Measurement of Flexural Rigidity of Multi-Walled Carbon Nanotubes by Dynamic Scanning Electron Microscopy

Fortini, Renata; Meyer‐Plath, Asmus; Kehren, Dominic; Gernert, Ulrich; Jácome, Leonardo Agudo; Sturm, Heinz

doi:10.3390/fib8050031

Cited by 8 publications

(9 citation statements)

References 60 publications

(92 reference statements)

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“…With the aim of reducing the analysis effort to a practicable amount, we propose using the so-called fiber rigidity hypothesis [6,8,30,31]. It toxicologically motivates ignoring a specific fraction of thin fibers and thus permits reducing the resolution of image acquisition.…”

Section: Workload Reduction By Introducing a Cut-off Diametermentioning

confidence: 99%

A Practicable Measurement Strategy for Compliance Checking Number Concentrations of Airborne Nano- and Microscale Fibers

et al. 2020

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Despite compelling reports on asbestos-like pathogenicity, regulatory bodies have been hesitant to implement fiber number-based exposure limits for biodurable nanoscale fibers. One reason has been the lack of a practicable strategy for assessing airborne fiber number concentrations. Here, a method is proposed, detailed and tested for compliance checking concentrations of airborne nano- and microscale fibers. It relies on Poisson statistical significance testing of the observed versus a predicted number of fibers on filters that have sampled a known volume of aerosol. The prediction is based on the exposure concentration to test. Analogous to the established counting rules for WHO-fibers, which use a phase contrast microscopy-related visibility criterion of 200 nm, the new method also introduces a cut-off diameter, now at 20 nm, which is motivated by toxicological findings on multi-walled carbon nanotubes. This cut-off already reduces the workload by a factor of 400 compared to that necessary for imaging, detecting and counting nanofibers down to 1 nm in diameter. Together with waiving any attempt to absolutely quantify fiber concentrations, a compliance check at the limit-of-detection results in an analytical workload that renders our new approach practicable. The proposed method was applied to compliance checking in 14 very different workplaces that handled or machined nanofiber-containing materials. It achieved detecting violations of the German benchmark exposure level of 10,000 nanofibers per cubic meter.

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Section: Workload Reduction By Introducing a Cut-off Diametermentioning

confidence: 99%

A Practicable Measurement Strategy for Compliance Checking Number Concentrations of Airborne Nano- and Microscale Fibers

et al. 2020

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“…Further investigation of the post-curing process with light on suitable geometries, with AFM on stiffness and surface adhesion [50], as well as to make measurements of the resonance frequency of beams to determine the bending modulus [51] are advised for a deeper understanding of fs-LDW structures. In contrast to thermal post-curing, the geometric dimensions change only slightly because the structures do not expand before the curing leads to shrinkage.…”

Section: Discussionmentioning

confidence: 99%

First of its kind: a test artifact for direct laser writing

Fritzsche

Weimann

Pauw

et al. 2023

Meas. Sci. Technol.

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With Direct Laser Writing (DLW) maturing in all aspects as a manufacturing technology a toolset for quality assurance must be developed.In this work we want to introduce a first of its kind test artifact. Test artifacts are standardized 3D models with specific geometric feature to evaluate the performance of writing parameters.Test artifacts are already common in other 3D additive manufacturing technologies e.g. Selective Laser Melting. The test artifact introduced in this work was developed in particular to accommodate 1) the high geometrical resolution of DLW structures and 2) the limited possibilities to examine the resulting structure.Geometric accuracy, surface adhesion as well as confocal raman spectroscopy results were considered when evaluating the design of the test artifact.We will explain the individual features and design considerations of our DLW test artifact. The difference between two slicers, Cura and 3DPoli, and the implications on measured feature sizes and the general shape is quantified. The measured geometries are used to derive a general design guide for a specific combination of photoresist, laser power and scanning speed and to analyse the geometric accuracy of a structure produced using these guidelines.

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“…However, a simple post-curing with visible light could solve the problem, and this would also make optical and mechanical microstructures more stable. It is planned to carry out a further investigation of this post-curing with light on suitable geometries, with AFM on stiffness and surface adhesion [43], as well as to make measurements of the resonance frequency of beams to determine the bending modulus [44]. In contrast to thermal post-curing, the geometric dimensions change only slightly because the structures do not expand before the curing leads to shrinkage.…”

Section: Discussionmentioning

confidence: 99%

First of its Kind: A Test Artifact for Direct Laser Writing

Fritzsche¹,

Pauw²,

Weimann³

et al. 2022

Preprint

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With Direct Laser Writing (DLW) maturing in all aspects as a manufacturing technology a toolset for quality assurance must be developed. In this work we want to introduce a first of its kind test artifact. Test artifacts are standardized 3D models with specific geometric feature to evaluate the performance of writing parameters. Test artifacts are already common in other 3D additive manufacturing technologies e.g. Selective Laser Melting. The test artifact introduced in this work was developed in particular to accommodate 1) the high geometrical resolution of DLW structures and 2) the limited possibilities to examine the resulting structure. Geometric accuracy, surface adhesion as well as confocal raman spectroscopy results were considered when evaluating the design of the test artifact. We will explain the individual features and design considerations of our DLW test artifact. The difference between two slicers, Cura and 3DPoli, and the implications on measured feature sizes and the general shape is quantified. The measured geometries are used to derive a general design guide for a specific combination of photoresist, laser power and scanning speed and to analyse the geometric accuracy of a structure produced using these guidelines.

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Measurement of Flexural Rigidity of Multi-Walled Carbon Nanotubes by Dynamic Scanning Electron Microscopy

Cited by 8 publications

References 60 publications

A Practicable Measurement Strategy for Compliance Checking Number Concentrations of Airborne Nano- and Microscale Fibers

A Practicable Measurement Strategy for Compliance Checking Number Concentrations of Airborne Nano- and Microscale Fibers

First of its kind: a test artifact for direct laser writing

First of its Kind: A Test Artifact for Direct Laser Writing

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