In this work, we present two micro-opto-fluidic platforms for smart recognition of water-based fluids exploiting absorption spectroscopy. The identification of the samples is based on their absorption properties in the near infrared region from 1165 nm to 1650 nm and, in particular, on the analysis of the absorption band of water located around 1450 nm. In the instrumental setup, the fiber-coupled light emitted by a Tungsten lamp is shone onto the micro-devices and the output radiation is directed to an optical spectrum analyzer. The first platform works in reflection by means of a rectangular glass micro-capillary with integrated reflectors. Thanks to the presence of the double metallization, light can cross the capillary channel multiple times in order to enhance measurement sensitivity. The second platform works in transmission and exploits a commercial device with a micro-fluidic polymeric channel. The performances of the sensing platforms were initially theoretically studied by implementing a MATLAB® model based on geometrical optics and Lambert-Beer formula for absorption. Then, experiments were carried out by testing wateralcohol dilutions, proving results in a good level of agreement with the theoretical predictions. We also successfully employed our platforms for specific measurement of the water content in Scottish whisky and Venezuelan white rum liquor. The proposed readout technique is remote, contactless, non-invasive, and thus totally safe. Moreover, borosilicate glass micro-capillary and polymeric channel are both sterile, biocompatible and low-cost devices. These features make our opto-fluidic-platforms highly suitable also for many other applications, ranging from biology to food analysis.
In this work, we reconsider optical transillumination for in vivo tissue imaging and for detection of time-dependent vital signs. Two portable optoelectronic instrumental configurations have been assembled and tested to achieve efficient transillumination and image detection of the inner structure of diffusing non-homogeneous biological samples with thickness of a few centimeters, with a resolution sufficient for differentiating internal macroscopic tissue structures. Tissue illumination is obtained with an extended source consisting in a matrix of Near Infra-Red (NIR) light emitters. To demonstrate the potentiality of this system for generating low resolution images of in vivo human tissues, it has been employed for transilluminating human upper limbs. Images featuring good contrast are acquired non-invasively with a monochrome CMOS camera turned into a wavelength selective image detector using optical filters. The collected images of human hands provide a clear visualization of the hand dorsal vein pattern. From recorded videos, we extract a timevarying signal that closely resembles the blood pressure wave: in its spectral content we recognize the frequency components corresponding to the expected heart and breath rates.
The successive ion layer deposition reaction (SILAR) technique has been applied to CdSe based systems to develop
Type 1 heterostructures . In such structures, the CdSe core is covered by wider band gap semicondutors to improve the
emission properties. Cores of different dimensions has been synthesised and two different shell structures have been
addressed.
The obtained particles have been characterised by TEM technique, while UV-Vis absorption and photoemission
spectroscopy were used to characterise the optical properties of the particles in the colloidal solution.
The obtained particles were also introduced in a ZrO2 sol-gel matrix to fabricate photoluminescent waveguides, which
were characterised also by spectroscopic ellipsometry.
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