NANOPARTICLE BASED GAS-SENSING ARRAY FOR PESTICIDE DETECTION_data.rar

Data obtained during measurement/characterisation of multiple sensor, as seen and analysed in the paper: "NANOPARTICLE BASED GAS-SENSING ARRAY FOR PESTICIDE DETECTION". Data are in txt form and can be opened and processed using any related software (e.g. origin, excel etc.

Thin Film Protected Flexible Nanoparticle Strain Sensors: Experiments and Modeling

In this work, the working performance of Platinum (Pt), solvent-free nanoparticle (NP)-based strain sensors made on a flexible substrate has been studied. First, a new model has been developed in order to explain sensor behaviour under strain in a more effective manner than what has been previously reported. The proposed model also highlights the difference between sensors based on solvent-free and solvent-based NPs. As a second step, the ability of atomic layer deposition (ALD) developed Al2O3 (alumina) thin films to act as protective coatings against humidity while in adverse conditions (i.e., variations in relative humidity and repeated mechanical stress) has been evaluated. Two different alumina thicknesses (5 and 11 nm) have been tested and their effect on protection against humidity is studied by monitoring sensor resistance. Even in the case of adverse working conditions and for increased mechanical strain (up to 1.2%), it is found that an alumina layer of 11 nm provides sufficient sensor protection, while the proposed model remains valid. This certifies the appropriateness of the proposed strain-sensing technology for demanding applications, such as e-skin and pressure or flow sensing, as well as the possibility of developing a comprehensive computational tool for NP-based devices

Nanoparticles Synthesised in the Gas-Phase and Their Applications in Sensors: A Review

This article aims to provide a comprehensive review of recent advances in the use of gas-phase synthesized nanoparticles in the field of sensing technology. Since there are numerous and diverse reviews that already cover the subject extensively, this review focuses predominantly but not exclusively on gas-phase synthesized metallic nanoparticles and their most prominent sensing-applications. After a brief overview on the main uses of nanoparticles in science and technology, as well as a description of the dominant fabrication methods, the review discusses their incorporation in strain-sensing, chemical sensing and bio-sensing as well as a few other sensing-applications. The review highlights the inherent advantages of nanoparticles, as well as how they combine with flexible gas-phase synthesis processes

Vibration Sensors on Flexible Substrates Based on Nanoparticle Films Grown by Physical Vapor Deposition

Flexible electronics have gained a lot of attention in recent years due to their compatibility with soft robotics, artificial arms, and many other applications. Meanwhile, the detection of acoustic frequencies is a very useful tool for applications ranging from voice recognition to machine condition monitoring. In this work, the dynamic response of Pt nanoparticles (Pt NPs)-based strain sensors on flexible substrates is investigated. the nanoparticles were grown in a vacuum by magnetron-sputtering inert-gas condensation. Nanoparticle sensors made on cracked alumina deposited by atomic layer deposition on the flexible substrate and reference nanoparticle sensors, without the alumina layer, were first characterized by their response to strain. The sensors were then characterized by their dynamic response to acoustic frequency vibrations between 20 Hz and 6250 Hz. The results show that alumina sensors outperformed the reference sensors in terms of voltage amplitude. Sensors on the alumina layer could accurately detect frequencies up to 6250 Hz, compared with the reference sensors, which were sensitive to frequencies up to 4250 Hz, while they could distinguish between two neighboring frequencies with a difference of no more than 2 Hz

Self assembly of nanoparticles and their application in chemical sensing

189 σ.Στην παρούσα εργασία επιχειρείται η χρήση αυτό-οργανωμένων νανοσωματιδίων για την κατασκευή αισθητήρων κυρίως αερίων χημικών ουσιών. Τα νανοσωματίδια που χρησιμοποιούνται στις εφαρμογές αισθητήρων είναι μεταλλικά ενώ αυτό-οργανώνονται σε υποστρώματα πυριτίου ή πολυιμιδίου μέσω της εκτύπωσης τους από έναν εκτυπωτή ψεκασμού μελάνης ή κατευθείαν μετά την παραγωγή τους από ένα σύστημα ιοντοβολής υπό κενό. Κύριο ενδιαφέρον της εργασίας αποτελεί η ανίχνευση εξωτερικών ερεθισμάτων μέσω μεταβολών στην αγωγιμότητα/ηλεκτρική αντίσταση των αισθητήρων Η εργασία διαρθρώνεται σε δύο κυρίως μέρη, το εισαγωγικό και το πειραματικό. Στο εισαγωγικό μέρος (κεφάλαιο 1) περιγράφονται οι επιπτώσεις της μετάβασης στην νανοκλίμακα ενώ παράλληλα αναλύονται οι σημερινές τάσεις όσον αφορά την χρήση νανοσωματιδίων σε εφαρμογές χημικών αισθητήρων. Ιδιαίτερη έμφαση δίνεται στην περιγραφή των μηχανισμών αγωγιμότητας που διέπουν τα φαινόμενα μεταφοράς φορτίου μεταξύ νανοσωματιδίων μια και αποτελούν την βάση του μηχανισμού ανίχνευσης του αισθητήρα, αλλά και στην ταυτοποίηση των μηχανισμών αγωγιμότητας για τους αισθητήρες που περιγράφονται στο πειραματικό κομμάτι. Το εισαγωγικό κομμάτι της εργασίας κλείνει με την περιγραφή των κύριων πειραματικών διαδικασιών/τεχνικών για την κατασκευή των αισθητήρων. Το πειραματικό μέρος της εργασίας χωρίζεται σε τρία κύρια μέρη. Στο πρώτο μέρος (κεφάλαιο 2) περιγράφονται και αξιολογούνται χημικοί αισθητήρες αερίων που παρασκευάστηκαν εξολοκλήρου μέσω εκτύπωσης τόσο των νανοσωματιδίων όσο και του πολυμερικού στρώματος ανίχνευσης. Για τους χημικούς αισθητήρες του δεύτερου μέρους (κεφάλαιο 3) τα νανοσωματίδια παράγονται και εναποτίθενται μέσω ενός συστήματος ιοντοβολής ενώ τα υποστρώματα εναπόθεσης είναι είτε υποστρώματα πυριτίου ή πολυιμιδίου. Τέλος στο τρίτο κομμάτι (κεφάλαιο 4) παρατίθενται επιπλέον εφαρμογές αισθητήρων από την ίδια ουσιαστικά πλατφόρμα ανίχνευσης. Πιο συγκεκριμένα διατάξεις μεταλλικών νανοσωματιδίων ανιχνεύουν παραμόρφωση υποστρώματος αλλά και βιολογικά γεγονότα όπως την υβριδοποίηση αλυσίδων DNA. Η εργασία ολοκληρώνεται με κάποια γενικά συμπεράσματα αλλά και προτάσεις για μελλοντικές εργασίες ενώ παρατίθεται πλήρης λίστα δημοσιεύσεων.In the present PhD thesis the use of self-organized nanoparticles, mainly for chemical sensing applications, is explored. The nanoparticles used throughout the thesis are metallic and are deposited on silicon or polyimide substrates by means of ink-jet printing or inside a vacuum sputtering system. The main interest of this thesis is the detection of an agent by conductivity/resistance changes in the sensors. The thesis is organized in two main parts, the introductory part and the experimental part. In the first part (chapter 1) the ramifications of using nano-sized materials and the current trends in the use of nano-materials for chemical sensing applications are discussed. Particular emphasis is given in the presentation of the mechanisms governing charge transport phenomena through nanoparticles, being the ‘’backbone’’ of the sensor, and on the identification of the transport mechanisms for the sensors described in the experimental part. The first part closes with a brief description of the main experimental/fabrication techniques used for the fabrication of the sensors. The experimental part of the thesis is consisted of three sub-parts. The first sub-part (chapter 2) discusses the fabrication and evaluation of chemical gas sensors fabricated entirely by means of ink-jet printing (for both nanoparticle and polymer layer). The second one (chapter 3) focuses on sensors in which the nanoparticle layer is produced by means of DC sputtering while the sensor’s substrates can either be silicon or polyimide. Finally in the third part (chapter 4) additional sensing applications, based on the same nanoparticle sensing platform, are given. To be more specific nanoparticle strain-sensing and bio sensing applications are being discussed. The thesis is completed by some general remarks/conclusions and by proposing future work prospects.Ευάγγελος Ν. Σκοτάδη

Overcoming the response instability of MoS2 humidity sensors by hydrochloric acid surface treatment

The synthesis of MoS2 with chemical vapor deposition (CVD) using sodium molybdate (Na2MoO4) as the Mo precursor produces a big number of large flakes (∼100-300 μm) compared to other CVD methods that use different precursors. In this work, humidity sensors based on MoS2 are developed, whereby MoS2 is grown using this Mo precursor in an aqueous solution form. The final devices exhibit a response-switching during operation under high (>50%) relative humidity conditions, due to the presence of Na2MoO4 residues on their surface. By decreasing the concentration of the aqueous Mo precursor during the CVD process we partially diminish the switching effect, as the Na2MoO4 residue is reduced To completely overcome this issue, we present a post-fabrication surface treatment using hydrochloric acid that removes the Na2MoO4 residue from the devices' surface. Rinsing the devices with an HCl solution results in the elimination of the response-switching effect and the sensors demonstrate a constant positive response from the initial operation steps

Identification of Two Commercial Pesticides by a Nanoparticle Gas-Sensing Array

This study presents the experimental testing of a gas-sensing array, for the detection of two commercially available pesticides (i.e., Chloract 48 EC and Nimrod), towards its eventual use along a commercial smart-farming system. The array is comprised of four distinctive sensing devices based on nanoparticles, each functionalized with a different gas-absorbing polymeric layer. As discussed herein, the sensing array is able to identify as well as quantify three gas-analytes, two pesticide solutions, and relative humidity, which acts as a reference analyte. All of the evaluation experiments were conducted in close to real-life conditions; specifically, the sensors response towards the three analytes was tested in three relative humidity backgrounds while the effect of temperature was also considered. The unique response patterns generated after the exposure of the sensing-array to the two gas-analytes were analyzed using the common statistical analysis tool Principal Component Analysis (PCA). The sensing array, being compact, low-cost, and highly sensitive, can be easily integrated with pre-existing crop-monitoring solutions. Given that there are limited reports for effective pesticide gas-sensing solutions, the proposed gas-sensing technology would significantly upgrade the added-value of the integrated system, providing it with unique advantages

Breath Analysis: A Promising Tool for Disease Diagnosis—The Role of Sensors

Early-stage disease diagnosis is of particular importance for effective patient identification as well as their treatment. Lack of patient compliance for the existing diagnostic methods, however, limits prompt diagnosis, rendering the development of non-invasive diagnostic tools mandatory. One of the most promising non-invasive diagnostic methods that has also attracted great research interest during the last years is breath analysis; the method detects gas-analytes such as exhaled volatile organic compounds (VOCs) and inorganic gases that are considered to be important biomarkers for various disease-types. The diagnostic ability of gas-pattern detection using analytical techniques and especially sensors has been widely discussed in the literature; however, the incorporation of novel nanomaterials in sensor-development has also proved to enhance sensor performance, for both selective and cross-reactive applications. The aim of the first part of this review is to provide an up-to-date overview of the main categories of sensors studied for disease diagnosis applications via the detection of exhaled gas-analytes and to highlight the role of nanomaterials. The second and most novel part of this review concentrates on the remarkable applicability of breath analysis in differential diagnosis, phenotyping, and the staging of several disease-types, which are currently amongst the most pressing challenges in the field

Integrated Plastic Microfluidic Device for Heavy Metal Ion Detection

The presence of heavy metal ions in soil, air and water constitutes an important global environmental threat, as these ions accumulate throughout the food chain, contributing to the rise of chronic diseases, including, amongst others, cancer and kidney failure. To date, many efforts have been made for their detection, but there is still a need for the development of sensitive, low-cost, and portable devices able to conduct on-site detection of heavy metal ions. In this work, we combine microfluidic technology and electrochemical sensing in a plastic chip for the selective detection of heavy metal ions utilizing DNAzymes immobilized in between platinum nanoparticles (PtNPs), demonstrating a reliable portable solution for water pollution monitoring. For the realization of the microfluidic-based heavy metal ion detection device, a fast and easy-to-implement fabrication method based on the photolithography of dry photosensitive layers is proposed. As a proof of concept, we demonstrate the detection of Pb2+ ions using the prototype microfluidic device