1,721,009 research outputs found
Silicon Micromachined Device Testing by Infrared Low-Coherence Reflectometry
No full textWith the development of silicon micromachining technologies, non-contact measurement techniques for in-depth non-destructive inspection of layered and microstructured samples are becoming increasingly relevant. In this paper, we apply optical low-coherence reflectometry (OLCR) to detect the optical path between the interfaces of several silicon devices with characteristic distance in the range 3–17 μm. The implemented configuration is based on a fiberoptic Michelson interferometer that exploits infrared broadband radiation in the wavelength range of 1.2–1.7 μm, with coherence length shorter than 2 μm, for performing spot tomographic measurements. OLCR enabled out-of-plane measurements on a MEMS linear accelerometer and in-plane measurements on vertical periodic silicon/air microstructures. The optical distance between hidden interfaces was found well in agreement with the design parameters
Characterization of rectangular glass micro-capillaries by low-coherence reflectometry
Full text linkWe report the functionality of optical low-coherence reflectometry (OLCR) to characterize glass micro-capillaries with 50-μm deep rectangular cross section, in view of their application as microoptofluidic devices. We exploited infrared radiation generated by a tungsten lamp in a time-domain low-coherence interferometer based on a fiberoptic Michelson scheme. OLCR allowed us to easily detect the optical distance between in-depth interfaces of the capillary as well as the refractive index of ethylene glycol solutions in water at different concentrations, which were inserted into the channel by capillary action
Infrared structured light generation by optical MEMS and application to depth perception
No full textThree-dimensional imaging solutions provide depth perception that cannot be achieved with traditional two-dimensional systems. A 3D optical inspection system can be implemented using structured light as 3D sensing technology. In this paper, we show that structured light can be projected onto the measured object by means of an innovative scanning microsystem that employs a single-axis torsional MEMS mirror for fast steering a near infra-red laser beam on a diffractive silicon microstructure. As a proof of principle of the functionality of the designed microsystem, the generated line patterns are shone on 3D objects and deformation of the projected lines is detected with a CMOS camera. From line deformation, the object depth is calculated and found in accordance to the geometrical size. The developed miniaturized solution overcomes typical drawbacks of other scanning technologies such as large size and heavy weight
An innovative cell microincubator for drug discovery based on 3D silicon structures
Full text linkWe recently employed three-dimensional (3D) silicon microstructures (SMSs) consisting in arrays of 3 m-thick silicon walls separated by 50 m-deep, 5 m-wide gaps, as microincubators for monitoring the biomechanical properties of tumor cells. They were here applied to investigate the in vitro behavior of HT1080 human fibrosarcoma cells driven to apoptosis by the chemotherapeutic drug Bleomycin. Our results, obtained by fluorescence microscopy, demonstrated that HT1080 cells exhibited a great ability to colonize the narrow gaps. Remarkably, HT1080 cells grown on 3D-SMS, when treated with the DNA damaging agent Bleomycin under conditions leading to apoptosis, tended to shrink, reducing their volume and mimicking the normal behavior of apoptotic cells, and were prone to leave the gaps. Finally, we performed label-free detection of cells adherent to the vertical silicon wall, inside the gap of 3D-SMS, by exploiting optical low coherence reflectometry using infrared, low power radiation. This kind of approach may become a new tool for increasing automation in the drug discovery area. Our results open new perspectives in view of future applications of the 3D-SMS as the core element of a lab-on-a-chip suitable for screening the effect of new molecules potentially able to kill tumor cells
Recognition of human cells in a glass-silicon Fabry-Perot microcavity by spectral reflectivity measurements
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Optical detection of the electro-mechanical response of MEMS micromirrors designed for scanning picoprojectors
Full text linkSingle-axis, rotational micromirrors actuated by comb finger structures have been designed, in view of their application in reflective scanning picoprojectors for laser beam displacement along two perpendicular directions to obtain a raster scan scheme. A resonant mirror operating at a frequency around 25 kHz, suitable for horizontal scans, as well as a linear mirror, suitable for vertical scan at the typical video refresh rate (60 Hz), have been fabricated by Silicon-on-Insulator technology and are illustrated in this work. We have in particular exploited the potentialities of semiconductor laser self-mixing interferometry, a powerful technique for characterizing the dynamic response of MEMS, for detecting the electro-mechanical response of both kinds of micromirrors. We report the results of the spot optical measurements performed on resonant and linear mirrors aimed at detecting the frequency of the fundamental rotational mode as well as of the in-plane and out-of-plane modes, close in frequency to the fundamental mode. We have experimentally demonstrated that the fabricated devices are suitable for high resolution miniaturized projectors, in terms of frequency response and scanning angle
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