Currently, there are various techniques for clinical diagnosis of infections. During the last pandemic caused by Sars-CoV-2, the importance and need for rapid, economical and accessible diagnostic systems became evident. Demonstrating that they are fundamental tools in the prevention and control of diseases. Thus, Point-of-Care (PoC) devices emerge as an alternative with the potential to improve access to the diagnosis of infectious diseases. These are devices that allow immediate diagnosis in low-complexity centers, reducing costs, streamlining the analysis, and, above all, considerably increasing the confidence intervals of the diagnoses. Many of the most used clinical diagnostic techniques base their determination on optical techniques, mostly colorimetric and fluorescent. These types of determinations are gaining wide attention as non-destructive tools, visible to the human eye, and capable of providing real-time and in-situ responses. The present work seeks to provide alternatives for better PoC diagnostic systems. We will focus on colorimetric determinations, widely used in nucleic acid amplification tests. However, they have the disadvantage of depending, in certain cases, on the subjectivity of the person analyzing the sample (visual diagnosis). Following this, a portable colorimetric device was developed, capable of objectively discretizing between positive and negative tests. Specifically, by performing spectral analysis of each sample and evaluating its absorbance in the visible spectrum.
In recent years, Argentina and countries of the region, have suffered epidemics associated with arboviruses, mainly Dengue and more recently Zika and Chikungunya. On the other hand, since the worldwide pandemic of SARS-CoV-2 (COVID-19), people’s health and the economic support of their countries have been seriously affected. It is necessary to have economic and faster diagnostic tools that allows evaluating samples of patients with symptoms. With this objective, diagnostic systems called point of care have been recently developed. These systems are defined as medical diagnostic testing at or near the point of care (that is, at the time and place of patient care). Specifically, in this work, a bio-photonic device has been developed. This instrument is able to detect certain diseases by means of a luminescence spectral analysis. This method can be conducted for saliva samples. The system consists in the fluorescence signal detection generated by a specific probe of the target viral genome, that coupled to isothermal amplification reaction, allowing the detection of the pathogen in the sample. The device excites the sample to be analyzed with light (led or semiconductor lasers with specific wavelengths) thus it triggers a spontaneous emission of the fluorophore bound to the specific probe. The emitted fluorescence is suitably filtered using interferential filters. These filters limit the spectral regions and allow discriminating the analysis band. Under these conditions, a signal is registered in a built-in detector and, depending on the signal level, define the case as positive or negative. All the analysis is done autonomously inside the developed device through an integrated control system and it is connected to a portable device to show the results wirelessly.
Femtosecond laser pulse systems allows to modify in a precise and permanent way the optical properties of a transparent materials. This process enables the direct writing of guiding structures in materials, commonly known as waveguides, which are the base for optical circuit fabrication. It is our interest to study the main characteristics of the waveguides manufactured by the laser micromachining technique. Here, an analysis of the resulting refractive index profile has been carried out. This characteristic is essential for the design and simulation of integrated optical circuits. In particular we have developed our research on the study of light coupling in a pair of type II waveguides made in Lithium Niobate (LiNbO3). These experimental backgrounds provide us with elements to adjust and test the retrieved profile. Taking into account different distance between tracks and writing energies, it is well known that the coupling length changes and the coupling ratio too. Then this study allows us to reconstruct the refractive index profile according to its manufacturing conditions. Modeling of the refractive index distribution profile is a key parameter to perform beam propagation mode simulations (BPM) to achieve more realistic results. So, by means of this method it is possible to obtain a general procedure to describe the characteristics of these kinds of waveguides. As a model test, integrated waveguides were built to corroborate their light coupling. In a first stage it is designed through BPM simulations then it is manufactured in an X-cut LiNbO3 crystal in order to check its operation according to the simulations carried out.
An optical fiber ring resonator (OFRR), a wavelength sensor for testing a single-mode laser system in a wide range of temperature, is presented. We will show that it is possible to calibrate, in relative form, a scale of wavelength, to determine, accurately enough, a thermally induced laser detuning, using the free spectral range of an OFRR. The optical circuit was constructed using 2 × 2 (50/50) optical fiber coupler obtaining an OFRR of 10-cm ring radius. A single-mode diode laser system has been launched into the OFRR, and different experiments have been performed. We tested the OFRR performance, considering fluctuations in the laser wavelength caused by small temperature instabilities, measuring the output intensity from the ring resonator. Theoretical simulations and experimental results were in agreement with the expected behavior. Furthermore, OFRR systems can be used as an excellent control tool to test the wavelength stability for a narrowband laser diode and act as a part of a control system.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.