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Hyperspectral and Color Imaging of Solvent Vapor Sorption Into Porous Silicon
摘要： A porous silicon thin film photonic crystal (rugate) sample with both a radial gradient in the rugate reflectance band wavelength and two spatially separated pore-wall surface chemistries (methylated and oxidized) was monitored by hyperspectral and color imaging while it was dosed with vapors of acetone, ethanol, heptane, 2-propanol, and toluene at concentrations ranging from 100 to 3,000 mg m?3. The shift in the wavelength of the rugate reflectance band maximum at each position along a transect across the two surface chemistries, as derived from the hyperspectral imaging, could discriminate between the different solvents and concentrations of solvents, while the change in hue derived from the color camera data along an analogous transect did not provide discrimination. The discrimination between solvents was mainly due to the two different surface chemistries, and the gradient associated with the change in the rugate reflectance band wavelength did not affect the selectivity significantly. There was spatial variability in the spectral and color responses along the transect independent of the overall rugate reflectance band wavelength gradient and pore-wall surface chemistries, and this was attributed to factors such as the presence of striations in the silicon wafer from which the porous silicon was prepared.
关键词： sensor,porous silicon,hyperspectral imaging,surface modification,vapor sensing
更新于2025-09-23 15:22:29
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Rapid liquid-phase microextraction of analytes from complex samples on superwetting porous silicon for onsite SALDI-MS analysis
摘要： To simplify the pretreatment process of complex samples is a key step for rapid detection. Herein, we report a single-step method to rapidly extract analytes with liquid-phase microextraction (LPME) from complex samples on a superwetting porous silicon (PSi) for onsite detection with surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). The operation time is less than 3 min with this simple method. The limit of detection (LOD) of malachite green in lake water is lowered to 10-13 M, that of verapamil and methadone in whole blood is down to 10-11 M and 10-13 M, in urine is 10-13 M and 10-14 M, respectively; and the ranges of quantification is up to 8 or 9 orders of magnitude with high precision (coefficients of determination (R2) > 0.98) for the complex samples. This method could provide an approach to directly extract target compounds from complex samples on substrate for SALDI-MS analysis.
关键词： SALDI-MS,porous silicon,onsite,rapid liquid-phase microextraction,superhydrophobic
更新于2025-09-23 15:22:29
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Layer by layer deposition of alternate carbon nanotubes and Ni films for efficient multilayer thin film temperature gauges
摘要： This study reports a novel approach for growing multilayer thin films consisting of alternate layers of carbon nanotubes (CNT) and nickel on Si (1 0 0) substrates and justifies their use in thin film temperature sensors. A low pressure chemical vapor deposition system was employed for synthesizing CNT films, while Ni films were deposited by electrodeposition. Porous-Si was used as substrate to increase adhesion between the layers of the multilayer structure. The structure of the multilayer films and the quality of the CNT grown were analyzed using several characterization methods, including scanning electron microscopy, x-ray photoelectron spectroscopy, x-ray auger electron spectroscopy and Raman spectroscopy. The electrical characteristics were investigated using a van der Pauw setup and the effect of the increasing number of CNT layers in the multilayer structure was studied. The sensitivity of the multilayer film was found to increase with increasing number of CNT layers, despite the decrease of the temperature coefficient of resistance. On the other hand, the initial resistance was found to increase. Results indicated that these multilayer structures are appropriate for fabricating highly sensitive thin film gauges that can detect lower heat fluxes with more accuracy.
关键词： carbon nanotubes,thin film gauges,surface and interface chemistry,porous silicon,adhesion sensing,x-ray photoelectron spectroscopy
更新于2025-09-23 15:22:29
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Optimising porous silicon Bragg reflectors for narrow spectral resonances
摘要： Achieving sharp spectral resonances in porous silicon based photonic structures is of significant practical importance for improving the accuracy of refractive index-based sensing in chemical and biochemical applications. Here, we show that by compensating for depth related heterogeneities in the etching conditions, we are able to reduce the porosity modulation in Bragg reflectors to below 1% and achieve absorption limited spectral widths of 7 nm in the visible part of the spectrum. Such narrowband Bragg reflectors provide markedly improved sensing capability for real-time monitoring of refractive index changes compared with reflectors with broader spectral features.
关键词： optical sensing,porous silicon,Bragg reflectors,narrow spectral resonances,refractive index-based sensing
更新于2025-09-23 15:21:21
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Hybrid III-V/SiGe solar cells on Si substrates and porous Si substrates
摘要： A tandem GaAsP/SiGe solar cell has been developed employing group-IV reverse buffer layers grown on silicon substrates with a subsurface porous layer. Reverse buffer layers facilitate a reduction in the threading dislocation density with limited thicknesses, but ease the appearance of cracks, as observed in previous designs grown on regular Si substrates. In this new design, a porous silicon layer has been incorporated close to the substrate surface. The ductility of this layer helps repress the propagation of cracks, diminishing the problems of low shunt resistance and thus improving solar cell performance. The first results of this new architecture are presented here.
关键词： tandem on silicon,porous silicon,reverse buffer layers,III-V on silicon,GaAsP/SiGe
更新于2025-09-23 15:21:01
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Cellular Internalization-Induced Aggregation of Porous Silicon Nanoparticles for Ultrasound Imaging and Protein-Mediated Protection of Stem Cells
摘要： Nanotechnology employs multifunctional engineered materials in the nanoscale range that provides many opportunities for translational stem cell research and therapy. Here, a cell-penetrating peptide (virus-1 transactivator of transcription)–conjugated, porous silicon nanoparticle (TPSi NP) loaded with the Wnt3a protein to increase both the cell survival rate and the delivery precision of stem cell transplantation via a combinational theranostic strategy is presented. The TPSi NP with a pore size of 10.7 nm and inorganic framework enables high-efficiency loading of Wnt3a, prolongs Wnt3a release, and increases antioxidative stress activity in the labeled mesenchymal stem cells (MSCs), which are highly beneficial properties for cell protection in stem cell therapy for myocardial infarction. It is confirmed that the intracellular aggregation of TPSi NPs can highly amplify the acoustic scattering of the labeled MSCs, resulting in a 2.3-fold increase in the ultrasound (US) signal compared with that of unlabeled MSCs. The translational potential of the designed nanoagent for real-time US imaging–guided stem cell transplantation is confirmed via intramyocardial injection of labeled MSCs in a nude mouse model. It is proposed that the intracellular aggregation of protein drug–loaded TPSi NPs could be a simple but robust strategy for improving the therapeutic effect of stem cell therapy.
关键词： drug delivery,porous silicon,ultrasound imaging,cell protection,cell labeling
更新于2025-09-23 15:21:01
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[IEEE 2018 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - Saint Petersburg, Russia (2018.10.22-2018.10.23)] 2018 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - Porous Silicon as a Material for Nanocomposites and the Effect of its Parameters on the Morphology of Silver Clusters
摘要： On the example of the por-Si/Ag composites it is demonstrated the ability to control the morphology of the guest material (Ag) by changing the parameters of the porous media (por-Si). Two groups of key parameters of porous materials important for creating composites based on them are discussed. Porous silicon was obtained by electrochemical anodic etching. The introducing Ag into the pores was performed by the cathodic electrochemical deposition. It is observed the increasing the anodizing time is leads to the noticeably changes of wetting angle of por-Si, and, in turn, significantly affects the morphology of Ag clusters. The growth mechanisms of Ag clusters on the por-Si surface and the fields of its potential application are discussed.
关键词： porous texture,surface properties,porous silicon composites,por-Si/Ag composites,electrochemical deposition,surface functionality,silver clusters
更新于2025-09-23 15:19:57
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Decoration of porous silicon with gold nanoparticles via layer-by-layer nano-assembly for interferometric and hybrid photonic/plasmonic (bio)sensing
摘要： Gold nanoparticle layers (AuNPLs) enable the coupling of morphological, optical, and electrical properties of gold nanoparticles (AuNPs) with tailored and specific surface topography, making them exploitable in many bio-applications (e.g. biosensing, drug delivery, photothermal therapy). Herein, we report the formation of AuNPLs on porous silicon (PSi) interferometers and distributed Bragg reflectors (DBRs) for (bio)sensing applications via layer-by-layer (LbL) nano-assembling of a positively charged polyelectrolyte, namely polyallylamine hydrochloride (PAH), and negatively charged citrate-capped AuNPs. Decoration of PSi interferometers with AuNPLs enhances the Fabry-Perot fringe contrast due to increased surface reflectivity, resulting in an augmented sensitivity for both bulk and surface refractive index sensing, using NaCl aqueous solutions to infiltrate the pores (roughly 4.5-fold), in the former, and unspecific bovine serum albumin (BSA) adsorption on the pore surface (roughly 2.6-fold), in the latter. Sensitivity enhancing is also confirmed for affinity and selective biosensing of streptavidin (roughly 2.5-fold) using a biotinylated polymer, namely, negatively-charged poly(methacrylic acid) (b-PMAA). Further, decoration of PSi DBR with AuNPLs envisages building up a hybrid photonic/plasmonic optical sensing platform. Indeed, both photonic (DBR stop-band) and plasmonic (localized surface plasmon resonance, LSPR) peaks of the hybrid structure are sensitive to changes of bulk refractive index (using 35% glucose aqueous solutions) and BSA unspecific adsorption. To the best of our knowledge, this is the first report about the formation of AuNPLs via LbL nano-assembly on PSi for i) the enhancing of the interferometric performance in (bio)sensing applications and ii) the building up of hybrid photonic/plasmonic platforms for sensing and perspective biosensing applications.
关键词： Layer-by-Layer (LbL) nano-assembly,Porous Silicon (PSi),Biosensor,Interferometer,Gold nanoparticles (AuNPs),Hybrid Photonic/Plasmonic,Distribute Bragg Reflector (DBR),Sensor
更新于2025-09-23 15:19:57
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Laser Annealing Enhanced the Photophysical Performance of Pt/n-PSi/ZnO/Pt-Based Photodetectors
摘要： Herein, the effect of pulsed Nd:YAG laser irradiation at different fluencies in air at room temperature on the performance of n-PSi/ZnO-based UV MSM photodetector was demonstrated. Thermal and photon energies were coupled to synthesize n-PSi/ZnO NCs heterojunctions. The porous silicon (PSi) films with nano-sized pore arrays were first prepared via photoelectrochemical etching (PECE) of n-type silicon wafers with 45 mA/cm2 current density for a duration of 30 min. This was followed by radio frequency sputtering (RFS) of ZnO on PSi at 700 oC and irradiating with a Nd: YAG laser pulses with laser fluence of 40 mJ/cm2. X-ray diffraction analysis indicates the formation of ZnO wurtzite hexagonal crystal structure of n-PSi/ZnO NCs, where the crystallite size decreases (96-29 nm) with number of pulses. Field emission electron scanning microscopy and atomic force microscopy reveal porous nanostructure, arrays of nearly spherically shape particles homogeneously distributed on the entire surface where roughness increases (84-139 nm) with number of pulses. Photoluminescence spectroscopy reveals intrinsic band-to-band transition, donor-acceptor pair emission and quenching of the broadband intensity related to improved of crystallinity, meanwhile the band gap energy of the n-PSi/ZnO NCs is found to decrease (3.26 – 3.13 V). The Nd:YAG laser annealing demonstrate a positive effect on the properties of n-PSi/ZnO NCs photodetector, exhibiting very high sensitivity (3772.92) and very short rise and recovery times (0.30 s and 0.26 s).
关键词： Porous silicon,n-PSi/ZnO junction,Nd-YAG laser,photodetectors
更新于2025-09-23 15:19:57
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Manufacturing and Characterization on aThree-Dimensional Random Resonator of Porous Silicon/TiO <sub/>2</sub> Nanowires for Continuous Light Pumping Lasing of Perovskite Quantum Dots
摘要： In recent years, all inorganic bismuth lead-halide perovskite nanocrystals [CsPbX3 (X ? Cl, Br, I)] have received extensive attention due to their high performance in °uorescence quantum yield, narrow emission spectrum, and adjustable emission range. However, the disadvantages of high cost and poor stability have greatly limited the development prospects of the material. Here, in order to develop a perovskite quantum dot lasing cavity with high chemical stability, high quality factor and low fabrication cost, we have successfully fabricated a 3D random cavity device based on porous silicon/TiO2 nanowires. A TiO2 nanowire is grown on the porous silicon to form a 3D resonant cavity, and a perovskite quantum dot is spin-coated on the surface of the 3D resonant cavity to form a novel 3D complex ˉlm. The novel structure enhances the chemical stability and lasing quality factor of the resonant cavity while the °uorescence generated by the large quantum dots in the spatial interference structure constitutes the feedback loop, which will provide favorable support for the development of information optics.
关键词： porous silicon,Perovskite quantum dots,TiO2,resonators
更新于2025-09-23 15:19:57