Surface roughness measurements |
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Project lead
Alex McGhee
Alex McGhee
Papers published
Contact Measurements of Randomly Rough Surfaces
Bennett, A.I., Harris, K.L., Schulze, K.D. et al. Tribol Lett (2017) 65: 134. https://doi.org/10.1007/s11249-017-0918-5
Contact and Deformation of Randomly Rough Surfaces with Varying Root-Mean-Square Gradient
McGhee, A.J., Pitenis, A.A., Bennett, A.I. et al. Tribol Lett (2017) 65: 157. https://doi.org/10.1007/s11249-017-0942-5
Project overview
Many surfaces, both natural and synthetic, can be described as randomly rough, but rarely with a root-mean-square gradient as steep as g = 1. The selection of such a challenging surface parameter was intentional, but potentially limiting for broad comparisons across existing models and theories which may be limited by short angle approximations. By varying the root-mean-square gradients of the “Contact Mechanics Challenge” surface, and pressing each surface into contact with a PDMS elastic half space, contact measurements can be made in many conditions. In situ measurements of the real area of contact and contact-area distributions are performed using Frustrated Total Internal Reflectance (FTIR) along with surface deformation measurements performed using Digital Image Correlation (DIC). All of the loading is performed using a uniaxial load frame under force control. A Green’s Function Molecular Dynamics (GFMD) simulation for g = 1 is compared to all experimental data. The contact between PDMS and the 3D printed rough surface is measured in various loading rates, and surface conditions to obtain a complete understanding of how an elastic material responds to loading.
Contact Measurements of Randomly Rough Surfaces
Bennett, A.I., Harris, K.L., Schulze, K.D. et al. Tribol Lett (2017) 65: 134. https://doi.org/10.1007/s11249-017-0918-5
Contact and Deformation of Randomly Rough Surfaces with Varying Root-Mean-Square Gradient
McGhee, A.J., Pitenis, A.A., Bennett, A.I. et al. Tribol Lett (2017) 65: 157. https://doi.org/10.1007/s11249-017-0942-5
Project overview
Many surfaces, both natural and synthetic, can be described as randomly rough, but rarely with a root-mean-square gradient as steep as g = 1. The selection of such a challenging surface parameter was intentional, but potentially limiting for broad comparisons across existing models and theories which may be limited by short angle approximations. By varying the root-mean-square gradients of the “Contact Mechanics Challenge” surface, and pressing each surface into contact with a PDMS elastic half space, contact measurements can be made in many conditions. In situ measurements of the real area of contact and contact-area distributions are performed using Frustrated Total Internal Reflectance (FTIR) along with surface deformation measurements performed using Digital Image Correlation (DIC). All of the loading is performed using a uniaxial load frame under force control. A Green’s Function Molecular Dynamics (GFMD) simulation for g = 1 is compared to all experimental data. The contact between PDMS and the 3D printed rough surface is measured in various loading rates, and surface conditions to obtain a complete understanding of how an elastic material responds to loading.
Deformation measurements of carbomer |
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Project lead
Duy Nguyen
Alex McGhee
Duy Nguyen
Alex McGhee
Papers published
Full-Field Deformation Measurements in Liquid-like-Solid Granular Microgel Using Digital Image Correlation
McGhee, A., Bennett, A., Ifju, P. et al. Exp Mech (2018). https://doi.org/10.1007/s11340-017-0
Project overview
3D printing in yield stress materials are a recent advancement in the field of printing biological materials. The characterization of the yield stress material deformation due to a needle dragging through is important in the advancement of the manufacturing process. By showing how the printing space deforms due to a needle under various conditions, path planning strategies can be developed which account for past and future deformation to result in a more accurate finished part.
Full-Field Deformation Measurements in Liquid-like-Solid Granular Microgel Using Digital Image Correlation
McGhee, A., Bennett, A., Ifju, P. et al. Exp Mech (2018). https://doi.org/10.1007/s11340-017-0
Project overview
3D printing in yield stress materials are a recent advancement in the field of printing biological materials. The characterization of the yield stress material deformation due to a needle dragging through is important in the advancement of the manufacturing process. By showing how the printing space deforms due to a needle under various conditions, path planning strategies can be developed which account for past and future deformation to result in a more accurate finished part.
Dynamic deformation measurement within crosslinked hydrogel using DIC. |
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Project lead
Jack Famiglietti
Alex McGhee
Jack Famiglietti
Alex McGhee
Papers published
Dynamic deformation and strain measurements within PMMA due to contact with spherical probe
** experiments in progress**
Project overview
Debate among tribologists studying hydrogels concerning the ability of water within a crosslinked hydrogel to move thoughout the bulk of a material due to contact with a spherical probe. If the stresses within the hydrogel exceed the osmotic pressure of the gel, then then the movement of water through the material will dissipate some energy creating viscoelastic conditions. Here we aim to prove or disprove the hypothesis that the movement of water through the hydrogel explains the behavior of deformation due to dynamic contact.
Dynamic deformation and strain measurements within PMMA due to contact with spherical probe
** experiments in progress**
Project overview
Debate among tribologists studying hydrogels concerning the ability of water within a crosslinked hydrogel to move thoughout the bulk of a material due to contact with a spherical probe. If the stresses within the hydrogel exceed the osmotic pressure of the gel, then then the movement of water through the material will dissipate some energy creating viscoelastic conditions. Here we aim to prove or disprove the hypothesis that the movement of water through the hydrogel explains the behavior of deformation due to dynamic contact.
Immunosorbent assay development for 3D cell culture |
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Project lead
Alex McGhee
Alex McGhee
Papers published
In situ Spatiotemporal detection of cytokine concentration in 3D cell culture
** experiments in progress **
Project overview
Biological processes are exceedingly complex, often relying on a cascade of multiple inputs and outputs. The quantification of such signals is typically measured using supernatant (the liquid surrounding the cell) in a separate device. Measuring cellular communication in this way increases the sensitivity of the measurement, but loses the contextual meaning of the message and may disturb the cellular environment in the process. Using an off the shelf bead-based immunoassay in a confocal microscope allows researchers to continuously monitor protein concentration while observing interactions between various cell types as they occur. Dynamic cell response to environmental stress can be measured both by protein production and live imaging allowing for in vitro measurements of cellular cascades.
In situ Spatiotemporal detection of cytokine concentration in 3D cell culture
** experiments in progress **
Project overview
Biological processes are exceedingly complex, often relying on a cascade of multiple inputs and outputs. The quantification of such signals is typically measured using supernatant (the liquid surrounding the cell) in a separate device. Measuring cellular communication in this way increases the sensitivity of the measurement, but loses the contextual meaning of the message and may disturb the cellular environment in the process. Using an off the shelf bead-based immunoassay in a confocal microscope allows researchers to continuously monitor protein concentration while observing interactions between various cell types as they occur. Dynamic cell response to environmental stress can be measured both by protein production and live imaging allowing for in vitro measurements of cellular cascades.