Indentation fracture of silicone gels

Lin, Wei Chun; Otim, Kathryn J.; Lenhart, Joseph L.; Cole, Phillip J.; Shull, Kenneth R.

doi:10.1557/jmr.2009.0128

Cited by 12 publications

(22 citation statements)

References 27 publications

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“…The fangs tested here have evolved to puncture a range of different tissues, varying with prey type, which may be more deformable than the ballistics gel used in our experiment. Such a target will interact with a greater portion of the tool before puncture occurs, and the overall morphology of the puncturing tool will be of greater importance [43]. Moreover, the speed at which force is applied will affect the energy being imparted to the system, as well as the material properties of the target, both of which are relevant to the puncture mechanics [34,39].…”

Section: Discussionmentioning

confidence: 99%

How do morphological sharpness measures relate to puncture performance in viperid snake fangs?

Crofts

Lai

et al. 2019

Biol. Lett.

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It makes intuitive sense that you need a sharp tool to puncture through a tough material. The typical approach to evaluating sharpness in biological puncturing tools is to treat morphological measurements as a proxy for puncture ability. However, there are multiple approaches to measuring sharpness, and the relative influence of morphology on function remains unclear. Our goal is to determine what aspects of tip morphology have the greatest impact on puncture ability, using ( a ) viper fangs and ( b ) engineered punches to isolate the effects of different sharpness measures. Our results indicate that tip included angle is the strongest predictor of puncture performance in both viper fangs and engineered punches. For puncture tools with small included angles, sharpness index (based on the radius of curvature) also affects puncture ability. Finally, we found that punches serve as good predictors of fang performance at small angles and sharpness index values.

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Section: Discussionmentioning

confidence: 99%

How do morphological sharpness measures relate to puncture performance in viperid snake fangs?

Crofts

Lai

et al. 2019

Biol. Lett.

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“…Mechanical indentation testing and rheological characterization was used to evaluate the mechanical and kinetic gel formation properties for PBSA and TBSA hydrogels. , The elastic modulus of PBSA gels (46 kPa) were also different from those of TBSA gels (67 kPa), the latter being more stiff. Similar cross-linked 15 wt % TBSA type-hydrogels using 10 mM genipin at 60 °C have been reported to have a moduli between 60 and 100 kPa which is consistent with our results .…”

Section: Discussionmentioning

confidence: 99%

“…A custom built microindenter (Shull Group, Northwestern University, IL) was used to measure the Young’s modulus of BSA gels. 36 A flat-ended cylindrical stainless steel punch with a radius a = 0.44 mm was used to indent the surface of the gel with a Burleigh inchworm motor (Rochester, NY) attached to a Sensotec 1 kg load cell (Columbus, OH), while the displacement was measured with a Philtec optical displacement sensor (Annapolis, MD). As the probe indented the sample at a fixed rate (10 μm/s), the load was recorded on a computer.…”

Section: Methodsmentioning

confidence: 99%

Albumin Hydrogels Formed by Electrostatically Triggered Self-Assembly and Their Drug Delivery Capability

Baler

Michael²,

Szleifer³

et al. 2014

Biomacromolecules

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Biological hydrogels are fundamentally biocompatible and have intrinsic similarities to extracellular matrices in medical applications and drug delivery systems. Herein we demonstrate the ability to form drug-eluting protein hydrogels using a novel mechanism that involves the electrostatically triggered partial denaturation and self-assembly of the protein via changes in pH. Partial denaturation increases the protein’s solvent exposed hydrophobic surface area, which then drives self-assembly of the protein into a hydrogel within 10 min at 37 °C. We describe the properties of an albumin hydrogel formed by this mechanism. Intrinsic drug binding properties of albumin to all-trans retinoic acid (atRA) are conserved through the partial denaturation process, as confirmed by fluorescence quenching. atRA released from the hydrogel inhibited smooth muscle cell migration as per an in vitro scratch wound assay. Atomistic molecular dynamics and potential of mean force calculations show the preservation and potential creation of new atRA binding sites with a binding energy of −41 kJ/mol. The resulting hydrogel is also biocompatible and exhibits rapid postgelation degradation after its implantation in vivo. This interdisciplinary work provides a new tool for the development of biocompatible protein hydrogel drug delivery systems.

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“…Modulus values were calculated from the equation [10] : Hence we characterized the gel in compression by a flat punch indentation technique.…”

Section: Materials and Preparationmentioning

confidence: 99%

Fiber-reinforced Hydogels for Soft Tissue Replacement

Agrawal

Calvert

2009

MRS Proc.

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Synthetic hydrogels have poor mechanical properties that limit their use in load bearing applications. In contrast, biological hydrogels are tough and strong due to reinforcement with nano to micron size fibers. Our work is focused on designing new class of hydrogel assemblies based on fiber reinforced hydrogel composites. In analogy to the spinning of a spider web, a pultrusion system was developed to spin micron-diameter polymer fibers from solution in order to build predefined three dimensional patterned fiber-reinforced hydrogel structures. The gel chemistry is based on epoxy-amine crosslinking. We have formulated various epoxy-amine gels with swellability ranges from 0% to 1000% in water. The fibrous reinforcement affects the swelling and mechanical properties of the gel. For mechanical characterization flat punch probe indentation technique was performed. The effect of fiber density and extent of swelling on the reinforcement of epoxy matrix is investigated. Based on a better understanding of fiber reinforcement of gels, we hope to be able to design strong gels for biomedical devices and soft machines.

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Indentation fracture of silicone gels

Cited by 12 publications

References 27 publications

How do morphological sharpness measures relate to puncture performance in viperid snake fangs?

How do morphological sharpness measures relate to puncture performance in viperid snake fangs?

Albumin Hydrogels Formed by Electrostatically Triggered Self-Assembly and Their Drug Delivery Capability

Fiber-reinforced Hydogels for Soft Tissue Replacement

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