Sensor-Embedded Face Masks for Detection of Volatiles in Breath: A Proof of Concept Study

The correlation between breath volatilome and health is prompting a growing interest in the development of sensors optimized for breath analysis. On the other hand, the outbreak of COVID-19 evidenced that breath is a vehicle of infection; thus, the introduction of low-cost and disposable devices is becoming urgent for a clinical implementation of breath analysis. In this paper, a proof of concept about the functionalization of face masks is provided. Porphyrin-based sensors are among the most performant devices for breath analysis, but since porphyrins are scarcely conductive, they make use of costly and bulky mass or optical transducers. To overcome this drawback, we introduce here a hybrid material made of conducting polymer and porphyrins. The resulting material can be easily deposited on the internal surface of standard FFP face masks producing resistive sensors that retain the chemical sensitivity of porphyrins implementing their combinatorial selectivity for the identification of volatile compounds and the classification of complex samples. The sensitivity of sensors has been tested with respect to a set of seven volatile compounds representative of diverse chemical families. Sensors react to all compounds but with a different sensitivity pattern. Functionalized face masks have been tested in a proof-of-concept test aimed at identifying changes of breath due to the ingestion of beverages (coffee and wine) and solid food (banana- and mint-flavored candies). Results indicate that sensors can detect volatile compounds against the background of normal breath VOCs, suggesting the possibility to embed sensors in face masks for extensive breath analysis

Efficient Chemical Surface Modification Protocol on SiO2 Transducers Applied to MMP9 Biosensing

The bioreceptor immobilization process (biofunctionalization) turns to be one of the bottlenecks when developing a competent and high sensitivity label-free biosensor. Classical approaches seem to be effective but not efficient. Although biosensing capacities are shown in many cases, the performance of the biosensor is truncated by the inefficacious biofunctionalization protocol and the lack of reproducibility. In this work, we describe a unique biofunctionalization protocol based on chemical surface modification through silane chemistry on SiO2 optical sensing transducers. Even though silane chemistry is commonly used for sensing applications, here we present a different mode of operation, applying an unusual silane compound used for this purpose (3-Ethoxydimethylsilyl)propylamine, APDMS, able to create ordered monolayers, and minimizing fouling events. To endorse this protocol as a feasible method for biofunctionalization, we performed multiple surface characterization techniques after all the process steps: Contact angle (CA), X-ray photoelectron spectroscopy (XPS), ellipsometry, and fluorescence microscopy. Finally, to evidence the outputs from the SiO2 surface characterization, we used those SiO2 surfaces as optical transducers for the label-free biosensing of matrix metalloproteinase 9 (MMP9). We found and demonstrated that the originally designed protocol is reproducible, stable, and suitable for SiO2-based optical sensing transducers.

MagnetoPlasmonic Waves/HOMO-LUMO Free π-Electron Transitions Coupling in Organic Macrocycles and Their Effect in Sensing Applications

Optical and magneto-optical surface plasmon resonance (MOSPR) characterization and preliminary sensing test onto single- and multi-layers of two organic macrocycles have been performed; TbPc2(OC11H21)8 phthalocyanine and CoCoPo2 porphyrin were deposited by the Langmuir-Schäfer (LS) technique onto proper Au/Co/Au magneto-optical transducers. Investigations of the MOSPR properties in Kretschmann configuration by angular modulation, gives us an indication about the potential discrimination of two organic macrocycles with absorption electronic transition in and out of the propagating plasmon energy spectral range. An improved molecular vapors sensitivity increase by the MOSPR sensing probe can be demonstrated depending on the overlap between the plasmonic probe energy and the absorption electronic transitions of the macrocycles under investigation. If the interaction between the plasmon energy and molecular HOMO-LUMO transition is preserved, a variation in the complex refractive index takes place. Under this condition, the magneto-plasmonic effect reported as 1/|MOSPR| signal allows us to increase the detection of molecules deposited onto the plasmonic transducer and their gas sensing capacity. The detection mechanism appears strongly enhanced if the Plasmon Wave/HOMO-LUMO transitions energy are in resonance. Under coupling conditions, a different volatile organic compounds (VOC) sensing capability has been demonstrated using n-butylamine as the trial molecule.

Microbial Biosensors as Pesticide Detector: An Overview

Farmers are highly dependent upon agrochemicals to boost crop production through soil fertilization and and insect pests, pathogens, parasites, and weeds management . However, contentious application of agrochemicals on the farm has aggravated residual accumulation and has become problematic for environmental safety besides causing disease to humans and other animals. Thus, the analysis of chemical residues from the environment is vital for policymakers and communities. Mostly, chemists were devoted to analyzing the existing contaminants from different sources by using highly sophisticated chromatographic equipment, although it is time taking, laborious, costly, and that required well-trained professionals. However, biosensors are more important to analyze chemical contaminants from different samples using various bioreporters integrated with electrochemical and optical transducers. Microbes are metabolically diverse, amenable for genetic engineering, cost effective in culturing, and tolerant to diverse conditions. Thus, microbial biosensor is capturing attention and becoming more effective for environmental monitoring. Therefore, this review assessed the implication of microbial biosensors for pesticide detection and the role of genetic engineering for strain improvement.

Far field superlensing inside biological media through a nanorod lens using spatiotemporal information

Far field superlensing of light has generated great attention in optical focusing and imaging applications. The capability of metamaterials to convert evanescent waves to propagative waves has led to numerous proposals in this regard. The common drawback of these approaches is their poor performance inside strongly scattering media like biological samples. Here, we use a metamaterial structure made out of aluminum nanorods in conjunction with time-reversal technique to exploit all temporal and spatial degrees of freedom for superlensing. Using broadband optics, we numerically show that this structure can perform focusing inside biological tissues with a resolution of λ/10. Moreover, for the imaging scheme we propose the entropy criterion for the image reconstruction step to reduce the number of required optical transducers. We propose an imaging scenario to reconstruct the spreading pattern of a diffusive material inside a tissue. In this way super-resolution images are obtained.

Controlling the interfacial reactions and environment of rare-earth ions in thin oxide films towards wafer-scalable quantum technologies

Rare earth (RE) doped oxides have demonstrated a great potential for photonic applications and have also appeared as promising candidates for quantum memories and microwave to optical transducers. Here, we...

IMPROVEMENT OF OPTICAL-ELECTRONIC MEANS FOR INCREASE OF EFFICIENCY OF COMBAT EMPLOYMENT OF THE ARMORED WEAPONS UNDER LIMITED VISIBILITY CONDITIONS

According to the experience of hostilities, including during the JFO (ATO), today much attention is paid by military experts to the development and improvement of optical and optoelectronic devices. This is due to the continuous improvement and development of new generation weapons systems that have improved tactical and technical characteristics, reduces the time spent by objects in the area of detection and damage, reduces the visibility of objects, increases their protection from interference and countermeasures, changes their tactics. The main advantages of optoelectronic devices are: the secrecy of their use, in contrast to radar and radio equipment, they do not require additional systems of protection against interference; relative simplicity of design, operation and small dimensions; low energy consumption; ecological purity. The current state of threats to Ukraine's sovereignty and territorial integrity, first of all the ongoing aggression of the Russian Federation, requires the introduction of necessary ways to counter them, improving approaches to the formation of military-technical policy, taking into account the urgent need to update existing weapons and military (special) equipment. There is a need to create electron-optical transducers or matrix devices of other types that work in the visible and infrared ranges, for night vision devices, and opto-electronic systems for detection (registration) of laser radiation of rangefinders, control systems for homing projectiles, missiles in the optical range spectrum. The paper describes the areas of improvement of optoelectronic means of surveillance, detection and aiming in order to increase the effectiveness of combat employment of armored weapons. The relevance of the study lies in the need to introduce fundamentally new concepts for the integration of optical and optoelectronic devices.

A method to compute detection range for electro optical transducers used for anti-ship missiles guidance

In this paper we briefly present a method to compute detection range for electro optical transducers used for naval missiles guidance.