A review of visible-range Fabry–Perot microspectrometers in silicon for the industry

This review presents microspectrometers in silicon for the industry for measuring light in the visible range, using the Fabry–Perot interferometric technique. The microspectrometers are devices able to do the analysis of the individual spectral components in a given signal and are extensively used on spectroscopy. The analysis of the interaction between the matter and the radiated energy can found huge applications in the industrial sector. The microspectrometers can be divided on three types, determined by the dispersion element or the used approach and can be found microspectrometers based on prisms, gratings interferometers. Both types of microspectrometers can be used to analyze the spectral content ranging from the ultraviolet (UV, below 390 nm), passing into the visible region of the electromagnetic spectrum (VIS, 390–760 nm) up to the infrared (IR, above 760 nm). The microspectrometers in silicon are versatile microinstruments because silicon-compatible techniques can be used to assembly both the optical components with the readout and control electronics, thus resulting high-volume with high-reproducibility and low-cost batch fabrications. A compensation technique for minimizing the scattered light effects on interferometers was implemented and is also a contribution of this paper. Fabry–Perot microspectrometers for the visible range are discussed in depth for use in industrial applications.     

The discretized flow on domains of attraction: a structural stability result

It is well known that, for stepsize sufficiently small, compactattractors of ordinary differential equations persist underdiscretization. The present paper describes the structure ofthe discrete-time dynamical system obtained via discretizationon A(M_h)\M_h where M_h is the approximate attractor and A(M_h)is its domain of attraction. The existence of a smooth embeddinginto a continuous-time parallelizable flow is proved. The constructioncan be used to define sections for discretizations and can beinterpreted as a justification of the method of modified equations.     

A lab-on-a-chip for spectrophotometric analysis of biological fluids

This paper reports a lab-on-a-chip for application in clinical analysis, especially in the spectrophotometric analysis of biological fluids. It is composed of three parts: (1) a microfluidic system die containing the microchannels fabricated using SU-8 techniques; (2) an optical filtering system based on highly selective Fabry-Perot optical resonators using a stack of CMOS process compatible thin-film layers; (3) a detection and readout system fabricated in a CMOS microelectronic process. The system enables low-cost and selective measurement of the concentration of several biomolecules in biological fluids. Operation is based on optical absorption in a well-defined part of the visible spectrum, defined by the reaction of a specific reagent with a specific biomolecule. Signals proportional to the intensity of the light transmitted through the biological fluid are available at the output in the form of bit streams, which allows simple computer interfacing. Moreover, the optical filtering system enables the measurement using white light illumination, thus avoiding the use of a wavelength dependent light source. This characteristic makes the lab-on-a-chip portable and ensures that the analysis can be performed at any location with instantaneous results, without the use of complex and expensive analysis systems. The quantitative measurement of uric acid and total protein in urine is demonstrated.