Nanosensor Systems Research Articles

Machine Learning Techniques for Improving Nanosensors in Agroenvironmental Applications

Nanotechnology, nanosensors in particular, has increasingly drawn researchers’ attention in recent years since it has been shown to be a powerful tool for several fields like mining, robotics, medicine and agriculture amongst others. Challenges ahead, such as food availability, climate change and sustainability, have promoted such attention and pushed forward the use of nanosensors in agroindustry and environmental applications. However, issues with noise and confounding signals make the use of these tools a non-trivial technical challenge. Great advances in artificial intelligence, and more particularly machine learning, have provided new tools that have allowed researchers to improve the quality and functionality of nanosensor systems. This short review presents the latest work in the analysis of data from nanosensors using machine learning for agroenvironmental applications. It consists of an introduction to the topics of nanosensors and machine learning and the application of machine learning to the field of nanosensors. The rest of the paper consists of examples of the application of machine learning techniques to the utilisation of electrochemical, luminescent, SERS and colourimetric nanosensor classes. The final section consists of a short discussion and conclusion concerning the relevance of the material discussed in the review to the future of the agroenvironmental sector.

Effect of the magnetic field on the thermomechanical flexural wave propagation of embedded sandwich nanobeams

This work examines thermo-mechanical bending wave propagation in a sandwich nanobeam using advanced sandwich nanobeam and nanolocal strain gradient elasticity theories. The sandwich nanobeam is a unique structure with biocompatible ceramic ZrO2 and metal Ti6Al4V on the top and bottom sides. Sandwich nanobeam cores have functionally graded materials. This combination gives the nanobeam distinctive qualities and opens up many uses in diverse industries. The wave propagation equation is computed by applying the Navier method to the medium’s thermal, Lorentz, and viscoelastic equations of motion. The sandwich nanobeam is analyzed using four distinct models, taking into account its composition of ceramic and metal materials. The various factors that affect sandwich nanobeam bending wave propagation have been extensively studied. In the scenario where the magnetic field intensity is Hm = 0, an increase in temperature difference causes the wave frequency of all models (except Model 2) to decrease to zero, resulting in buckling. In Model 2, the sandwich nanobeam exhibits a phase velocity of 0.43 Km/s at ΔT = 0, which subsequently decreases by ∼9% to 0.39 km/s at ΔT = 500. These factors include the strength of the magnetic field, the impact of thermal loads, the nonlocal effect, the dimensions of the sandwich nanobeam, and the foundation’s influence. The findings of this research will help build nanosensor systems that can work in aerospace applications under extreme temperatures. These findings will contribute to the optimization of the design process, ensuring the reliability and functionality of the nanosensors under severe thermal conditions.

Different Diacetyl Perception Detected through MOX Sensors in Real-Time Analysis of Beer Samples

Beer is the most consumed alcoholic beverage; with 177.5 million kiloliters produced every year, it is one of the most relevant food products. Diacetyl is a typical byproduct of yeast metabolism that is formed during the fermentation inside breweries. The perception of this high volatile and butter-like flavor molecule varies according to the kind of beer, from a positive and highly sought characteristic to a characteristic that is avoided. Furthermore, its toxicity when inhaled has been proven. Typical diacetyl analysis includes voltametric detection and chromatographic analysis techniques. Using metal oxide sensors (MOS), this analysis can become fast and cost-effective, evaluating the differences in diacetyl concentrations through resistance variation. The S3+ (Nano Sensor Systems s.r.l.; Reggio Emilia, Italy; device can recognize volatile compounds through a tailormade array of different materials. The results can be shown on a PCA that is directly generated by the instruments and can be used to manage the productive process through an IoT integrated system. Testing different beer typology through electrochemical sensors allows for the validation of this new approach for diacetyl evaluation. The results have shown an excellent ability to detect diacetyl in different beer samples, perfectly discriminating among different concentrations.

Real Time Monitoring of Wine Vinegar Supply Chain through MOX Sensors.

Vinegar is a fermented product that is appreciated world-wide. It can be obtained from different kinds of matrices. Specifically, it is a solution of acetic acid produced by a two stage fermentation process. The first is an alcoholic fermentation, where the sugars are converted in ethanol and lower metabolites by the yeast action, generally Saccharomyces cerevisiae. This was performed through a technique that is expanding more and more, the so-called “pied de cuve”. The second step is an acetic fermentation where acetic acid bacteria (AAB) action causes the conversion of ethanol into acetic acid. Overall, the aim of this research is to follow wine vinegar production step by step through the volatiloma analysis by metal oxide semiconductor MOX sensors developed by Nano Sensor Systems S.r.l. This work is based on wine vinegar monitored from the grape must to the formed vinegar. The monitoring lasted 4 months and the analyses were carried out with a new generation of Electronic Nose (EN) engineered by Nano Sensor Systems S.r.l., called Small Sensor Systems Plus (S3+), equipped with an array of six gas MOX sensors with different sensing layers each. In particular, real-time monitoring made it possible to follow and to differentiate each step of the vinegar production. The principal component analysis (PCA) method was the statistical multivariate analysis utilized to process the dataset obtained from the sensors. A closer look to PCA graphs affirms how the sensors were able to cluster the production steps in a chronologically correct manner.

Hybrid nanoassembly with two-tier host-guest architecture and regioselective enrichment capacity for repetitive SERS detection

Due to the challenge of controlling analyte-particle and particle-particle distances in the SERS detection matrix, the most promising nanosensor systems still suffer from difficulties in increasing the sensing stability and repeatability. Herein, a host-guest assembly strategy was developed to build two-tier nanoarchitecture based SERS device for a highly repetitive detection system. Specifically, gold nanoparticles were installed on the outer surface of mesoporous polydopamine nanoparticles and modified with a self-assembled monolayer of 11-Mercapto-1-undecanol to drive the regioselective enrichment of analytes in the mesopores. Subsequently, the host-guest nanosensor particles were assembled into a uniform coffee ring pattern (~4 mm in inner diameter and 500 µm in width) on the surface of a porous host (polyvinylidene fluoride film with a pore size of 0.45 µm) through fast particle packing (20 s) driven by water infiltration in membrane pores. Finally, the sensing system achieved highly repeatable (RSD 3.1%−3.4%) analysis of organic dyes (limit-of-detection, LOD 24.1–59.6 fM) and miRNA (LOD 308.5 fM). The nanoassembly platform with distance constraint and enrichment effects is expected to pave a new avenue for interfacial engineering strategies of SERS sensors.

Reference materials for optic nanosensor systems: reduced glutathione and chloramphenicol

The research provides enterprise reference material (ERM) development approach for nanosensor system on the basis of dynamic light scattering and fluorescence for qualitative and quantitative determination of nutrition pollutant - chloramphenicol antibiotic (laevomycetin), as well as marker of ischaemic stroke and a number of other diseases - reduced glutathione.ERM candidate materials were chosen chloramphenicol and reduced glutathione. The attestation procedure based on calculating-experimental approach by preparation procedure was used to determine the certified value of ERM. During the tests there were determined metrological characteristics of reference material. The certified value of ERM for reduced glutathione mass fraction is 98,5 %, the expanded uncertainty of certified value with coverage factor k=2 is ± 0,3 %. The certified value of ERM for chloramphenicol mass concentration is 10,0 g/dm3, the expanded uncertainty of certified value with coverage factor k = 2 is ± 4,0 %.The implementation of the developed ERMs showed their appropriateness for optic nanosensor systems calibration on the base of dynamic light scattering and fluorescence.We suppose that the developed enterprise reference materials further may be certified as CRM (certified reference material) and used for verification, calibration and graduation of compact detection devices of the «point of care diagnostics» type under development, which are intended for express analysis on the sampling site directly.

Colorimetric optical nanosensors for trace explosive detection using metal nanoparticles: advances, pitfalls, and future perspective

Warfare threats and acts of terror are challenging situations encountered by defense agencies across the globe and are of growing concern to the general public, and security-minded policy makers. Detecting ultra-low quantities of explosive compounds in remote locations or under harsh conditions for anti-terror purposes as well as the environmental monitoring of residual or discarded explosives in soil, remains a major challenge. The use of metal nanoparticles (NPs) for trace explosive detection has drawn considerable interest in recent years. For nano-based explosive sensor devices to meet real-life operational demands, analytical parameters such as, long-shelf life, stability under harsh conditions, ease-of-use, high sensitivity, excellent selectivity, and rapid signal response must be met. Generally, the analytical performance of colorimetric-based nanosensor systems is strongly dependent on the surface properties of the nanomaterial used in the colorimetric assay. The size and shape properties of metal NPs, surface functionalisation efficiency, and assay fabrication methods, are factors that influence the efficacy of colorimetric explosive nanosensor systems. This review reports on the design and analytical performances of colorimetric explosive sensor systems using metal NPs as optical signal transducers. The challenges of trace explosive detection, advances in metal NP colorimetric explosive design, limitations of each methods, and possible strategies to mitigate the problems are discussed.

(Keynote) Wireless Wearable and Implantable Monitoring and Therapeutic Systems for Cardiac and Neurological Disorders

Wearable nanosensor systems in the form of smart clothing, equipped with wireless communication technology, provides real-time medical data to health professionals for early diagnosis, planning therapeutic intervention, and following up on the effect of planned therapy. Techniques, such as electrocardiography (ECG), electroencephalography (EEG), electrooculography (EOG), electromyography (EMG) and electrical impedance tomography, are relevant to POC for cardiovascular disease, neurological disorders, cancer, and stroke. Intelligent wearable sensor systems with simple installation, minimal maintenance, and user involvement can be the best method for ubiquitous health monitoring. We have been working with a printable organic semiconductor and thin film transistor and have fabricated and tested various biosensors that can measure important physiological signs before and after surgery. Integrated into "smart" fabrics - garments with wireless technology – and independent e-bandaid sensors, nanosensors in tattoos and socks, minimally invasive implantable devices, the sensor systems will be able to monitor a patient's condition in real time and thus provide point-of-care diagnostics to health-care professionals and greater freedom for patients. This talk addresses this emerging area with selected videos of subjects for real time measurements and control cardiac and neurological diseases. Combined with state-of-the-art embedded wireless network devices to communicate with smartphone, laptop or directly to remote server through mobile network (GSM,4G-LTE,GPRS), they can function as wearable wireless health-diagnostic systems that are more intuitive to use.

Mathematical Modeling of Nanosensor Systems Based on Dynamic Light Scattering

A mathematical model describing optical nanosensors, the principle of action of which is based on an increase in the hydrodynamic diameters of functionalized nanoparticles (conjugates) under the influence of an analyte, is constructed. The formation of shells from analyte molecules around conjugates and the aggregation of conjugates to dimers at the expense of “bridges” represented by analyte molecules are considered. Antibodies capable of association with antibody footprints (epitopes) on analyte molecules are considered receptors, which are used for the functionalization of nanoparticles. The input parameters of the model are the sizes and concentrations of conjugates, kinetic constants of association and dissociation of receptors with epitopes, number of receptors per conjugate, and the concentration of the analyte. The model makes it possible to estimate the ranges of defined concentrations, as well as detect the limits during the development of nanosensors for specific analytes and optimizing parameters of these sensors, including the required incubation time for a mixture of conjugates with an analyte.

Al‐Doped ZnO Nanowires by Electrochemical Deposition for Selective VOC Nanosensor and Nanophotodetector

Nanomaterials for new nanosensor systems with selective detection of hazardous volatile organic compounds (VOCs) vapors are of great demand nowadays. In this paper, the use in nanosensors of electrochemically deposited (ECD) Al‐doped ZnO (ZnO:Al) nanowires (NWs) is reported. The NWs are characterized by micro‐Raman and optical measurements. Individual ZnO and ZnO:Al NWs are integrated into nanosensor devices for room temperature UV and gas sensing. It is shown that, compared to undoped ZnO NW with irreversible response, the doped ZnO:Al NWs have faster response (≈5 s) and recovery (≈55 s), as well as enhanced UV response (≈4.8, about 2 times higher). The room temperature gas sensing investigations demonstrate that an individual ZnO:Al NW can detect volatile organic compounds (VOCs) vapors such as 2‐propanol, n‐butanol and ethanol at room temperature with a relatively fast response time of ≈10 s and a reversible signal (the recovery time being 30–40 s). This shows the possibility to use it with further development as indoor air quality monitor.

(Invited) Flexible Piezo-, Tribo-Electric Energy Harvesting Devices for Self-Powered Nanosensor Systems

Flexible devices have been drawn a great attention as next-generation electronic devices. Especially for flexible and wearable system, the challenge to achieve such systems are the development of functional and flexible new materials and unique integration method of conventional devices into flexible ones including high performances. Nevertheless, such nanosystem also requires a power source to make the entire package small, sustainable and even long lasting. In this regards, harvesting energy from the environment is a choice for powering nanosystems. As for the goal, it is desired to explore flexible and wearable devices for scavenging energy around our surroundings, thus it can supply the power to nanosensor system without consuming much battery or to supporting battery life. Here, we will present some approaches for converting mechanical energy into electric energy using piezoelectric or triboelectric effects. This technology may make it possible to harvest energy from certain mechanical movements or human activity. Moreover, self-powered nano-sensor systems have been fabricated by combining the energy harvesting technology which ensures its compatibility and perspective. The presentation will be continuously dedicated to recent developments and improvements of energy harvesting technology towards self-powered nano-systems such as mobile electronics and wearable healthcare.

Heterogeneous time-resolved electrochemiluminoimmunoassay of thyroid stimulating hormone with magnetic beads at oxide-covered aluminum electrode

The heterogeneous immunoassay of thyroid stimulating hormone (TSH) was detected by the time-resolved cathodic electrochemiluminescence immunoassay (tr-CECLIA) method using magnetic beads as a mobile support. The magnetic beads coated with sandwich type TSH immunoassay were captured with a magnet for washing and detection processes. The time-resolved cathodic electrochemiluminescence (tr-CECL) signal of Tb(III) chelate label was generated by cathodic pulse polarization in the aluminum working electrode and platinum counter electrode system. The detection method causes injection of high energy electrons into the aqueous solution near the aluminum electrode and creates rigid simultaneous oxidative and reductive conditions that excitate the Tb(III) chelate used as a label luminophore in the heterogeneous sandwich type immunoassay of TSH in the surface of the magnetic beads. The limit of detection of the method was about 50mIUL−1. The precision of it was noticed to be good; the coefficient variation percentage was realized to be lower than 10 %. Unfortunately the limit of detection is not good enough for determination of analyte levels of very low concentrations for instance TSH in body fluids. The possible application areas of the method are in highly sophisticated micro or nano fluidic detection and sensor systems where the aspiration level of the analyte detection limit is not very high and the mobility and manageability and the large surface area of the magnetic beads can be utilized efficiently in separating, washing, moving, coating and detecting processes. In the case of tr-CECLIA the presented method makes possible to use multipurpose working electrodes instead of disposable ones.

Data Storage and Retrieval on Nanoparticles

Recent advances at developing nanoscale electronic devices lead us to believe that in the near term the nanomemories in the form of nanodisks and nanotubes will replace existing storage systems and will be integrated into the implementation of nanocomputers and complex nanosensor systems. In this work the issue of recording and reading data using the magnetic vortex of nanodisks is addressed. By using the polarity and chirality properties of the magnetic vortex it may be possible to store information in binary or nonbinary form. Nevertheless, as in any storage system, information can be altered by the presence of noise, and therefore it is necessary to incorporate error control coding. In this regard, here we analyse the behaviour of the proposed system using Turbo coding and Low Density Parity Check (LDPC) coding in order to correct errors in the writing and reading process in nanoparticles. Simulations were performed for the binary case considering the polarity of the magnetic vortex to store information. This, because it appears to be the first workable level in the short term, before reaching practical implementations involving the simultaneous control of polarity and chirality to store non-binary data.

Plenary Talk--Nanosensor Systems. e-Bra, e-Band and Wireless Electronics for Monitoring and Control of Cardiovascular Diseases and Neurological Disorders

not Available.

Tin oxide nanosensors for highly sensitive toxic gas detection and their 3D system integration

We present nanosensors based on ultrathin SnO2 films, which are very sensitive to the highly toxic gases SO2 and H2S. The SnO2-sensing films are fabricated by a spray pyrolysis process on Si substrates with a thickness of 50nm. The sensor resistance is decreased in the presence of the toxic gases. Exposure to 50ppm SO2 leads to a sensor resistance drop of ∼40% whereas a H2S gas concentration of only 2.5ppm decreases the resistance by ∼85%, which demonstrates the extraordinary sensitivity of the nanosensors. With respect to further system integration a CMOS technology based micro-hotplate containing heating element and sensing layer has been simulated. Preliminary results show that the micro-hotplates can provide operating temperatures of 400°C with a power consumption of less than 5mW. A concept for 3D system integration of the nanosensor chip and a CMOS chip based on Through-Silicon-Via (TSV) technology is proposed as potential roadmap towards smart nanosensor systems for daily life applications.

Nanobiosensors: probing the sanctuary of individual living cells.

Recently, nanotechnology has been revolutionizing important areas in molecular biology, especially diagnostics and therapy at the molecular and cellular level. The combination of nanotechnology, biology, and photonics opens the possibility of detecting and manipulating atoms and molecules using nanodevices, which have the potential for a wide variety of medical uses at the cellular level. The nanoprobes were fabricated with optical fibers pulled down to tips with distal ends having sizes of approximately 30-50 nm. The nanoscale size of this new class of sensors, allows for measurements in the smallest of environments. One such environment that has evoked a great deal of interest is that of individual cells. Using these nanobiosensors, it has become possible to probe individual chemical species in specific locations throughout a cell. This article provides an overview of the principle, development, and applications of optical nanosensor systems for in vivo bioanalysis at the single-cell level. The fiberoptics nanoprobes were covalently bound with antibodies that are selective to target analyte molecules. Excitation light is launched into the fiber and the resulting evanescent field at the tip of the fiber is used to excite target molecules bound to the antibody molecules. The fluorescence emission from the analyte molecules is then collected via a microscope. The usefulness and potential of this nanotechnology-based biosensor systems in biological research and applications in single-cell analysis are discussed.