MEMS - the smallest dimensions, the highest precision.
The individual components of microsystems cannot be detected with the naked eye. Parts like switches and gears are smaller than a grain of sand. However, despite this small size "micro-electrical-mechanical systems" (MEMS) offer many advantages compared to conventional macrosystems.
What makes MEMS special?
Many products including their functions are only possible thanks to the utilisation of MEMS. This is because they aren't affected by the problems that affect other systems, like fine mechanical systems for instance: wear, inertia and sensitivity to vibration are avoided completely. Furthermore, their manufacturing is predestined to revolutionise mass markets. Although microelectronics processes are required for the production, the quantity of resources being utilised are considerably lower. Low production costs, low energy consumption and a robust design are all associated with the miniature construction size.
What does MEMS do in the scanning grating spectrometer?
MEMS - MEMS scanning grating - is at the heart of HiperScan's scanning grating spectrometer (SGS). Grating is similar to a lattice. Light can be bent thereby splitting its spectrum by using a grate of this kind - similar to a prism. In daily life, diffraction grating is used in CDs as well as in laser shows. In addition to the visual diffraction grating, the chip used in the SGS also contains a rotary axis as well as an electrostatic drive. This shifts the grating 150 times per second in exact vibration around its axis. The movement deflects the light's individual wave lengths where they can then be guided separately and in sequence into a detector to be measured. The physical principle applies here: the longer the waves of the light, the stronger the diffraction.
What exactly is the scanning grating spectrometer able to do thanks to MEMS?
MEMS scanning grating is the reason for many essential advantages:
- The diffraction grating in the MEMS-chip vibrates in resonance. A natural vibration of this kind is very precise, thus the wave length scale is very reproducible.
- The vibrating diffraction grating is produced with the precision of micrometers. Its virtually perfectly symmetrical structure helps in that the movements and vibrations of the spectrometer are not transferred to the grating vibration. In this way, the wave length scale remains stable.
- The temperature drift of the wave length scale is exceptionally low. This is because all the visual components are so small that they are held point by point and embedded in a visual bank made from massive aluminium. Temperature changes do not affect the angle of the beam path.
- The fine torsion springs, which form the axis of the vibrating diffraction grating, consist of monocrystalline silicon. This is why they remain absolutely free of wear, even after billions of vibrations.
- The monocrystalline torsion springs are only 5 micrometers wide, however they can hold over 2,500 diffraction gratings. This makes them very robust - even when exposed to hard impacts.
- Using MEMS, the entire spectrum can be measured with a single, selected detector. The resulting, consistent quality applies across the entire spectral range. In this way, the creation of transferable chemometric models that send the same results to all devices is simplified.
- Moreover, MEMS are very small. This is why the scanning grating spectrometer is small despite its performance power, and can even be perspectively tiny.