Exploring the limits of sensitivity for strain gauges of graphene and hexagonal boron nitride decorated with metallic nanoislands

Ramírez, Julián; Urbina, Armando D.; Kleinschmidt, Andrew T.; Finn, Mickey; Edmunds, Samuel J.; Esparza, Guillermo L.; Lipomi, Darren J.

doi:10.1039/d0nr02270e

Cited by 11 publications

(12 citation statements)

References 67 publications

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“…As an example, graphene oxide also exhibits a good barrier performance against air and water, 60 although thickness would need to be carefully controlled to retain optical transmissibility. 61 Meanwhile, hexagonal boron nitride has recently emerged as a promising new 2D material and exhibits excellent transparency due to its wide bandgap, 62 although it tends to have smaller grains than CVD graphene, 63 which could exacerbate the leakage issues we observed.…”

Section: Resultsmentioning

confidence: 99%

Stability of Perovskite Films Encapsulated in Single- and Multi-Layer Graphene Barriers

Runser

Kodur

Skaggs

et al. 2021

ACS Appl. Energy Mater.

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This paper describes the efficacy of barrier films coated with single- and multi-layer graphene in preventing degradation of perovskite films in air. Despite the impermeability of graphene to small species such as water and oxygen, the presence of numerous grain boundaries and defects in chemical vapor deposition (CVD)-grown graphene monolayer films can present pathways for permeation. However, the availability of these pathways can in principle be reduced by stacking multiple layers of graphene on top of each other. The barrier material considered here consists of the semi-permeable polymer parylene laminated with either 0, 1, 2, or 3 monolayers of graphene. These composite films are used to encapsulate triple cation perovskite films, which are then subjected to a degradation test under damp heat. We find that a monolayer of graphene confers a 15-fold reduction in degradation compared to the parylene films with no graphene and that three-layer graphene can yield a further 2× reduction in degradation. Although all of our films encapsulated with graphene/parylene exhibited substantial degradation compared to films encapsulated in glass with polyisobutylene edge seals, our results nonetheless reinforce the utility of graphene barriers for less demanding applications, including lightweight or flexible perovskite solar cells with shorter anticipated lifetimes.

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Section: Resultsmentioning

confidence: 99%

Stability of Perovskite Films Encapsulated in Single- and Multi-Layer Graphene Barriers

Runser

Kodur

Skaggs

et al. 2021

ACS Appl. Energy Mater.

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“…Due to this interplay of energies, the evaporation of gold on graphene is biased toward island-like growth at low nominal thicknesses. The details of this process are discussed elsewhere. , The graphene–metal composite film is overlayed with a thin film of a highly plasticized conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The thinness and stretchability of the sensor permits it to be transferred onto many types of substrate .…”

Section: Experimental Designmentioning

confidence: 99%

Epidermal Graphene Sensors and Machine Learning for Estimating Swallowed Volume

Polat

Becerra

Hsu

et al. 2021

ACS Appl. Nano Mater.

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Assessment of liquid intake is necessary to obtain a complete picture of an individual's hydration status. Measurements using state-of-theart wearable devices have been demonstrated, but none of these devices have combined high sensitivity, unobtrusiveness, and automated estimation of volume, i.e., using machine learning. Such a capability would have immense value in a variety of medical contexts, such as monitoring patients with dysphagia or the performance of athletes. Here, an epidermal sensor platform is combined with machine learning to measure swallowed liquid volume based on signals obtained from the surface of the skin. The key component of the device is a composite piezoresistive sensor consisting of single-layer graphene decorated with metallic nanoislands and coated with a highly p l a s t i c i z e d f o r m o f t h e c o n d u c t i v e p o l y m e r p o l y ( 3 , 4ethylenedioxythiophene):poly(styrenesuflonate) (PEDOT:PSS). Surface electromyography (sEMG) signals obtained with conventional electrodes are used in concert with the strain measurements. The use of strain and sEMG measurements together both (1) improve the accuracy of estimated volumes and (2) permit the differentiation of swallowing from motion artifacts. In a cohort consisting of 11 participants, the combined measurements of strain and sEMGprocessed by the machine learning algorithmwere able to estimate unknown swallowed volumes cumulatively between 5 and 30 mL of water with greater than 92% accuracy. Ultimately, this system holds promise for numerous applications in sports medicine, rehabilitation, and the detection of nascent dysfunction in swallowing.

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“…29 Thus, it would be possible to separate contributions of metal to the piezoresistance of the composite film from those of the graphene. 30 We first compared the morphologies of these metal films on single-layer graphene and hexagonal boron nitride to gain insight into the influence of the 2D substrates on the morphology of the metal film being deposited. Through analysis of scanning and transmission electron microscopy (SEM and TEM) images, we were able to calculate the fractional coverage, extent of connectivity, and percolation thresholds as a function of nominal thickness of the metallic film on each of the 2D substrates.…”

Section: ■ Developments In Wearable Applicationsmentioning

confidence: 99%

“…While graphene is a conductor and exhibits piezoresistance, hBN is an insulator and has no electrical response to strain . Thus, it would be possible to separate contributions of metal to the piezoresistance of the composite film from those of the graphene . We first compared the morphologies of these metal films on single-layer graphene and hexagonal boron nitride to gain insight into the influence of the 2D substrates on the morphology of the metal film being deposited.…”

Section: Assaying Cellular Biomechanicsmentioning

confidence: 99%

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Metallic Nanoislands on Graphene for Biomechanical Sensing

2020

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This minireview describes a nanomaterial-based multimodal sensor for performing biomechanical measurements. The sensor consists of ultrathin metallic films on single-layer graphene. This composite material exhibits physical properties that neither material possesses alone. For example, the metal, deposited by evaporation at low (≤10 nm) nominal thicknesses, renders the film highly sensitive to mechanical stimuli, which can be detected using electrical (i.e., resistance) and optical (i.e., plasmonic) modalities. The electrical modality, in particular, is capable of resolving deformations as small as 0.0001% engineering strain, or 1 ppm. The electrical and optical responses of the composite films can be tailored by controlling the morphology of the metallic film. This morphology (granular or island-like when deposited onto the graphene) can be tuned using the conditions of deposition, the identity of the substrate beneath the graphene, or even the replacement of the graphene for hexagonal boron nitride (hBN). This material responds to forces produced by a range of physiological structures, from the contractions of heart muscle cells, to the beating of the heart through the skin, to stretching of the skin due to the expansion of the lungs and movement of limbs. Here, we provide an update on recent applications of this material in fields ranging from cardiovascular medicine (by measuring the contractions of 2D monolayers of cardiomyocytes), regenerative medicine (optical measurements of the forces produced by myoblasts), speech pathology and physical therapy (measuring swallowing function in head and neck cancer survivors), lab-on-a-chip devices (using deformation of sidewalls of microfluidic channels to detect transiting objects), and sleep medicine (measuring pulse and respiration with a wearable, unobtrusive device). We also discuss the mechanisms by which these films detect strain.

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Exploring the limits of sensitivity for strain gauges of graphene and hexagonal boron nitride decorated with metallic nanoislands

Abstract: The purpose of this work is to clarify the mechanism of piezoresistance in a class of ultra-sensitive strain gauges based on metallic films on 2D substrates (“2D/M” films).

Cited by 11 publications

References 67 publications

Stability of Perovskite Films Encapsulated in Single- and Multi-Layer Graphene Barriers

Stability of Perovskite Films Encapsulated in Single- and Multi-Layer Graphene Barriers

Epidermal Graphene Sensors and Machine Learning for Estimating Swallowed Volume

Metallic Nanoislands on Graphene for Biomechanical Sensing

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