1,721,001 research outputs found
A VERSATILE ROUTE FOR THE FABRICATION OF SILICON MICRONEEDLES FOR TRANSDERMAL APPLICATIONS BY ELECTROCHEMICAL MICROMACHINING TECHNOLOGY
No full textIn this work, we report a novel, versatile, and low-cost approach for the fabrication of both “flat” and “sharp” out-of-plane silicon microneedles for transdermal applications. Unlike state-of-the-art microneedles reported so far, the microneedles of this work feature a built-in reservoir in the needle-core to be used for drug storing and deliv-ery after insertion in the skin. The microneedles, with height of about 100 μm and density between 625 needles/cm2 (spatial period of 400 μm) and 40000 needles/cm2 (spatial period of 50 μm), are effectively fabri-cated by silicon electrochemical micromachining technology. In-vitro insertion tests carried out on both synthetic and hairless-mouse skins clearly demonstrate penetration efficacy and reliability of such tiny needles, which are up to ten times thinner than a human hair
COMPOSITE SILICON/METAL NANOSTRUCTURES BY METAL-ASSISTED ETCHING FOR CHEMI-TRANSISTOR SENSORS
No full textThis work reports on the use of composite silicon/metal nanostructures (cSiMN) prepared by Metal Assisted Etch-ing (MAE) as highly sensitive material for the fabrication of chemi-transistor gas sensors operating at room tem-perature. As a case-of-study, we investigate the integration of composite silicon/gold nanostructures (cSiAuN) synthesized by MAE in solid-state transistors, namely junction-field-effect transistors (JFET), aimed at the detec-tion of nitrogen dioxide (NO2) down to 100-part-per-billion (ppb). The resulting chemi-transistor sensor, namely cSiAuJFET (Composite Silicon Gold JFET), consists of a p-channel JFET in which the cSiAuN layer is placed on top of the p-channel and acts as a sensing gate. A thorough electrical characterization, both static and dynamic, of the cSiAuJFET sensor is performed in NO2 at concentration of hundreds ppb using synthetic air as carrier gas. Notably, the cSiAuJFET sensors show fast and reliable response to NO2 in the range 100-500 ppb without signifi-cant aging effects, in terms of response times and sensitivity value, up to a few days of continuous operation
Microsistema optofluidico a cristalli fotonici e procedimento di realizzazione dello stesso
No full textHIGH-ASPECT-RATIO PHOTONIC CRYSTALS FOR CAPILLARY OPTOFLUIDICS: TOWARDS DROP-AND-MEASURE PLATFORMS
No full textIn this work, a drop-and-measure optofluidic platform that exploits capillary microfluidic concepts to infiltrate high-aspect-ratio (HAR) one-dimensional (1D) silicon/air photonic crystals (PhCs), this latter being used as sensing ele-ments, is reported. The platform, which is fabricated by electrochemical micromachining (ECM) technology, is op-tically characterized by measuring PhC reflectivity spectra upon capillary infiltration of liquids with different refrac-tive indices into the PhC air-gaps. Fiber grooves integrated in the platform allow the measurements to be carried out using optical fibers positioned in front of the PhC. Good reliability, sensitivity, and limit of detection are obtained, with best sensitivity value of 310 nm/RIU and worst-case limit of detection of 10-3 RIU, which are comparable to pressure-driven state-of-the-art integrated refractometers
Band gap tuning of silicon micromachined 1D photonic crystals by thermal oxidation
No full textFabrication and optical testing of high-aspect-ratio 1-D photonic crystals, obtained by electrochemical micromachining of silicon, are discussed in this paper. The devices consist of high-aspect-ratio periodic (P = 4 μm) arrays of 1.22-μm-thick silicon walls separated by 2.78-μm-wide air gaps, with 100 μm etching depth. They were designed as hybrid quarter-wavelength reflectors with photonic bandgaps in the near-IR region, one in particular centered at λ = 1.55 μm. The fabrication process was improved to increase structure uniformity and strength. Thermal oxidation of the silicon structures was exploited to tune the wavelength position and width of the bandgaps. Fabricated devices, also with different silicon dioxide thicknesses, were optically tested by measuring their spectral reflectivity in the wavelength range of 1.0–1.7 μm. Experimental results were found in good agreement with the calculated spectra
High-Aspect-Ratio Photonic Crystals For Capillary Optofluidics: Towards Drop-And-Measure Platforms
No full textOptical characterization of alcohol-infiltrated one-dimensional silicon photonic crystals
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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