Search results for " Silicon"
showing 10 items of 247 documents
Fluorescent Biosensors Based on Silicon Nanowires
2021
Nanostructures are arising as novel biosensing platforms promising to surpass current performance in terms of sensitivity, selectivity, and affordability of standard approaches. However, for several nanosensors, the material and synthesis used make the industrial transfer of such technologies complex. Silicon nanowires (NWs) are compatible with Si-based flat architecture fabrication and arise as a hopeful solution to couple their interesting physical properties and surface-to-volume ratio to an easy commercial transfer. Among all the transduction methods, fluorescent probes and sensors emerge as some of the most used approaches thanks to their easy data interpretation, measure affordability…
Functional Near Infrared Spectroscopy System Validation for Simultaneous EEG-FNIRS Measurements
2019
Functional near-infrared spectroscopy (fNIRS) applied to brain monitoring has been gaining increasing relevance in the last years due to its not invasive nature and the capability to work in combination with other well–known techniques such as the EEG. The possible use cases span from neural-rehabilitation to early diagnosis of some neural diseases. In this work a wireline FPGA–based fNIRS system, that use SiPM sensors and dual-wavelength LED sources, has been designed and validated to work with a commercial EEG machine without reciprocal interference.
A diagnostic trap for the dermatopathologist: granulomatous reactions from cutaneous microimplants for cosmetic purposes.
2007
We present a case of late granulomatous reactions from silicone that first appeared in a site different from that of the injection causing an incorrect diagnosis of liposarcoma in the beginning. The histological picture was a cystic-macrophagic granuloma in both the injection site (upper lip) and the migrating site (paranasal regions). We think that the foreign body has undergone an antigravity migration from the upper lip to the right paranasal region. To our knowledge, such a phenomenon has not been yet reported in literature.
"Doctor, tengo un bulto en la axila". Adenomegalia siliconomatosa postmamoplastia de aumento: a propósito de ocho casos
2010
La aparición de adenopatías axilares asociadas a mamoplastia de aumento mediante prótesis de silicona es un hecho infrecuente, no excepcional, y muy preocupante para paciente y cirujano. Hemos hecho una revisión de 1697 historias clínicas de pacientes sometidas a mamoplastia de aumento mediante prótesis de silicona al objeto de estudiar la relación entre roturas protésicas y adenopatías axilares Las 1697 pacientes se dividieron en grupos que cumplían 1, 2, 3, 5 y 7 años de haber sido intervenidas. Revisamos sus historias clínicas y estudiamos las que con posterioridad a la cirugía habían consultado por sospecha de rotura protésica y adenopatías axilares. No encontramos roturas protésicas an…
The effect of immersion disinfection procedures on dimensional stability of two elastomeric impression materials
2008
The aim of this study was to determine the effect of immersion disinfection procedures on the dimensional stability of two elastomeric impression materials. Impressions of a stainless steel die were made with polyether (PE) and with additionpolymerized silicone rubber (PVS). The test specimens underwent disinfection treatment by immersion in two commercially available solutions containing quaternary ammonium compounds (Sterigum Powder, SP) and glutaraldehyde plus an amino derivative (MD520, MD), respectively. The impressions were measured at 4 different time points: before any disinfection treatment (T0); after the first disinfection (T1); 6 hours after the first disinfection (T2); after th…
Calibration of the underground muon detector of the Pierre Auger Observatory
2021
To obtain direct measurements of the muon content of extensive air showers with energy above $10^{16.5}$ eV, the Pierre Auger Observatory is currently being equipped with an underground muon detector (UMD), consisting of 219 10 $\mathrm{m^2}$-modules, each segmented into 64 scintillators coupled to silicon photomultipliers (SiPMs). Direct access to the shower muon content allows for the study of both of the composition of primary cosmic rays and of high-energy hadronic interactions in the forward direction. As the muon density can vary between tens of muons per m$^2$ close to the intersection of the shower axis with the ground to much less than one per m$^2$ when far away, the necessary bro…
Purification of Nano-Porous Silicon for Biomedical Applications
2011
Recently, various bio-medical applications of nanoporous silicon (np-Si) have been suggested. This work investigates the biocompatibility of np-Si particles taking into account hazardous residua confined in the pores after preparation. The emphasis is on the potential application of such particles as oxygen photosensitizer for photodynamic therapy of cancer, which requires both negligible toxicity of np-Si particles in darkness and a high photo-cyto-toxic effect due to generation of singlet oxygen under illumination. Considerable amounts of water soluble toxic impurities are found to be present in the nanoporous shell of micrometer-sized np-Si particles immediately after their preparation b…
Refractive index sensing by a silicon metasurface
2022
The availability of smart materials represents a key enabling milestone for the realization of smart sensors. In this research field, optical sensing has gained a lot of attention in various applications ranging from basic physics to chemistry and biology. Here, we exploit the non-invasive nature of light to achieve an innovative sensor based on all-optical dielectric nano-resonators arranged in a periodic fashion. The proposed sensor can measure refractive index changes up to 10(-6).
Signal to noise ratio measurements of silicon photomultipliers
2014
We report on our signal to noise ratio (SNR) measurements carried out, in the continuous wave regime, on a novel class of silicon photomultipliers (SiPMs) fabricated in planar technology on silicon p-type substrate. SiPMs are large area detectors consisting of a parallel array of Geiger Mode APDs with individual integrated quenching resistors. Each photodiode is an independent photon counting microcell and is connected to a common analog output to produce a summation signal proportional to the number of detected photons [1], [2]. SNR of SiPMs is expressed by the ratio of the SiPM average signal current and the RMS deviation of the overall current (i.e., the overall shot noise current). The …
Single Event Burnout of SiC Junction Barrier Schottky Diode High-Voltage Power Devices
2018
Ion-induced degradation and catastrophic failures in high-voltage SiC Junction Barrier Schottky (JBS) power diodes are investigated. Experimental results agree with earlier data showing discrete jumps in leakage current for individual ions, and show that the boundary between leakage current degradation and a single-event-burnout-like effect is a strong function of LET and reverse bias. TCAD simulations show high localized electric fields under the Schottky junction, and high temperatures generated directly under the Schottky contact, consistent with the hypothesis that the ion energy causes eutectic-like intermixture at the metal- semiconductor interface or localized melting of the silicon …