Browsing by Author "Cunha, Thiago Henrique Rodrigues da"

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    Aerosol-printed MoS2 ink as a high sensitivity humidity sensor.
    (2022) Pereira, Neuma das Mercês; Rezende, Natália Pereira; Cunha, Thiago Henrique Rodrigues da; Barboza, Ana Paula Moreira; Silva, Glaura Goulart; Lippross, Daniel; Neves, Bernardo Ruegger Almeida; Chacham, Helio; Ferlauto, Andre Santarosa; Lacerda, Rodrigo Gribel
    Molybdenum disulfide (MoS2) is attractive for use in nextgeneration 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 highperformance humidity sensor and fundamental insights into the sensing mechanism.
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    Carbon nanotube-cellulose ink for rapid solvent identification.
    (2023) Cardoso, Tiago Amarante de Barros; Cunha, Thiago Henrique Rodrigues da; Moreira, Claudio Laudares; Barboza, Ana Paula Moreira; Santos, Ana Carolina dos; Pereira, Cíntia Lima; Silva, Vinícius Ornelas da; Neves, Bernardo Ruegger Almeida; Ferlauto, Andre Santarosa; Lacerda, Rodrigo Gribel
    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 mea- surements (thermogravimetric analysis). The proposed MFC-MWCNT sensor platform may help paving the way to rapid, inexpensive, and robust liquid analysis and identification.
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    Room temperature observation of the correlation between atomic and electronic structure of graphene on Cu(110).
    (2016) Silva, Thais Chagas Peixoto; Cunha, Thiago Henrique Rodrigues da; Matos, Matheus Josué de Souza; Reis, Diogo Duarte dos; Araujo, Karolline Aparecida de Souza; Malachias, Angelo; Mazzoni, Mario Sergio de Carvalho; Ferlauto, Andre Santarosa; Paniago, Rogério Magalhães
    In this work we have used atomically-resolved scanning tunneling microscopy and spectroscopy to study the interplay between the atomic and electronic structure of graphene formed on copper via chemical vapor deposition. Scanning tunneling microscopy directly revealed the epitaxial match between a single layer of graphene and the underlying copper substrate in different crystallographic orientations. Using scanning tunneling spectroscopy we have directly measured the electronic density of states of graphene layers near the Fermi level, observing the appearance of a series of peaks in specific cases. These features were analyzed in terms of substrate-induced perturbations in the structural and electronic properties of graphene by means of atomistic models supported by density functional theory calculations.