Heavy metal/toxins detection using electronic tongues

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOThe growing concern for sustainability and environmental preservation has increased the demand for reliable, fast response, and low-cost devices to monitor the existence of heavy metals and toxins in water resources. An electronic tongue (e-tongue) is a multisensory array mostly based on electroanalytical methods and multivariate statistical techniques to facilitate information visualization in a qualitative and/or quantitative way. E-tongues are promising analytical devices having simple operation, fast response, low cost, easy integration with other systems (microfluidic, optical, etc) to enable miniaturization and provide a high sensitivity for measurements in complex liquid media, providing an interesting alternative to address many of the existing environmental monitoring challenges, specifically relevant emerging pollutants such as heavy metals and toxins.73119FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOSem informaçã

State-of-the-Art of (Bio)Chemical Sensor Developments in Analytical Spanish Groups

(Bio)chemical sensors are one of the most exciting fields in analytical chemistry today. The development of these analytical devices simplifies and miniaturizes the whole analytical process. Although the initial expectation of the massive incorporation of sensors in routine analytical work has been truncated to some extent, in many other cases analytical methods based on sensor technology have solved important analytical problems. Many research groups are working in this field world-wide, reporting interesting results so far. Modestly, Spanish researchers have contributed to these recent developments. In this review, we summarize the more representative achievements carried out for these groups. They cover a wide variety of sensors, including optical, electrochemical, piezoelectric or electro-mechanical devices, used for laboratory or field analyses. The capabilities to be used in different applied areas are also critically discussed

Recent advances in chemical sensors for soil analysis: a review

The continuously rising interest in chemical sensors' applications in environmental monitoring, for soil analysis in particular, is owed to the sufficient sensitivity and selectivity of these analytical devices, their low costs, their simple measurement setups, and the possibility to perform online and in-field analyses with them. In this review the recent advances in chemical sensors for soil analysis are summarized. The working principles of chemical sensors involved in soil analysis; their benefits and drawbacks; and select applications of both the single selective sensors and multisensor systems for assessments of main plant nutrition components, pollutants, and other important soil parameters (pH, moisture content, salinity, exhaled gases, etc.) of the past two decades with a focus on the last 5 years (from 2017 to 2021) are overviewed

Desenvolupament de sensors i llengües electròniques voltamperomètriques per a la determinació d’ions metàl·lics en mostres d’interès ambientals

[cat] La problemàtica mediambiental associada a la contaminació per ions metàl·lics és mundialment coneguda. En les últimes dècades hi ha hagut un enduriment de la legislació associada a aquests contaminants que ha permès disminuir les seves emissions al medi ambient però, degut a la seva elevada persistència i al seu caràcter no biodegradable, les concentracions dels ions metàl·lics en mostres mediambientals són encara preocupants. Actualment, tot i que existeixen diverses tècniques analítiques per a la determinació d’ions metàl·lics, encara és necessari el desenvolupament de noves metodologies analítiques que permetin determinar-los on-site i a nivell traça. En aquest sentit, les tècniques voltamperomètriques de redissolució són una bona opció ja que són tècniques sensibles i reproduïbles que proporcionen anàlisis ràpides sense requerir instrumentació voluminosa o excessivament costosa. A més, el caràcter portàtil d’aquestes tècniques s’ha vist afavorit amb la introducció dels elèctrodes serigrafiats, que són dispositius compactes, miniaturitzats, versàtils i que es poden produir en massa. Un dels avantatges que proporcionen els elèctrodes serigrafiats és la possibilitat de modificar el seu elèctrode de treball per tal de millorar la seva sensibilitat i selectivitat o permetre treballar a diferents condicions experimentals. En aquest sentit, una primera part d’aquesta tesi doctoral s’ha centrat en el desenvolupament de nous elèctrodes serigrafiats voltamperomètrics per a la determinació d’ions metàl·lics a nivell traça en mostres mediambientals. Concretament, s’han estudiat diferents estratègies de modificació com la modificació química, la formació de pel·lícules metàl·liques i l’ús de diversos nanomaterials (nanopartícules metàl·liques, nanoal·lòtrops de carboni i silici porós). Per a cada estratègia s’han estudiat diferents aspectes del procés de modificació i s’ha avaluat l’aplicabilitat del sensor que proporciona millors resultats en mostres reals. Sovint però, en l’anàlisi de mostres reals trobem mescles complexes on els ions metàl·lics s’interfereixen entre si o donen lloc a pics solapats. En aquests casos l’ús d’un sol sensor no permet determinar correctament la concentració dels diferents ions i cal recórrer a altres estratègies d’anàlisi més sofisticades. Aquest és el cas de les llengües voltamperomètriques, on es combinen diversos sensors no específics amb un tractament de dades multivariant. Així, la segona part d’aquesta tesi doctoral s’ha centrat en el desenvolupament de llengües voltamperomètriques per a l’anàlisi de mostres complexes d’ions metàl·lics. Concretament s’han estudiat el sistema Tl(I) i In(III) i el sistema Cd(II), Pb(II), Tl(I) i Bi(III) en presència de Zn(II) i In(III), que es caracteritzen, respectivament, per la presència de dos metalls que donen lloc a senyals fortament solapats i per la presència d’un elevat nombre de metalls. Concretament, s’ha estudiat la selecció dels sensors que componen la llengua voltamperomètrica, la seva disposició i el disseny experimental. Un altre aspecte crucial en el desenvolupament de les llengües voltamperomètriques és el tractament de dades. Així, en la segona part d’aquesta tesi doctoral també s’ha fet èmfasi en aquest tema, on s’han estudiat diversos pretractaments i s’han construït diversos models quimiomètrics basats en la regressió per mínims quadrats parcials (PLS). A més, s’han estudiat també dos sistemes de calibratge multivariant, el calibratge multivariant extern i l’addició estàndard multivariant, per a la qual s’ha desenvolupat una nova estratègia basada en l’ús de PLS i la simulació del blanc de la mostra a partir de l’omissió de l’etapa de preconcentració de la mesura voltamperomètrica. Aquest segon mètode de calibratge proporciona prediccions més acurades per a mostres amb un fort efecte matriu. Els resultats obtinguts a partir dels estudis realitzats al llarg d’aquesta tesi doctoral han donat lloc a 12 articles, 9 d’ells referents a la part de desenvolupament de sensors voltamperomètrics i 3 referents al desenvolupament de llengües voltamperomètriques.[eng] On-site monitoring of metal ions at trace levels is crucial for safety and environmental reasons. In this sense, stripping voltammetry is a good option due to its high sensitivity and reproducibility and the fact that it provides fast analysis with relatively low cost and portable equipment. These last features are further enhanced by the coupling of stripping voltammetry with screen-printed electrodes, which are compact, miniaturized and versatile devices that can be mass-produced in a reproducible manner. A first part of this PhD thesis has focused on the development of new screen-printed voltammetric sensors for the determination of metal ions at trace levels in environmental samples. Particularly, several modification strategies (chemical modification, metal films and nanomaterials) have been studied. For each strategy, some aspects of the modification process were evaluated and their applicability to real samples was tested for the sensor that provided better results. Frequently though, the analysis of real samples involves complex mixtures where metal ions interact with each other or give rise to highly overlapped peaks. In these scenarios, it is necessary to resort to more sophisticated analytical strategies like voltammetric electronic tongues. Thus, the second part of this PhD thesis has focused on the development of voltammetric tongues for the analysis of complex mixtures of metal ions. In particular, two systems have been studied: Tl(I) and In(III), two metals that give rise to highly overlapped peaks, and Cd(II), Pb(II), Tl(I) and Bi(III) in the presence of Zn(II) and In(III). In both cases, several studies involving the selection of sensors, their arrangement and the experimental design were performed. The second part of this PhD thesis has also focused on data treatment, a key aspect in the development of voltammetric tongues. Two multivariate calibration systems were studied, multivariate external calibration and multivariate standard addition, for which a new strategy based on PLS and the simulation of a blank signal by skipping the deposition step of stripping voltammetry was developed. The results achieved throughout this PhD thesis have resulted in 12 articles, 9 related to the development of voltammetric sensors and 3 related to the development of voltammetric electronic tongues

The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry

The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry was held on 1–15 July 2021. The scope of this online conference was to gather experts that are well-known worldwide who are currently working in chemical sensor technologies and to provide an online forum for the presention and discussion of new results. Throughout this event, topics of interest included, but were not limited to, the following: electrochemical devices and sensors; optical chemical sensors; mass-sensitive sensors; materials for chemical sensing; nano- and micro-technologies for sensing; chemical assays and validation; chemical sensor applications; analytical methods; gas sensors and apparatuses; electronic noses; electronic tongues; microfluidic devices; lab-on-a-chip; single-molecule sensing; nanosensors; and medico-diagnostic testing

Advance in Energy Harvesters/Nanogenerators and Self-Powered Sensors

This reprint is a collection of the Special Issue "Advance in Energy Harvesters/Nanogenerators and Self-Powered Sensors" published in Nanomaterials, which includes one editorial, six novel research articles and four review articles, showcasing the very recent advances in energy-harvesting and self-powered sensing technologies. With its broad coverage of innovations in transducing/sensing mechanisms, material and structural designs, system integration and applications, as well as the timely reviews of the progress in energy harvesting and self-powered sensing technologies, this reprint could give readers an excellent overview of the challenges, opportunities, advancements and development trends of this rapidly evolving field

Qualitative Recognition of Typical Loads in Low-Speed Rotor System

While the load variations within the low speed rotor systems affect the operating conditions and mechanical properties, they may also provide information on machine faults. Therefore, load recognition is of great significance in operational monitoring for detecting early warning signs of failure and diagnosing faults. In this paper, five types of typical loads in a low-speed rotor system are qualitatively analyzed. Moreover, a method is presented based on the vibration signals from a low-speed rotor system using the ensemble empirical mode decomposition (EEMD), energy feature extraction, and backpropagation neural network (BPNN). A low-speed rotor test bench was designed and manufactured for load recognition and an experiment was set up based on certain load characteristics. Loading tests for five representative categories were conducted and various vibration signals were collected simultaneously. The EEMD was shown to eliminate the mode mixing seen in traditional EMD, which resulted in a clear decomposition of the signal. Finally, the characteristics were imported into a BPNN after energy feature extraction, and the different types of load were accurately recognized. Comparing the experimental results to existing data, a total recognition rate of 92.38% was achieved, demonstrating that the proposed method is both reliable and efficient

New analytical applications of gold nanoparticles

The work includes improvements of surface technology, new analytical applications of metallic nanoparticles and optimization of technological steps for production of different types of metallic nanoparticles in discrete and continuous modes. The technology of LbL deposition was optimized and applied for immobilization of metallic nanoparticles. SPR detection was used for the determination of optimal deposition conditions and on-line monitoring of the deposition process. Simple approach for automation of LbL deposition allowing one to deposit up to hundreds of layers was developed. The technology was proved by electrochemical analysis for deposition of electrochemically active polymers. A new diffusion based semi-quantitative assay for detection of sugars was suggested. Electrochemical oxidation of glucose and dopamine on electrodes modified with gold nanoparticles was studied. Conditions for electrochemical analysis of these substances in the presence of typical natural interferents were evaluated. A combination of voltammetry and impedance spectroscopy was used to demonstrate a formation of insulating layer on gold surface, this resulted in explanation of anomalous shape of voltammetric curves. A combination of electrochemical and SPR measurements demonstrated directly a formation of an insulating layer on the electrode surface and was used for optimization of the assay conditions. The results indicate a possibility to develop an enzyme free sensors for glucose and dopamine. It was discovered that gold nanoparticles are effective nucleating agents for protein crystallization. Nanoparticles induce protein crystallization at lower supersaturation and increase the number of protein crystals formed at higher supersaturation. The fact that this technology works with so different proteins as lysozyme and ferritin allows one to suggest that it may be also applied for many other proteins including the ones which are reluctant to crystallization by known technologies. Irreversible freezing indicators based on gold nanoparticles were developed. The filling suspension containing nanoparticles, nucleation and stabilization agents were optimized in sense of stability and irreversibility of color changes. A large scale production of this indicator will be started in spring 2008

Applications and Experiences of Quality Control

The rich palette of topics set out in this book provides a sufficiently broad overview of the developments in the field of quality control. By providing detailed information on various aspects of quality control, this book can serve as a basis for starting interdisciplinary cooperation, which has increasingly become an integral part of scientific and applied research