The importance of shear thinning, thixotropic and viscoelastic properties of thick film pastes to predict effects on printing performance

Reinhardt, Kathrin; Hofmann, Nancy R.; Eberstein, Markus

doi:10.23919/empc.2017.8346831

Cited by 14 publications

(36 citation statements)

References 10 publications

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“…The viscosity of the colloidal systems is also dependent on the topography and shape of the suspended particles. From Reinhardt et al, a correlation between the shape of a suspended particle (flakes suspensions as in graphene-based inks) and its viscosity are determined, shown below in Figure 4 [18]. This shows that the shear-thinning behavior in the shear rate γ <· 1 s −1 is intensified for flake suspensions, giving similar viscosity within the shear-thinning region, while generally having higher viscosity compared to the sphere-shaped suspensions, as seen in Figure 4.…”

Section: Introductionmentioning

confidence: 99%

Rheological Issues in Carbon-Based Inks for Additive Manufacturing

et al. 2019

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As the industry and commercial market move towards the optimization of printing and additive manufacturing, it becomes important to understand how to obtain the most from the materials while maintaining the ability to print complex geometries effectively. Combining such a manufacturing method with advanced carbon materials, such as Graphene, Carbon Nanotubes, and Carbon fibers, with their mechanical and conductive properties, delivers a cutting-edge combination of low-cost conductive products. Through the process of printing the effectiveness of these properties decreases. Thorough optimization is required to determine the idealized ink functional and flow properties to ensure maximum printability and functionalities offered by carbon nanoforms. The optimization of these properties then is limited by the printability. By determining the physical properties of printability and flow properties of the inks, calculated compromises can be made for the ink design. In this review we have discussed the connection between the rheology of carbon-based inks and the methodologies for maintaining the maximum pristine carbon material properties.

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Section: Introductionmentioning

confidence: 99%

Rheological Issues in Carbon-Based Inks for Additive Manufacturing

et al. 2019

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“…The print quality is determined primarily by minimizing filament size, assuming the process is set up correctly to proceed in the four steps described previously. 5 , 6 , 8 This is because large filaments produce thick circular depositions in the area where they collapse, leading to an uneven print and reduced resolution. 6 The deposition height has been shown to depend very little on the squeegee speed and pressure; instead, it is highly dependent on the mesh geometry and, to a lesser degree, the ink composition and interaction with the substrate.…”

Section: Screen Printing Fundamentalsmentioning

confidence: 99%

“… 1 This requires the ink’s rheology to be optimized for the complicated fluid dynamics during screen printing and the surface chemistry at the ink–mesh and ink–substrate interface suitable to the printing mechanisms described in section 2 . 5 , 6 Second, the ink must be highly conductive and maintain this conductivity with strain up to 20% for wearable applications. 2 This requires a solid understanding of the nanomaterial–polymer matrix interactions that form the material’s percolation threshold.…”

Section: Introductionmentioning

confidence: 99%

“… 2 This requires a solid understanding of the nanomaterial–polymer matrix interactions that form the material’s percolation threshold. 5 − 7 Third, the resulting print must be durable through repeated strain over multiple uses, which is also controlled primarily by the particle dispersion and matrix composition. 2 Finally, the print width should be sufficiently thin (<100 μm) and precisely controlled to allow for reliable and small feature device fabrication.…”

Section: Introductionmentioning

confidence: 99%

“… 2 , 4 , 9 , 11 , 12 For each of these materials, finely controlling material properties and interparticle interactions during synthesis, particle dispersion, and polymer matrix composition allows for the delivery of high printability, conductivity, reliability, and resolution in a printable ink. 5 , 7 , 12 …”

Section: Introductionmentioning

confidence: 99%

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Advances in Screen Printing of Conductive Nanomaterials for Stretchable Electronics

2021

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Stretchable electronics have demonstrated tremendous potential in wearable healthcare, advanced diagnostics, soft robotics, and persistent human–machine interfaces. Still, their applicability is limited by a reliance on low-throughput, high-cost fabrication methods. Traditional MEMS/NEMS metallization and off-contact direct-printing methods are not suitable at scale. In contrast, screen printing is a high-throughput, mature printing method. The recent development of conductive nanomaterial inks that are intrinsically stretchable provides an exciting opportunity for scalable fabrication of stretchable electronics. The design of screen-printed inks is constrained by strict rheological requirements during printing, substrate–ink attraction, and nanomaterial properties that determine dispersibility and percolation threshold. Here, this review provides a concise overview of these key constraints and a recent attempt to meet them. We begin with a description of the fluid dynamics governing screen printing, deduce from these properties the optimal ink rheological properties, and then describe how nanomaterials, solvents, binders, and rheological agents are combined to produce high-performing inks. Although this review emphasizes conductive interconnections, these methods are highly applicable to sensing, insulating, photovoltaic, and semiconducting materials. Finally, we conclude with a discussion on the future opportunities and challenges in screen-printing stretchable electronics and their broader applicability.

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Roll stamped Ni/MWCNT composites for highly reliable cellulose paper-based strain sensor

et al. 2022

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Printing technology for electronic devices has received signi cant attention owing to its fast and massive productivity under ambient conditions. In this study, a facile approach was proposed for manufacturing cellulose paper-based strain sensors with Ni/ multi-walled carbon nanotubes (MWCNT) composites using roll stamping technology. This process enables fabrication of stable sensing structures owing to the formation of stable Ni core enveloping structures in the MWCNT interlacing network. In particular, the rheological properties of the composites revealed shear thinning and thixotropic behaviors, which resulted in ne printing of the sensing electrodes. Furthermore, the shape of the printed patterns, impacted by the pattern morphology, signi cantly in uenced the strain-sensing performance. In particular, the Ni/MWCNT composite-based strain sensor exhibited higher gauge factor of 13.9 with high sensing recovery of 90.4% and stability for 23,500 bending cycles test.

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The importance of shear thinning, thixotropic and viscoelastic properties of thick film pastes to predict effects on printing performance

Cited by 14 publications

References 10 publications

Rheological Issues in Carbon-Based Inks for Additive Manufacturing

Rheological Issues in Carbon-Based Inks for Additive Manufacturing

Advances in Screen Printing of Conductive Nanomaterials for Stretchable Electronics

Roll stamped Ni/MWCNT composites for highly reliable cellulose paper-based strain sensor

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