Pint-sized spectrometers harness MEMS

Fraunhofer Gesellschaft has 67 institutes spread across Germany each specializing in a different kind of applied technology employing in total of 23,000 scientists and engineers with a research budget of approximately $2 billion, 30 percent of which comes from the government and 70 percent comes from contracts with industry.

The pint-sized MEMS-based spectrometers it was showing came in two sizes–small and tiny. The larger model, about the third the size of a shoebox (compared with laboratory spectrometers the size of a suitcase) uses MEMS optical inference filters to cover a wide range of wavelengths–from 3-to-11 microns wavelength–using silicon wafer processing. The full width / half maximum (FWHW) bandwidth reached down to the nano-scale 50-to-200 nanometers, depending on the interference order used.

The complete detector module for this tiny MEMS spectrometer fits in a TO-8 housing.
(Source: Fraunhofer, used with permission.)

The electrically tunable pass band had a maximum transmittance of more than 70 percent using two equal and movable reflector carriers, which minimized vibration and gravitation induced forces on the reflector spacing keeping the center of the passband rock solid.

The smallest current chip size of the Fabry-Pérot interferometer (FPI) is 7x7x0.6mm.
(Source: Fraunhofer, used with permission)

The larger spectrometer can replace laboratory spectrometers that do not need the highest possible sensitivity or spectral range and are a perfect replacement for application specific spectrometers. Other applications include industrial process spectrometers, control of biogas plants, fuel monitoring systems and food quality analysis.

The administrative center of the multi-building Fraunhofer Institutes’s Electronic Nano Systems (ENAS) operation in Chemnitz, Germay. (Source: Fraunhofer, used with permission)

The smaller spectrometer is based on a Fabry-Pérot interferometer (FPI) that can be fabricated small enough to fit in a TO-8 housing. The FPI on-a-chip measures 7-by-7-by-0.6 millimeters and is intended to extend the functionality of standard fixed wavelength multi-color infrared detectors.

Their extreme low price and small size makes them suitable for large volume applications of infrared spectroscopy including spectral imaging, medical measurements, industrial gas analyzers, attenuated total reflection (ATR) sensors in chemical plants, handheld analyzes, sensor networks, warning and safety systems.