate and subsequently closure of the microchannels by chemical vapour deposition.

For channel gap sealing and minimization of friction at slider motion by plasma polymerization conform deposited PTFE-layers are used. The plasma polymerized layers ensure an adequate leak thightness and they have no memory effect due to their high cross linking.

In addition to the commonly used MEMS actuation principles two novel drives for slider actuation shall be investigated: a pneumatic actuation with integrated membrane valves as well as a symmetric bi-metal actuator with silicon spring structures as reset device.

Such a gas injection system shall be used at a miniaturized gas chromatography system, mass spectrometry system, flame ionisation detector or spectrometry system.

Contact:

Dipl.-Ing. Holger Feindt

Funding:

Deutsche Forschungsgemeinschaft (DFG)

Publications:

• M. Doms, H. Feindt, A.S. Matar, D. Shewtanasoontorn, S. Brinkhues, J. Müller, Investigation of Different Hydrophobic Coatings For MEMS Applications, ICMAT 2007, International Conference on Materials for Advanced Technologies 2007, Singapore
• H. Feindt, A.Åž. Çubukçu, J. Müller, Elektrostatisch angetriebenes Silizium-Membranventil für Gasanalysesysteme, Mikrosystemtechnik Kongress 2007, Dresden
• M. Doms, H. Feindt, W.J. Kuipers, D. Shewtanasoontorn, A.S. Matar, S. Brinkhues, R.H. Welton, J. Müller, Hydrophobic Coatings for MEMS Applications, Journal of Micromechanics Microengineering Vol.18 (JMM), Issue 5, May 2008
• H. Feindt, S. Bohne, A.Reinert, J.Meurer, J. Müller, Herstellung von vergrabenen Kanälen für einen Mikrogasinjektor, demnächst veröffentlicht beim Mikrosystemtechnik Kongress 2009, Berlin