Thermal lens spectroscopy, reliant on the thermal lens effect, offers a sensitive and non-invasive means for analyzing samples through their light absorption-induced refractive index changes. We aimed to enhance sensitivity using a novel differential method. This involved measuring the signal at the center point of the probe beam spot and comparing it with the signal obtained through spatial...
Piezoresponse force microscopy (PFM) is a unique technique that enables the study of ferroelectric properties at the nanoscale level. Scientific advancements and the proposal of new ferroelectric systems have encouraged the development of several variations of PFM. Specifically, for ferroelectrics with poor mechanical properties, hybrid-PFM (H-PFM) has been introduced.
Within force-distance...
This work shows an electro-photonic characterization of light emitting capacitors (LECs) based on silicon rich oxide films (SRO) as active material. The LEC structure is based on metal-oxide-semiconductor (MOS) capacitor with polysilicon as top M-electrode and p-type silicon as semiconductor substrate. These devices exhibit a high current at low voltages with some current jumps/drops that...
Drinking water is a vital resource. Assessing water quality is a health issue. Harmful substances such as heavy metals need to be in concentrations low enough for safe human consumption. It is also necessary to monitor other water characteristics. For instance, water hardness, related with calcium carbonate concentration, has an impact in detergent use and scale formation.
With the advent of...
Reactive sputtering is a very useful technique, particularly to prepare inhomogeneous interference filters, where refractive index changes smoothly during deposition. In such context, precise control over the involved parameters becomes imperative to obtain a good reproduction of the optical properties [1]. This study employed a pulsed direct current (pulsed DC) power source to investigate the...
All inorganics halide lead perovskites have emerged as promising candidates for optoelectronic devices due to their exceptional properties, including high absorption coefficients, tunable bandgaps, and superior charge carrier mobilities. These attributes make them ideal for applications in solar cells, light-emitting diodes, and photodetectors. However, a significant challenge limiting their...
Two-dimensional materials, such as graphene, have acquired significant attention due to their unique electrical, optical, and mechanical properties, making them highly promising for various applications including electronics, optoelectronics, and energy storage. This study focuses on graphene oxide (GO) samples with varying degrees of oxidation, synthesized using a modified Hummers’ method....
The diabetes is a chronic disease that is detected by measuring the glucose levels in the blood. A noninvasive alternative method was proposed for measuring the gas concentration emitted by individuals with this disease, where the compounds acetone (Ace) and ethanol (EtOH) are considered as biomarkers, and indicators of the disease. A gas sensor array was constructed using quartz crystal...
This study presents an innovative methodology for determining the thermal diffusivity in thin films of metals and organic materials using advanced thermographic techniques. A diode laser pulse is employed to create a thermal contrast on the sample surfaces, with the resulting temperature evolution monitored by an infrared camera. The collected data is then processed using a MATLAB-developed...
Here, we have designed a metal/superconductor (Al/Nb) metamaterial to modulate its superconducting transition temperature Tc and response to external magnetic fields (Ha). The coherence length of the Cooper pairs of bulk Nb regulates the thickness of the Nb and Al layers; thus, the filling factor [fNb = dNb/( dNb + dAl)] of the metamaterial was set to 0.88 and 0.12, which were contrasted to a...
The study of the optoelectronic properties of films that compose a solar cell have significant impact in the optimization of the best configuration of a solar cell. Among these properties, the dielectric function of the materials is one of the most relevant. In this work, the study of the dielectric function <ε> of Cu3Se2 thin films growth over Glass/FTO by electrodeposition. The ellipsometric...
The kidney damage present in septic shock is one of its most serious and irreversible symptoms. One of the key biomarkers of kidney damage is the presence of hemoglobin in the urine, which can indicate hematuria and acute kidney injury. Photoacoustic spectroscopy has shown its capacity and sensitivity as an alternative tool for the detection of hemoglobin in biological samples, including...
With the increasing global population and advancements in portable technology, there is a growing demand for improved energy storage devices like supercapacitors, which offer high-power performance, rapid charge/discharge cycles, and longer service life than batteries despite storing less energy. To enhance supercapacitor performance, this study focuses on developing electrospun membranes...
Recent research has highlighted supercapacitors as promising candidates for energy storage applications due to their unique combination of rapid charge-discharge characteristics, low weight, flexibility, portability, and exceptional power density. These advantageous characteristics have facilitated their integration into emerging technologies within the aerospace sector, electric vehicles, and...
Traditional optical interference filters have been manufactured with discrete thicknesses since the 1930s, when anti-reflection coatings were first introduced in Zeiss microscopes. In most standard applications, the theoretical calculation of the optical response of a given filter is achieved by propagating electromagnetic waves through a continuous medium, a procedure known as analysis....
Machine learning algorithms have become indispensable tools across all branches of science in recent years. These algorithms, comprised of sets of neural networks, excel at identifying and classifying patterns within datasets, proving to be comparable to human capacity in classification tasks. Moreover, they offer the advantage of completing tasks much faster than a human could. In this study,...
This study presents the micro-manufacturing process and radio frequency (RF) evaluation of a Metal-Semiconductor-Metal (MSM) type photodetector, utilizing reduced graphene oxide (rGO) decorated with nickel nanoparticles as the photosensitive material for light detection. The photodetector was initially designed with a Ground-Signal-Ground (G-S-G) configuration to determine the spacing between...
Concrete is one of the most widely used materials in civil construction. It is a rock created artificially by mixing fine and coarse aggregate components, cement, and water. In this research work, the analysis of the interfacial transition zone in the concrete microstructure by adding different graphite contents, partially replacing the weight of cement, is presented. The morphology and...
An analysis of the reflectance spectra in porous silicon samples is reported to determine the effect of the percentage of porosity on their optical absorption capacity in the visible spectrum. Porous silicon (PS) samples were prepared by electrochemical anodization at 5, 10, 15, 20 and 30 minutes. A crystalline silicon (CS) wafer with orientation (100), phosphorus-doped n-type (thickness: 500...
In dual beam, mode mismatched transient thermal lens spectroscopy (TLS), the evolution with time of the probe beam intensity after the sample´s excitation is measured at the far field and, in the conventional configuration, in the center of the beam. For samples with a negative temperature coefficient of the refractive index, a divergent thermal lens is formed after excitation, so that this...
The application of the laser-spot active lock-in infrared thermography technique in a front
detection configuration for the simultaneous measurement of the thermal conductivity (k)
and diffusivity (D) of isotropic solids taking advantage of the heat losses by conduction
from the sample to the surrounding air has been reported recently []. In this method, an
intensity periodically modulated...
In this study, we obtained films with the NiFe/Cu/NiFe strucure were obtained by cathodic erosion, with the NiFe layers maintaining a constant thickness of 100 nm and the intermediate copper (Cu) varying in thickness from 100, 200, and 300 nm. The structural characterization was carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Consistent with previous literature...
The study of porous silicon has gained prominence due to modifications in its thermal and optical properties stemming from the formation of a porous layer, expanding its applications from sensors development to solar energy conversion systems design. One of the most commonly employed techniques for its fabrication is electrochemical etching; where a mayor challenge lies in achieving...
The X-ray photoelectron spectroscopy technique has been applied to study compounds or oxidation states of elements with the principal objet of stablish whether correlations exists between electron binding energy and the formal charge. Natural polymer-based nanocomposites, silver nanoparticles act as nanofillers with potential in biomedical industry due to antimicrobial activity. Many methods...
The discussion of this works is focus about the temperature field induced by thermal losses in these components, highlighting the standard form of heating in some regions of interest generated with the method of Thermoreflectance images, using polysilicon Greek Cross and Cross-Bridge Test Structures. The generation of these images are obtained by a laser probe beam on the surface of the...
This study explores Atomic Layer Deposition (ALD) for engineering optical waveguides and filters. Al2O3-Y2O3 nanolaminates and Al2O3 thin films were fabricated using ALD, demonstrating their potential as waveguides with low propagation loss. The influence of the oxygen source (H2O vs. O3) in ALD Al2O3 waveguides was investigated, revealing lower losses for O3-based films. TiO2-x films with...
The strategic integration of nanomaterials into polyurethane-based coatings offers considerable improvements with metal oxide nanoparticles providing enhanced properties to the coatings. This approach aims to contribute insights for developing materials in surface protection within demanding environments, fostering innovation in the design of materials with self-healing properties. To enhance...
