Forces between a stiff and a soft surface

Butt, Hans‐Jürgen; Pham, Jonathan T.; Kappl, Michael

doi:10.1016/j.cocis.2016.09.007

Cited by 22 publications

(18 citation statements)

References 80 publications

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“…These elastomers are also common in fundamental research on soft matter physics and mechanics. For example, studies on soft adhesion, wetting, cavitation, and cell–surface interactions frequently implement PDMS as a model material. PDMS is used because it is commercially available (e.g., Sylgard 184), easy to prepare, and easy to tune the elastic modulus from a few megapascal down to a few kilopascal .…”

Section: Introductionmentioning

confidence: 99%

Extracting uncrosslinked material from low modulus sylgard 184 and the effect on mechanical properties

Glover

McLaughlin

McFarland

et al. 2020

Journal of Polymer Science

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Commercial silicone elastomers are commonly used in soft materials research due to their easily tunable mechanical properties.However, conventional polydimethylsiloxane (PDMS) elastomers with moduli below $100 kPa contain uncrosslinked free molecules, which play a significant role in their behavior. To utilize these materials, it is important to quantify what role these free molecules play in the mechanical response before and after their removal. We present a simple and inexpensive extraction method that enables the removal of free molecules from a lightly crosslinked sheet of Sylgard 184, a commercially available PDMS elastomer. The materials can contain a majority of free molecules yet maintain a thin and flat geometry without fractures after extraction. Subsequently, we compare the modulus, maximum stretchability, and hysteresis behavior with mixing ratios ranging from 60:1 to 30:1, before and after extraction. We show that the modulus, maximum stretchability, and dissipation increase upon extraction. Moreover, our approach offers a route to prepare crosslinked silicone elastomers with a modulus as low as $20 kPa without free molecules from a commercially available kit.

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Section: Introductionmentioning

confidence: 99%

Extracting uncrosslinked material from low modulus sylgard 184 and the effect on mechanical properties

Glover

McLaughlin

McFarland

et al. 2020

Journal of Polymer Science

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“…The Conpokal technique was first implemented in a non-biological polymer system, where the goal was to determine the adhesion, elasticity, and surface tension of hard surfaces in contact with soft surfaces. Confocal images provided a visual rendering of how the polymer deforms, adheres, and releases from the hard probe 1 , 2 . From polymers to biological samples, this technique provides the opportunity for near simultaneous live cell or microorganism confocal imaging and AFM.…”

Section: Introductionmentioning

confidence: 99%

“…AFM has been further adapted for microrheology 32 , 33 , frequency modulation 34 , 35 , and creep 25 , 36 , 37 experiments to study the viscoelastic properties of various cell lines. The use of an appropriate nanocontact model is critical to the extraction of quantitative elasticity values from AFM-produced force indentation measurements 1 , 2 . AFM studies that investigate the influence of cytoskeletal drugs on cell elasticity have shown the elastic modulus to be highly affected 38 .…”

Section: Introductionmentioning

confidence: 99%

Near Simultaneous Laser Scanning Confocal and Atomic Force Microscopy (Conpokal) on Live Cells

Sandin

Aryal

Wilkop

et al. 2020

JoVE

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Techniques available for micro-and nano-scale mechanical characterization have exploded in the last few decades. From further development of the scanning and transmission electron microscope, to the invention of atomic force microscopy, and advances in fluorescent imaging, there have been substantial gains in technologies that enable the study of small materials. Conpokal is a portmanteau that combines confocal microscopy with atomic force microscopy (AFM), where a probe "pokes" the surface. Although each technique is extremely effective for the qualitative and/or quantitative image collection on their own, Conpokal provides the capability to test with blended fluorescence imaging and mechanical characterization. Designed for near simultaneous confocal imaging and atomic force probing, Conpokal facilitates experimentation on live microbiological samples. The added insight from paired instrumentation provides co-localization of measured mechanical properties (e.g., elastic modulus, adhesion, surface roughness) by AFM with subcellular components or activity observable through confocal microscopy. This work provides a step by step protocol for the operation of laser scanning confocal and atomic force microscopy, simultaneously, to achieve same cell, same region, confocal imaging, and mechanical characterization.

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“…Firstly, the indentation depths need to be much smaller than the particle and indenter radii to ensure that linear poroelastic theory applies. Secondly, the velocity of the probe as it approaches and indents the particle needs to be fast enough such that negligible solvent has drained from the particle during approach after contact, but slow enough such that elastohydrodynamic effects due to film drainage coupled with deformation [26][27][28][29] do not contribute significantly to solvent drainage during approach. Thirdly, the measurement requires accurate estimates of the indentation contact area, and adhesion between the probe and the material can introduce significant deviations from the oft-assumed elastic contact 30 .…”

Section: Introductionmentioning

confidence: 99%