Nanocrystalline graphite thin layers for low-strain, high-sensitivity piezoresistive sensing

Simionescu, Octavian‐Gabriel; Pachiu, Cristina; Ionescu, Octavian; Dumbrǎvescu, Niculae; Buiu, O.; Popa, R.; Avram, Andrei; Dinescu, Gheorghe

doi:10.1515/rams-2020-0031

Cited by 13 publications

(12 citation statements)

References 40 publications

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“…As a last comment, Zhao et al [ 24 ] reported that as they reduced the grain size from 25 to 8 nm, the GF increased from 11 to 600. Also, Simionescu et al [ 33 ] reported a varying GF (50–250) for a strain range of 0%–1%. In this work, NCG with lower grain sizes has been obtained; however, the GF does not appear to further increase and remains comparable to the values of previously reported works.…”

Section: Resultsmentioning

confidence: 99%

On the mechanism of piezoresistance in nanocrystalline graphite

Kumar,

Dehm,

Krupke

2024

Beilstein J. Nanotechnol.

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Strain sensors are sensitive to mechanical deformations and enable the detection of strain also within integrated electronics. For flexible displays, the use of a seamlessly integrated strain sensor would be beneficial, and graphene is already in use as a transparent and flexible conductor. However, graphene intrinsically lacks a strong response, and only by engineering defects, such as grain boundaries, one can induce piezoresistivity. Nanocrystalline graphene (NCG), a derivative form of graphene, exhibits a high density of defects in the form of grain boundaries. It holds an advantage over graphene in easily achieving wafer-scale growth with controlled thickness. In this study, we explore the piezoresistivity in thin films of nanocrystalline graphite. Simultaneous measurements of sheet resistance and externally applied strain on NCG placed on polyethylene terephthalate (PET) substrates provide intriguing insights into the underlying mechanism. Raman measurements, in conjunction with strain applied to NCG grown on flexible glass, indicate that the strain is concentrated at the grain boundaries for smaller strain values. For larger strains, mechanisms such as grain rotation and the formation of nanocracks might contribute to the piezoresistive behavior in nanocrystalline graphene.

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Section: Resultsmentioning

confidence: 99%

On the mechanism of piezoresistance in nanocrystalline graphite

Kumar,

Dehm,

Krupke

2024

Beilstein J. Nanotechnol.

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“…The deposition technique offers the advantage of growing the films directly on an insulating layer (i.e., SiO

), thus eliminating the need for an ulterior transfer step, which, for example, is required for the SLG thin films. The bulk-NCG thin films are grown with a previously established process [ 37 , 38 , 39 ], in a CH

(60:75 sccm) atmosphere, at a pressure of 200 Pa and an RF discharge power of 100 W. The substrate temperature is kept at a high value of 890–900 °C, over a two h plasma growth step, to promote a high nucleation density. This in turn will result in thin films with high edge defect density, which is beneficial for sensors that rely on conductivity variations due to particle surface adsorption [ 37 ].…”

Section: Materials and Methodsmentioning

confidence: 99%

Field-Effect Transistors Based on Single-Layer Graphene and Graphene-Derived Materials

et al. 2023

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The progress of advanced materials has invoked great interest in promising novel biosensing applications. Field-effect transistors (FETs) are excellent options for biosensing devices due to the variability of the utilized materials and the self-amplifying role of electrical signals. The focus on nanoelectronics and high-performance biosensors has also generated an increasing demand for easy fabrication methods, as well as for economical and revolutionary materials. One of the innovative materials used in biosensing applications is graphene, on account of its remarkable properties, such as high thermal and electrical conductivity, potent mechanical properties, and high surface area to immobilize the receptors in biosensors. Besides graphene, other competing graphene-derived materials (GDMs) have emerged in this field, with comparable properties and improved cost-efficiency and ease of fabrication. In this paper, a comparative experimental study is presented for the first time, for FETs having a channel fabricated from three different graphenic materials: single-layer graphene (SLG), graphene/graphite nanowalls (GNW), and bulk nanocrystalline graphite (bulk-NCG). The devices are investigated by scanning electron microscopy (SEM), Raman spectroscopy, and I-V measurements. An increased electrical conductance is observed for the bulk-NCG-based FET, despite its higher defect density, the channel displaying a transconductance of up to ≊4.9×10−3 A V−1, and a charge carrier mobility of ≊2.86×10−4 cm2 V−1 s−1, at a source-drain potential of 3 V. An improvement in sensitivity due to Au nanoparticle functionalization is also acknowledged, with an increase of the ON/OFF current ratio of over four times, from ≊178.95 to ≊746.43, for the bulk-NCG FETs.

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Section: Introductionmentioning

confidence: 99%

“…To improve the properties of sensors, flexible sensors with diverse structures have been prepared by various processing methods; including electrospinning, vapor chemical deposition, casting, and 3D printing technology. [10][11][12] However, these methods are disadvantageous in terms of low efficiency, high cost, and difficult industrial production. Biaxial stretching is a simple and effective film preparation technology, which is also a deformation form in some polymer processing approaches, such as thermoforming, film blowing, and extrusion.…”

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confidence: 99%

Flexible strain sensors with high sensitivity and large working range prepared from biaxially stretched carbon nanotubes/polyolefin elastomer nanocomposites

Xiang

Chen

et al. 2022

J of Applied Polymer Sci

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Flexible strain sensors are a new generation of flexible and stretchable electronic devices that attracted increasing attention due to their practical applications in many fields. However, maintaining a wide detectable strain range while improving the sensitivity of flexible strain sensors remains challenging. In this study, flexible strain sensors with a large working range based on biaxially stretched carbon nanotubes (CNTs)/polyolefin elastomer (POE) nanocomposites were fabricated. Biaxial stretching was demonstrated to enhance the uniform dispersion and orientation of CNTs, thereby improving the performance of sensors. The optimal stretching ratios (SRs) of nanocomposites were investigated and the data revealed an increment in the sensitivity of sensors with SRs, while the working range first increased after biaxial stretching and decreased at higher SRs. Compared to the 9 wt% CNT/POE‐1.0 sensor with a gauge factor (GF) value of 2.37 and a detectable range of 0.5%–230%, the CNT/POE‐2.0 sensor exhibited an enhanced sensitivity (GF = 3935.12) coupled with a wider detectable range (0.5%–710%) and better stability. Besides, CNT/POE‐2.0 sensor also achieved the monitoring of head movements, mouth opening, facial expression, and physiological signals, showing a potential for use in wearable electronic products.

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Nanocrystalline graphite thin layers for low-strain, high-sensitivity piezoresistive sensing

Cited by 13 publications

References 40 publications

On the mechanism of piezoresistance in nanocrystalline graphite

On the mechanism of piezoresistance in nanocrystalline graphite

Field-Effect Transistors Based on Single-Layer Graphene and Graphene-Derived Materials

Flexible strain sensors with high sensitivity and large working range prepared from biaxially stretched carbon nanotubes/polyolefin elastomer nanocomposites

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