Surveillance of population immunity against infectious diseases is critical for pandemic management and risk assessment of future outbreaks. However, current serological tests fall short in accurately identifying immunity profiles from diverse populations. We present a label-free, rapid, multiplexed, and variant-sensitive nanoplasmonic biosensor to quantify antibodies against multiple SARS-CoV-2 antigens from small human blood samples. We combined a machine learning model with antigen-specific antibody patterns measured from four different cohorts with known COVID-19 immunity. Subsequently, we tested our model on 100 blind human samples and determine that our findings are consistent with public epidemiological data showing that our nanobiosensor can help monitor population health during a pandemic.
Fiber optic sensor technology is considered as a promising candidate for the monitoring of biophysical parameters due to its sensitivity to strain and temperature, immunity to electromagnetic interference, lightweight and opportunity to be mounted on the textiles. Therefore, this paper suggests using one of the fiber optic technologies, namely Fiber Bragg Grating (FBG) sensors, for the respiratory rate monitoring of the hospital patients or sportsmen. Two FBG arrays consisting of 5 sensors each have been sewed to two elastic belts. The belts have been put on volunteer‘s chest and abdomen because the expansion of those regions causes the elastic belts to elongate and, as a result, FBG arrays experience strain changes. The use of ten FBGs located in different regions is required to use the diversity technique, which allows increasing the accuracy of the result by combining output from multiple sensing points. Therefore, a special algorithm has been used to analyze the strain pattern detected by all ten FBGs and to reconstruct the respiratory rate based on them. The obtained breathing rate of the volunteer has been compared with the reference rate measured by a mobile application. Several sets of experiments have been performed in order to identify the influence of the volunteer‘s position and speed of breathing on the accuracy of the measurements.
This work presents a method of needle shape reconstruction, which can serve as potential guidance technology for minimally invasive surgeries, such as epidural anesthesia. The suggested technology applies four optical fibers, which are glued along the Tuohy needle at an angle of 90 degrees from each other thus creating two pairs of opposite fibers. Optical fibers are used to achieve high resolution distributed strain sensing along the needle, which working principle is based on the Optical Backscattering Reflectometry (OBR). Since OBR is limited to a single-fiber measurement and the setup requires four sensing fibers, the multiplexing method has been suggested. The multiplexing approach is based on the spatial separation of four high-scattering nanoparticles doped fibers (used as sensing fibers) by the single-mode regions with a lower scattering level. As a result of such configuration, the strain sensed by each sensing point along the pairs of opposite fibers is used to reconstruct the inclination of the needle in two perpendicular directions. The approach has been tested in the needle calibration experiment when it has been manually bent to different directions and the setup allowed to accurately reconstruct the direction of the needle‘s inclination. The potential application of the setup for the minimally invasive therapies has been tested on the example of epidural anesthesia. The needle has been inserted into a medical phantom, which models human spinal anatomy, and the shape of the needle at each moment of insertion has been reconstructed.
Nowadays, the application of nanoparticles for biomedical purposes is a promising and innovative tool for the thermal therapy of tumors. Gold nanoparticles are distinguished by their tunable optical properties, biocompatibility, and ease of synthesis. The ability of gold nanoparticles to absorb light at near-infrared region (NIR) to generate localized heat allows temperature elevation and optimizing the temperature distribution during short-time laser ablation. The synthesized 20-nm gold nanoparticles injected on the surface of the tissue demonstrated rapid and diffused heat increase enlarging the shape of the treated region compared to the pristine tissue. Another advantage of this work is the proposed optical fiber distributed sensing network over the laser ablation assisted with nanomaterials. The sensing system uses single-mode enhanced-backscattering optical fibers doped with MgO nanoparticles; it achieves narrow spatial resolution, which demonstrates accurate temperature distribution monitoring in real time, in 2-dimensions over 5.4 cm2 area at 16 sensing points per fiber. The obtained sensing data allowed to calculate the treated area and provided the information when the ablation process should be terminated in order to avoid the vaporization of tissue after reaching the temperature of 100 °C. The calculated damage threshold (>60 °C) areas are 2.57 cm2 with gold nanoparticles, compared to 1.33 mm2 pristine. The results of this work provide the solution to two issues existing during laser ablation that are possible damage of undesired area and the ability to precisely monitor the temperature in real time that is compatible to MRI.
Laser ablation (LA) has shown promising results in selective treatment of solid tumors. Recently, nanomaterials, in particular nanoparticles (NPs), have been proposed as mediators for laser tissue ablation due to their high optical absorption coefficients. In this work, we report distributed fiber optic temperature sensors for monitoring of NPmediated LA in ex-vivo porcine liver. This study aims at improving the outcomes of LA through magnetite NPsenhanced LA with in-situ thermal profiling. Such thermal profiling is achieved with optical backscatter reflectometer interrogating a set of custom-made MgO-doped optical fibers exhibiting enhanced scattering profiles. Fiber optic sensors, providing spatially resolved measurements, significantly outperform conventional thermocouples and imaging techniques. A minimally invasive LA setup is based on high power fiber coupled diode laser operating at 980 nm wavelength, with output power up to 30 W. Magnetite (Fe3O4) NPs are synthetized and locally injected within the tissue before performing LA. The sensing setup utilizes optical backscatter reflectometer that exploits Rayleigh backscattering to measure the temperature distribution with submillimeter spacing. Thermal maps, i.e. temperature distribution as a function of space and time, are reported highlighting thermal distribution within the ablated lesion and in off-target adjacent tissue. The influence of laser power and of NPs concentrations on the outcomes of LA is also investigated. Results demonstrate that injection of NPs into targeted area helps enhance conversion of light energy into thermal energy, thus increasing the efficacy of the ablation within the treated area, without overheating the adjacent off-target tissue.
Here a novel paradigm of fiber optics 3D shape sensing is presented. Fiber optics technology offers a great potential for minimal invasive medical applications. The approach is supported by two basic cornerstones: the first is the Optical Backscattering Reflectometry (OBR), which gives the possibility of distributed strain sensing along the length of fiber sensor installed on the needle; the second is the principle of simultaneous scattering-level multiplexing (SLMux), which permits to interrogate a parallel of optical sensor in the same OBR scan. SLMux, which overtakes the OBR limitation to the interrogation of a single optical sensor, is possible by using a custommade MgO nanoparticles doped fiber (NPDF), which presents a core doped with a randomly distributed pattern of particles. NP-fiber shows a backscattering power of more than 40 dB higher than a standard single-mode fibers (SMF). By splicing NP-fiber cuts with different SMF pigtail it is possible to achieve a parallel where the higher NP-fiber backscattering can be effectively discriminated. With this approach it is possible to pack several sensors along the needle length to detect all the strain components. Experimentally, a parallel of four sensors has been fixed along the length of an epidural needle at 90 degrees from each other. 3D shape sensing is achieved by strain measurement from each fibers and distributed strain sensing along the needle. As a result of strain elaboration, shape deformation and bending of the needle during its insertion into a custom-made phantom, which mimics human spine anatomy, have been obtained.
Distributed temperature sensing, achieved by Optical Backscattering Reflectometry (OBR), has potential in applications that require high sensitivity and resolution, such as thermal ablation. The working principle of OBR is based on monitoring the spectral signature of the light backscattered by the infinitesimal non-homogeneities inside the fiber, which changes as a result of strain or temperature variation. All the standard single-mode telecom optical fibers have almost the same scattering level, therefore, when multiple fibers are connected in parallel to the OBR, the instrument is unable to differentiate the pattern of each fiber. To overcome this issue, we proposed the use of fibers with different scattering level. Higher scattering can be achieved by creating a doping of MgO nanoparticles (size is 20-100 nm) in the fiber core, which results in roughly 50 dB increase of the scattering power. Several nanoparticles doped fibers (NPDF) have been spliced to standard single-mode fibers with variable lengths, in order to achieve spatial separation. The obtained fibers have been connected to the OBR by a 1x8 splitter. The backscattered spatial pattern consisted of several high-power regions separated by low-scattering zones given by fibers parallel. The proposed setup, applied in thermal ablation experiments, has shown that each sensing fiber is able to detect temperature variations distributed over the sensor length, and the scattering-level enabled multiplexing setup allows a detailed 2-dimensional temperature map. The resolution achieved in the pixel of the thermal map is in the order of millimeter. Moreover, the technique can be extended to obtain a 3D temperature map.
Optical Backscattering Reflectometry (OBR) can be used for one-dimensional distributed strain sensing of medical needles. To achieve 3D shape sensing the needle should be equipped with multiple optical fibers. A feasible configuration can be done using two pairs of parallel optical fibers, which will measure the strain in two directions perpendicular to a needle axis. However, OBR is limited to a single fiber sensing because of its inability to discriminate scattering patterns of different fibers. To achieve multiplexing, it is proposed to use nanoparticle doped fibers (NP-doped) with high scattering power and splice them to standard single-mode (SMF) pigtails with different lengths. As a result of such configuration, the NP-doped fibers, which are used as sensing fibers, are spatially separated by standard fibers.
Distributed sensing based on Optical Backscattering Reflectometry (OBR) is a promising solution for medical applications, such as thermal ablation. OBR working principle is based on the change in pattern of small reflections from non-homogeneities inside the fiber as a response to applied strain and temperature. The advantage of OBR is its high resolution and sensitivity. However, since the scattering level is the same for standard single-mode fibers, OBR is unable to discriminate the pattern of different fibers when they are connected in parallel to a single channel. As a result, OBR detection is limited to a single sensing fiber and does not allow multiplexing. This work proposed a method to overcome the aforementioned limitation by the use of high-scattering fibers. Such fibers are achieved by doping their core with magnesium oxide particles, which size varies from 20 to 100 nm. The backscattering level of nanoparticles doped fiber (NPDF) is 50 dB higher than of the standard fibers. Four NPDFs have been spliced to the standard single-mode pigtails with different length to achieve four sensing regions located at different distances from pigtails. The NPDF sensors have been connected to the OBR equipment by the use of optical couplers and the backscattered pattern has shown four high-scattered sensing regions separated by low-scattering regions from standard fibers. The proposed setup has been applied in the thermal ablation experiments and the 2-dimensional map of temperature change with time has been obtained.
Epidural anesthesia is the most diffused clinical practice described as a placement of a medical needle into an epidural space, an insertion of a catheter through the needle and an injection of anesthetic in order to numb the nerves. A skilled anesthesiologist penetrates the needle through tissue layers such as subcutaneous fat, interspinous ligament, intraspinous ligament, ligamentum flavum and reaches the target space. Currently, methods of positioning of the needle tip into the epidural space are based on subjective perception, which are not safe and accurate. In order to improve the effectiveness of the epidural space identification, this work proposes a sensorized optical fiber mounted externally on the needle. This medical device provides continuous and real-time measurements with the help of an optical backscattered reflectometry. When the needle is exposed to strain variations during its advancement, the intensity of backscattered light changes. By correlating the spectrum with the reference one, strain patterns can be produced. Obtained data can detect the needle passage from one tissue to the other in a custom made phantom, which mimics a human spinal anatomy. Specifically, needle passage from the stiff ligamentum flavum to the soft epidural space results in a significant strain drop and a consequent increase, which is considered as a crucial indicator of epidural space identification. The proposed device is advantageous over existing optical guidance: it does not obstruct the flow of a liquid in the inner side of the needle; the needle from the tip to the tail performs as a sensor.
Optical Backscatter Reflectometer (OBR), based on Optical Frequency Domain Reflectometry principles can transform a simple and cheap single mode fiber in an efficient spatially distributed (over the fiber length) sensor of temperature and strain variation. Nevertheless, the use of OBR is limited to function with a single sensing fiber. Connecting multiple fibers in parallel can be problematic. The scattering level of each fiber is of the same magnitude so that the backscattering cannot be discriminated. Unfortunately, particular medical applications, such as the guided insertion of needle or medical catheters, can benefit of multiple fiber sensors mounted in parallel. The adopted solution of switching between different sensors in different time frames if feasible, but it significantly reduces the interrogation frequency. In this work a new solution for overcoming this issue, by the use of a high scattering nano-particles doped fiber (NPDF), is proposed. This fiber presents a random distributed pattern of magnesium oxide nanoparticles, whose size varies between 20 to 100 nm, in the core. Its backscattering is 50 dB larger than a standard single mode fiber. The use a NPDF segment spliced to a standard single mode pigtail, with different lengths, such that the NPDF position corresponds to a pigtail on the other fibers, permits to connect them in parallel. Thus, the OBR can spatially resolve the NPDF high backscattering, since the single mode pigtail scattering is irrelevant. Experiments have shown positive results in the terms of temperature and strain discrimination.
Epidural anesthesia is a pain relief method achieved by injecting anesthetic into the epidural space using a medical catheter inserted in an epidural needle. To reach the epidural space, the needle penetrates through subcutaneous fat, interspinous ligament, intraspinous ligament and ligamentum flavum. Existing manual methods for epidural space identification are based on the decrease of pressure applied to the needle when it penetrates from the dense ligamentum flavum to the soft epidural space. The failure rate of the manual techniques is high. This work proposes to measure the strain using a single-mode optical fiber, mounted externally on the needle. By the use of an optical backscattering reflectometer, it is possible to achieve a distributed strain sensing over the whole length of the needle. The spectral intensity distribution of the scattered light changes when the optical fiber is exposed to strain variations, so a strain pattern can be retrieved by correlating the unperturbed spectrum to the perturbed one. According to the strain pattern, obtained during the needle insertion into a custom made phantom, which mimics the spinal anatomy, when the needle penetrates the ligamentum flavum, a significant strain increase is determined. When the needle pierces the soft epidural space, the strain slightly drops. The proposed design brings the following advantages: optical fiber embedded externally on the needle does not obstruct the flow of anesthetic fluid; the whole needle acts as a sensor which allows the operator to discriminate tissue layers as well as to define the epidural space.
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