Variable Stiffness
Variable Stiffness - Related Videos
07:45
Simple Polyacrylamide-based Multiwell Stiffness Assay for the Study of Stiffness-dependent Cell Responses
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Cited by 56 •
2015
Here, a method that enables quick, efficient, and inexpensive preparation of polyacrylamide gels in a multiwell plate format is described. The method does not require any specialized equipment and could be easily adopted by any research laboratory. It would be particularly useful in research focused on understanding stiffness-dependent cell responses.
05:45
Measuring the Bending Stiffness of Bacterial Cells Using an Optical Trap
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Cited by 9 •
2010
We present a protocol for bending filamentous bacterial cells attached to a cover-slip surface with an optical trap to measure the cellular bending stiffness.
10:31
Micropipette Aspiration of Substrate-attached Cells to Estimate Cell Stiffness
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Cited by 32 •
2012
Here we describe a quick and simple method to measure cell stiffness. The general principle of this approach is to measure membrane deformation in response to well-defined negative pressure applied through a micropipette to the cell surface. This method provides a powerful tool to study biomechanical properties of substrate-attached cells.
10:19
Studying the Effects of Matrix Stiffness on Cellular Function using Acrylamide-based Hydrogels
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Cited by 69 •
2010
The effect of substrata stiffness on cellular function can be modeled in vitro using polyacrylamide hydrogels of varying compliances.
01:27
Variables and Equations of State
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2026
The physical state of a pure substance can be defined by certain state variables such as volume (V), pressure (p), temperature (T), and amount of substance (n). When two gases are separated by a movable wall, the gas with the higher pressure naturally compresses the gas with the lower pressure. This causes the high-pressure gas to expand and the low-pressure gas to compress until both gases achieve mechanical equilibrium. At this point, their pressures equalize, and the movement of the wall...
FAQs
Pneumatic and hydraulic mechanisms use changes in pressure to alter how a structure resists deformation. Adjusting the pressure can move the device between more flexible and more rigid states, allowing its mechanical response to change during use. This approach is particularly relevant when a bioengineered system must conform to delicate anatomy and then provide greater support.
Jamming changes stiffness through the interaction of particles or layers, whereas shape-memory materials alter their form or mechanical behavior in response to a stimulus. Stimuli-responsive polymers similarly change their mechanical properties when exposed to inputs such as temperature. These mechanisms offer different routes for designing systems that adapt their deformation resistance.
Pressure and temperature can serve as control inputs because they influence the mechanical behavior of different variable-stiffness mechanisms. Pressure is associated with pneumatic, hydraulic, and jamming approaches, while temperature can affect shape-memory materials and stimuli-responsive polymers. Matching the input to the mechanism helps produce the intended transition between flexible and rigid behavior.
Selection depends on the required mechanical response and the available form of stimulation. Pneumatic or hydraulic actuation may suit systems controlled by pressure, while jamming, shape-memory materials, or stimuli-responsive polymers provide alternative ways to change stiffness. Engineers can then match the mechanism to needs such as anatomical conformity, load adaptation, or dynamic tissue modeling.
A soft robot can use a flexible state to conform to delicate anatomy, reducing the need for a consistently rigid structure during interaction. It can then increase resistance to deformation when additional support is needed. This combination of conformity and adjustable mechanical behavior makes variable stiffness relevant to bioengineered robotic systems.
Prosthetic and wearable devices experience changing loads during use, so a fixed mechanical response may not suit every condition. Variable stiffness allows these systems to adapt their resistance to deformation as loads change. In bioengineering, this adaptability can support devices designed to respond more appropriately to the user’s changing mechanical environment.
Tissue-engineering platforms can use variable stiffness to reproduce mechanical environments that change over time rather than remaining constant. By altering resistance to deformation through pressure, temperature, or other inputs, these systems can more closely represent dynamic biological conditions. This makes the approach relevant for platforms intended to model or support changing tissue environments.