Bringing NIR spectrometers into mobile phones

Next generations of mobile phones will contain spectral analysers. Different concepts and system designs compete in this ultra-high volume market. Especially for the analysis of organic matter, which can be food, human skin or other items, the near infrared range offers substantial advantages, most of all a suitable penetration depth and relevant spectral information. On the other hand the spectrometer has to meet the requirements for the use in a mobile phone, i.e. size and price must drop significantly. The reliable operation, especially for the evaluation of the spectra with chemometric models, requires a very stable wavelength scale of the spectroscopic system. The deviation must not exceed 0.5 nm during operation under any condition and for each device used. Resonant MEMS devices combine multiple advantages: Ultra compact designs can be realized, MEMS motions allow an operation using a single detector to meet cost issues even with extended InGaAs technology and the position feedback ensures a precise and long term stable wavelength scale. Based on such resonantly actuated MEMS components NIR spectrometers have been designed. Recent research work aims for extreme miniaturization of the optical bench. The presented assembly technology has been optimized for volume production. The outline from the previous published work will be shrunk to 10 x 10 x 5 mm3 with only a slightly reduced resolution. The new design will be optimized for cost efficient production as well.