07/25/2018

Versatile optical multi-sensor technology in the production of microfluidic systems

 

There are many different optical measurement techniques available today, each with its own specific field of application. Where infrared light emitting chromatic sensors are mainly used for layer thickness measurements, chromatic white light sensors are used for fast and accurate measurements of profile, topography and roughness on samples up to 1000 mm × 1000 mm. The x,y resolution of these sensors varies between 1.8 μm and 12 μm. The measuring range is usually between 100 μm and 10 mm and provides a maximum vertical resolution of 3 nm to 100 nm.

An application example of a FRT multi-sensor configuration is the measurement of laser-welded contours in MEMS production.

When it comes to MEMS devices such as microfluidic systems, laser welding is a possible solution for assembly. Laser welding technology produces both fluid and airtight seams. The advantages of laser welding are its high speed, precision and repeatability, making it an ideal technology for inline production. Laser welding in the field of MEMS works according to the principle of light absorption.

Two polymer layers, one opaque (foil), the other translucent (component to be covered with foil), are placed on top of each other. A laser beam enters through the transparent layer and hits the light absorbing (upper) layer. The photons of the laser are absorbed by the opaque layer, which generates just enough thermal energy to precisely fuse the two polymers at a specific point. This enables seam widths of approx. 200 μm in width. The film is lifted between these seams. The difference in height is very interesting information for R&D and production quality.

For this application our (automated) multi-sensor measuring tools of the MicroProf® series can be used. Thanks to their modular concept, our measuring tools combine the strengths of several different measuring methods in a fully integrated measuring system. In such a scenario, a high-resolution chromatic point sensor measures profiles, topography or the roughness of the seam widths of the components. A film thickness sensor can be installed to measure the thickness of the top layer. An AFM or confocal microscope is used for high-resolution magnifications of selected areas of the component. The main advantages of our multi-sensor measuring tools are their adaptability, reduced space requirements, future-proof and cost-efficient operation.

By adding the thermo unit to the MicroProf® you can use our optical sensors to measure the surface topography of your microfluidic systems under controlled thermal stress. Both fully automatic measurements of the surface topography at different temperatures and dwell times at constant temperatures are completely adjustable. The thermo unit is available as an extension for all FRT instruments and is mounted as a separate module like a normal sample holder.

Whether laboratory, development, quality assurance or production - FRT offers the suitable measurement technology for your MEMS application. Do not hesitate to contact us if you have any questions. Our experts will be glad to help you solve your measurement tasks by creating the best possible system configuration for you. In our opinion, a comprehensive solution consists not only of hardware and software development, but also of supplementary services and effective technical customer service. FRT provides on-site support through a global network of subsidiaries and distributors. FRT Remote Support enables our experts to support customers worldwide.