This work presents a graphene-based magnetoelastic (ME) biosensor platform for wireless antibody detection via magnetoelastic resonance. Graphene was chosen for its biocompatibility and high surface area, enabling efficient antigen adsorption, validated by techniques such as EDX, AFM, and micro-Raman. Changes in Raman bands (a similar to 10 cm-1 shift in the 2D band and an increase in the I D/I G ratio from 0.03 to 0.60) indicate non-covalent interactions and suggest enhanced surface coverage with 100 & micro;g of N-nucleocapsid phosphoprotein. Tests using human plasma (10 RT-PCR-positive and 10 negative samples) demonstrated clear distinction between groups using graphene sensors functionalized with 100 & micro;g of N-nucleocapsid phosphoprotein. The same result of ELISA validation, showing 100% sensitivity and specificity. The improvement in the performance of the graphene-based ME biosensor scales with surface biofunctionalization, which is performed effectively and reproducibly, as a result of assays on the optimization of protein concentration and biofunctionalization time. The platform combines graphene's advantages with the wireless, real-time detection capabilities of ME biosensors, demonstrating potential for future low-cost and portable point-of-care diagnostic applications.

We report here the growth of ultrathin films of ceria by pulsed laser deposition on HOPG/graphene substrates. The controlled growth of CeO2(111) nanoislands on graphene via pulsed laser deposition (PLD) demonstrates a strong dependence on the substrate defect density, where defects serve as preferential nucleation sites. Higher oxygen partial pressure during deposition enhances surface diffusion, promoting the formation of triangular dendritic nanostructures. Scanning tunneling spectroscopy (STS) reveals mutual electronic interactions between the ceria nanoislands and the graphene substrate, while high-resolution STM imaging identifies ordered oxygen vacancy arrays within the CeO2 surface. Bias-dependent STM mapping further highlights the complex electronic configuration of the islands. The presence of these ordered defects suggests the potential for precise spatial control, enabling tailored electronic properties through doping or optimized graphene interactions. These findings advance defect-engineered oxide nanostructures, offering promising applications in catalysis, sensing, and optoelectronics via vacancy manipulation in ultrathin films.

Through the description of the methodology of the development of a bite force measurement device it will be shown how interdisciplinary work of Engineers and Health Professionals bring enhance of life quality to general population. Bite force measurement is a reliable exam to check stomatognathic system (SS) conditions. In order to provide a reliable, low cost and do-it-yourself gnathodynamometer a Dentist joined Bioengineering Laboratory (LabBio) at UFMG. The development of a 3D printed resin structure was made using CAD/CAM and tested by means of FEM. A Carbon Nano Tube (CNT) extensometer developed at CTNANO at UFMG to capture the structure deformation were fixed in two geometries that showed good results in FEM simulation and will be tested in an EMIC universal mechanical testing machine (DL1000) equipped with a 1 kN load cell. The electrical response of the extensometers was monitored using a Keithley 2000 digital multimeter (Tektronix), connected to a computer and remotely controlled by a LabView application (View Point Systems), a data storage protocol in a SD card and in the clouds using IoT and an data acquisition system will be tested. In bench tests both geometries showed good results with deformation capturable from 40 N. Data was codified using an Arduino Nano and a program was developed for data acquisition and storage. The interdisciplinary work generates prototypes with promising results in bench tests. The fruit of the team work may generate a toll that improves life quality of population by allowing more people to be tested and lowering health costs.

In this paper, we adopt a novel approach to investigate the ionic conduction near the percolation transition in a porous nanomaterial. We make use of a recently discovered humidity sensing property of aerosol-printed MoS2 ink films, where the conductance, originated from ionic transport through water nanochannels within the films, is dependent on the ambient humidity. The experiments, performed for a set of four devices inside a chamber with controlled humidity, allow the experimental fine-tuning of the ionic conduction percolation within each nanoporous device by changing the ambient relative humidity, without the need of different samples for different stoichiometries as in usual percolation experiments. Our results indicate the existence, in our devices, of a common phenomenology consisting of two sequential modifications of the conductance as a function of humidity near percolation. The first is the true percolation transition with a universal critical exponent very close to unity. This is followed by an apparent increase in the critical exponent above the true transition. We also perform molecular dynamics simulations that allow the identification of a possible mechanism for dimensionality changes in the water nanochannels inside the material as a function of either humidity or material geometry as a possible scenario for the observed conductance modification in the conductive phase.

Anais do Congresso Internacional de Engenharia Mecânica e Industrial (2764-4294) - Uso De Cad/Cam, Nanotecnologia, Método De Elementos Finitos, Intenet Of Things E Impressão 3D No Desenvolvimento De Um Dispositivo De Medição De Força De Mordida De Baixo Custo.

OBJECTIVE:Present a gnathodynamometer design that increases patient comfort, precision, and/or ease for the operator during bite force tests.MATERIALS AND METHODS:A bite tip capable of pivoting 180° was tested on senior dental students in a double-blind trial. The tests were performed in teeth 11 and 16 with the bite tip on the long axis of the clamp and at an angle of 90° to the clamp. The sample was composed of 24 students, 13 males and 11 females, randomly divided into two groups: the operator group (OP), which was composed of 12 students, 7 males and 5 females, and the test group (TI), which was composed of 12 students, 6 males and 6 females. The operator and participants were asked to evaluate comfort and precision/ease in positioning the bite tip by attributing scores from 0 (total discomfort) to 10 (total comfort) during the test.RESULTS:No difference was noted in tooth 11 (P > 0.05). In tooth 16, there was a statistically significant improvement (P < 0.01) for the participants tested and the operator using the pivoting bite tip.CONCLUSIONS:The pivoting bite tip showed no difference in the comfort of the participants and operator precision when testing incisors; however, the tip showed a difference for both conditions in the molar region. The gnathodynamometer geometry showed good results in participant comfort and operator precision when used in bite force tests of the incisors and molars. Further investigations are needed to confirm whether these improvements influence the mean value and maximum bite force measurement.CLINICAL RELEVANCE:Bite force measurement is a method for obtaining important data to check the functional conditions of the stomatognathic system. With the aging of the world population, it has become important to check the quality of life during aging. The pivoting bite tip improves the comfort and precision of bite tests for the participants tested and for the operator, respectively.

In this work, a conductive ink based on microfibrillated cellulose (MFC) and multiwalled carbon nanotubes (MWCNTs) was used to produce transducers for rapid liquid identification. The transducers are simple resistive devices that can be easily fabricated by scalable printing techniques. We monitored the electrical response due to the interaction between a given liquid with the carbon nanotube–cellulose film over time. Using principal component analysis of the electrical response, we were able to extract robust data to differentiate between the liquids. We show that the proposed liquid sensor can classify different liquids, including organic solvents (acetone, chloroform, and different alcohols) and is also able to differentiate low concentrations of glycerin in water (10–100 ppm). We have also investigated the influence of two important properties of the liquids, namely dielectric constant and vapor pressure, on the transduction of the MFC-MWCNT sensors. These results were corroborated by independent heat flow measurements (thermogravimetric analysis). The proposed MFC-MWCNT sensor platform may help paving the way to rapid, inexpensive, and robust liquid analysis and identification.

Molybdenum disulfide (MoS2) is attractive for use in next-generation nanoelectronic devices and exhibits great potential for humidity sensing applications. Herein, MoS2 ink was successfully prepared via a simple exfoliation method by sonication. The structural and surface morphology of a deposited ink film was analyzed by scanning electron microscopy (SEM), Raman spectroscopy, and atomic force microscopy (AFM). The aerosol-printed MoS2 ink sensor has high sensitivity, with a conductivity increase by 6 orders of magnitude upon relative humidity increase from 10 to 95% at room temperature. The sensor also has fast response/recovery times and excellent repeatability. Possible mechanisms for the water-induced conductivity increase are discussed. An analytical model that encompasses two ionic conduction regimes, with a percolation transition to an insulating state below a low humidity threshold, describes the sensor response successfully. In conclusion, our work provides a low-cost and straightforward strategy for fabricating a high-performance humidity sensor and fundamental insights into the sensing mechanism.

In the present work, we apply a microfluidic channel platform to study mechanical and adhesion properties of suspended graphene in contact with oleic acid (a lipid). In the platform, one side of the suspended graphene, atop a window in a fluidic channel, is placed in contact with the lipid, and the mechanical response of graphene is experimentally accessed with an atomic force microscope probe. We observe a strong effect arising from the presence of oleic acid: the probe undergoes a large jump-to-contact effect, being pulled and partially encapsulated by graphene, in a phagocytosis-like phenomenon, until it penetrates 0.2 µm into graphene. In contrast, such encapsulation effect is negligible in the absence of oleic acid in the channel, with probe penetration of less than 0.02 µm. The lipid-induced encapsulation effect is observed to occur concurrently with graphene delamination from the window walls. Molecular dynamics simulations and continuum mechanics analytical modeling are also performed, the latter allowing quantitative fittings to the experiments.

Some sub-products from the industrial activity are rich in metals, very often being highly toxic to human health and to the environment. Thus, the development of real-time and ultrasensitive techniques for metals detection is relevant. Herein, we report an ion-sensitive field-effect transistor (ISFET) based on l-phenylalanine functionalized graphene that detects Na+, Co2+, and Al3+ at the nanomolar range and Cu2+ at the picomolar range. Our sensor is prepared using a simple functionalization method and is reusable after a standard HCl cleaning process. Altogether, the ISFET is a promising device for real-time detection of metal ions at low concentrations.

In this work, we report a buckypaper composite with properties suitable for high performance electrodes of redox supercapacitors. The synthesis employs a specific combination of the double- and triple-walled carbon nanotubes (FWCNT) with cellulose nanofibrils (CNF), with dimensions of 20-50 nm in width and lengths of up to several hundred microns. The generated composite (BP/CNT@CNF) preserves the structure of the FWCNTs and ensures greater wettability, without significant damage to electrical conductivity. When compared to a buckypaper produced without CNF, BP/CNT@CNF is completely moldable and flexible, with an increase of about 375% in tensile strength, and 400% in the maximum strain. As electrodes, BP/CNT@CNF is stable in different aqueous redox electrolytes at different pHs containing hydroquinone (HQ in 1.0 M H2SO4), potassium hexacyanoferrate(II) (K-4[Fe(CN)(6)] in 3.0 M KOH) and KBr in neutral medium. In all media, excellent capacitance retentions are obtained, evaluated in 12,000 cycles. The best electrochemical performances are obtained with HQ/H2SO4 as a redox electrolyte. High specific capacitance values are found from 1 A g(-1) (380.8 F g(-1)) to 15 A g(-1) (216.1 F g(-1)), with energy and power densities corresponding to 28.2 W h kg(-1) and 3974.7 W kg(-1), respectively, calculated at electrode level. (c) 2020 Elsevier Ltd. All rights reserved.

Inducing electrostatic doping in 2D materials by laser exposure (photodoping effect) is an exciting route to tune optoelectronic phenomena. However, there is a lack of investigation concerning in what respect the action of photodoping in optoelectronic devices is local. Here, we employ scanning photocurrent microscopy (SPCM) techniques to investigate how a permanent photodoping modulates the photocurrent generation in MoS2 transistors locally. We claim that the photodoping fills the electronic states in MoS2 conduction band, preventing the photon-absorption and the photocurrent generation by the MoS2 sheet. Moreover, by comparing the persistent photocurrent (PPC) generation of MoS2 on top of different substrates, we elucidate that the interface between the material used for the gate and the insulator (gate-insulator interface) is essential for the photodoping generation. Our work gives a step forward to the understanding of the photodoping effect in MoS2 transistors and the implementation of such an effect in integrated devices.

This work presents a detailed experimental investigation of the interaction between molecular hydrogen (H 2 ) and monolayer MoS 2 field effect transistors (MoS 2 FET), aiming for sensing application. The MoS 2 FET exhibits a response to H 2 that covers a broad range of concentration (0.1–90%) at a relatively low operating temperature range (300–473 K). Most important, H 2 sensors based on MoS 2 FETs show desirable properties such as full reversibility and absence of catalytic metal dopants (Pt or Pd). The experimental results indicate that the conductivity of MoS 2 monotonically increases as a function of the H 2 concentration due to a reversible charge transferring process. It is proposed that such process involves dissociative H 2 adsorption driven by interaction with sulfur vacancies in the MoS 2 surface ( V S ). This description is in agreement with related density functional theory studies about H 2 adsorption on MoS 2 . Finally, measurements on partially defect‐passivated MoS 2 FETs using atomic layer deposited aluminum oxide consist of an experimental indication that the V S plays an important role in the H 2 interaction with the MoS 2 . These findings provide insights for future applications in catalytic process between monolayer MoS 2 and H 2 and also introduce MoS 2 FETs as promising H 2 sensors.

This article shows that the spin-to-charge current conversion in single-layer graphene (SLG) by means of the inverse Rashba-Edelstein effect (IREE) is made possible with the integration of this remarkable 2D-material with the unique ferrimagnetic insulator yttrium iron garnet (YIG = $Y_{3}Fe_{5}O_{12}$) as well as with the ferromagnetic metal permalloy (Py = $Ni_{81}Sb_{19}$). By means of X-ray absorption spectroscopy (XAS) and magnetic circular dichroism (XMCD) techniques, we show that the carbon atoms of the SLG acquires an induced magnetic moment due to the proximity effect with the magnetic layer. The spin currents are generated in the magnetic layer by spin pumping from microwave driven ferromagnetic resonance and are detected by a dc voltage along the graphene layer, at room temperature. The spin-to-charge current conversion, occurring at the graphene layer, is explained by the extrinsic spin-orbit interaction (SOI) induced by the proximity effect with the ferromagnetic layer. The results obtained for the SLG/YIG and SLG/Py systems confirm very similar values for the IREE parameter, which are larger than the values reported in previous studies for SLG. We also report systematic investigations of the electronic and magnetic properties of the SLG/YIG by means of scanning tunneling microscopy (STM).

Here we present a graphene chip designed to nanoscale infrared analysis of materials in liquid environments. We measured the local chemistry of protein clusters in water and a variety of biocompatible liquids.

Non-volatile memory devices have been limited to flash architectures that are complex devices. Here, we present a unique photomemory effect in MoS$_2$ transistors. The photomemory is based on a photodoping effect - a controlled way of manipulating the density of free charges in monolayer MoS$_2$ using a combination of laser exposure and gate voltage application. The photodoping promotes changes on the conductance of MoS$_2$ leading to photomemory states with high memory on/off ratio. Such memory states are non-volatile with an expectation of retaining up to 50 % of the information for tens of years. Furthermore, we show that the photodoping is gate-tunable, enabling control of the recorded memory states. Finally, we propose a model to explain the photodoping, and we provide experimental evidence supporting such a phenomenon. In summary, our work includes the MoS$_2$ phototransistors in the non-volatile memory devices and expands the possibilities of memory application beyond conventional memory architectures.

In this work, we present an investigation regarding how and why molecular hydrogen (H-2) changes the electronic properties of graphene field effect transistors (GFETs). We demonstrate that interaction with H-2 leads to local doping of graphene near of the graphene-contact heterojunction. We also show that such interaction is strongly dependent on the characteristics of the metal-graphene interface. By changing the type of metal in the contact, we observe that Ohmic contacts can be strongly or weakly electrostatically coupled with graphene. For strongly coupled contacts, the signature of the charge transfer effect promoted by the contacts results on asymmetric ambipolar conduction, and such asymmetry can be tunable under interaction with H-2. On the other hand, for contacts weakly coupled with graphene, the hydrogen interaction has a more profound effect. In such a situation, the devices show a second charge neutrality point (CNP) in graphene transistor transfer curves (a double-peak response) upon H-2 exposure. We propose that this double-peak phenomenon arises from the decoupling of the work function of graphene and that of the metallic electrodes induced by the H-2 molecules. We also show that the gas-induced modifications at the metal-graphene interface can be exploited to create a controlled graphene p-n junction, with considerable electron transfer to graphene layer and significant variation in the graphene resistance. These effects can pave the way for a suitable metallic contact engineering providing great potential for the application of such devices as gas sensors.

nanotubes (CNT) in several industries and technological applications, it is essential to perform in vivo toxicological studies with these nanomaterials to evaluate their potential ecotoxicity. Dopamine (DA) and serotonin (5HT) are key neurotransmitters for brain functions and behavioral responses. Determination of DA and 5HT were performed in brain samples from zebra fi sh Danio rerio exposed i.p. to single-walled CNT (SWCNT), besides analyzing acetylcholinesterase (AChE) and ectonucleotidases activity, lipid per-oxidation and total antioxidant capacity. Results showed that treatment with SWCNT increased between 3 and 6-fold the concentration of DA and 5HT ( p < 0.05). Similarly, a signi fi cant reduction ( p < 0.05) in AChE activity was observed in the brains of SWCNT exposed zebra fi sh when compared to the control groups. Cholinergic, serotonergic, and dopaminergic systems, through AChE activity and serotonin and dopamine levels, respectively were a ff ected by SWCNT in the zebra fi sh brain. Alterations in these neurotransmitters can potentially a ff ect several physiological and behavioral that they control.