Constant Force Clamping
Constant Force Clamping - Related Videos
00:57
Power Expended by a Constant Force
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2023
The relationship between work done and the time taken to do it can be explained using the concept of power. For example, several sprinters in a race may have the same velocity when they reach the finish line, therefore doing the same amount of work, but the winner does it in the least amount of time. Thus, power is defined as the rate of doing work. Since work can vary as a function of time, the average power is defined as the work done during a time interval, divided by the time interval.
08:48
Stretching Short Sequences of DNA with Constant Force Axial Optical Tweezers
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Cited by 5 •
2011
We illustrate the use of a constant force axial optical tweezers to explore the mechanical properties of short DNA molecules. By stretching DNA axially, we minimize steric hindrances and artifacts arising in conventional lateral manipulation, allowing us to study DNA molecules as short as ~100 nm.
11:23
Material Constants
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2023
Source: Roberto Leon, Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA In contrast to the production of cars or toasters, where millions of identical copies are made and extensive prototype testing is possible, each civil engineering structure is unique and very expensive to reproduce (Fig.1). Therefore, civil engineers must extensively rely on analytical modeling to design their structures. These models are simplified abstractions of reality and are used to...
08:10
Molecular Spring Constant Analysis by Biomembrane Force Probe Spectroscopy
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Cited by 6 •
2021
A biomembrane force probe (BFP) is an in situ dynamic force spectroscopy (DFS) technique. BFP can be used to measure the spring constant of molecular interactions on living cells. This protocol presents spring constant analysis for molecular bonds detected by BFP.
09:55
Force-Clamp Rheometry for Characterizing Protein-based Hydrogels
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Cited by 11 •
2018
A new force-clamp rheometry technique is used to investigate the mechanical properties of low-volume protein-based hydrogel samples tethered between a voice-coil motor and a force sensor. An analog proportional-integral-derivative (PID) system allows for the 'clamping' of the force experienced to the desired protocol.
FAQs
The feedback loop compares measured force with a selected set point. When the values diverge, the system adjusts the actuator or sample position. This arrangement keeps force near the target even as sample length, position, or molecular state changes. Consequently, changes in extension or molecular behavior can be interpreted under sustained mechanical loading rather than unintended changes in applied force.
The force sensor supplies the measurement that indicates whether the applied load matches the chosen set point. The actuator, or an equivalent adjustment of sample position, responds through the feedback system to correct deviations. Their coordinated operation makes it possible to follow biological responses while maintaining the mechanical condition needed for quantitative measurements.
Separating force from displacement allows researchers to observe how a biological structure changes while the applied load remains nearly fixed. This distinction is important because length or position may continue changing during molecular or cellular responses. The resulting measurements can reveal time-dependent behavior, including unfolding, bond lifetimes, motor activity, or viscoelastic responses.
A fixed-position approach emphasizes maintaining geometry, whereas constant force clamping emphasizes maintaining the applied mechanical load. Under clamping, the sample can change length or position while feedback adjusts the system to preserve force. This makes the technique suited to questions about responses to sustained stress rather than only responses at a fixed displacement.
A typical workflow begins by selecting the force set point and placing the biological sample in the measurement system. The force sensor then records the applied load while the feedback system compares it with the target. The actuator or sample position is adjusted as needed, allowing researchers to track changes in length, position, or molecular state over time.
The approach supports measurements of protein unfolding, receptor-ligand bond lifetimes, and molecular motor activity. It can also examine viscoelastic behavior in cells or tissues, where mechanical responses evolve over time. These applications use the same controlled-load principle but focus on different biological structures and outcomes, from molecular transitions to larger-scale material behavior.
Constant force clamping provides a way to relate sustained mechanical stress to biological change. At the molecular level, it can connect force with unfolding, binding lifetimes, or motor activity. In cells and tissues, it can characterize time-dependent viscoelastic behavior. Together, these measurements support quantitative mechanobiology by linking applied load with structural and functional responses.