Non-invasive Force Measurement Research Articles

Non-Invasive Force Measurement Based on Magneto-Elastic Effect for Steel Wire Ropes

Force measurement on steel wire rope (SWR) is significant to ensure the safety of people and property. Previous methods propose the electro-magnetic sensor, which measures the force applied on the SWR non-invasively and does not damage the structure of the SWR. Based on the magneto-elastic effect and integration of induction voltage as the indicator, electro-magnetic sensors perform well in many situations. However, in practice, the integration of induction voltage method is noise-sensitive, because the noise is easily accumulated by integration in the practical environment. In this case, we propose an improved method based on a novel indicator, maximal induction voltage. The maximal induction voltage method is influenced less by noise, as no integration of noise term is involved, so the maximal induction voltage method has better performance on noise reduction. Moreover, the paper builds a force measurement system by deriving the analytical linear relation between force and maximal induction voltage, and this linear relation can be estimated by prior experimental data. The experimental results show that the proposed method has higher linearity and sensitivity than the integration of induction voltage method.

Investigation of multiple-dynein transport of melanosomes by non-invasive force measurement using fluctuation unit \u03c7

Pigment organelles known as melanosomes disperse or aggregate in a melanophore in response to hormones. These movements are mediated by the microtubule motors kinesin-2 and cytoplasmic dynein. However, the force generation mechanism of dynein, unlike that of kinesin, is not well understood. In this study, to address this issue, we investigated the dynein-mediated aggregation of melanosomes in zebrafish melanophores. We applied the fluctuation theorem of non-equilibrium statistical mechanics to estimate forces acting on melanosomes during transport by dynein, given that the energy of a system is related to its fluctuation. Our results demonstrate that multiple force-producing units cooperatively transport a single melanosome. Since the force is generated by dynein, this suggests that multiple dyneins carry a single melanosome. Cooperative transport has been reported for other organelles; thus, multiple-motor transport may be a universal mechanism for moving organelles within the cell.

Investigation of Multiple-Dynein Transport of Melanosomes by Non-Invasive Force Measurement using the Fluctuation Theorem

Pigment organelles known as melanosomes disperse or aggregate in a melanophore in response to hormones. These movements are mediated by the microtubule motors kinesin-2 and cytoplasmic dynein. However, the force generation mechanism of dynein, unlike that of kinesin, is not well understood. In this study, to address this issue, we investigated the dynein-mediated aggregation of melanosomes in zebrafish melanophores. We applied the fluctuation theorem of non-equilibrium statistical mechanics [1,2,3] to estimate forces acting on melanosomes during transport by dynein, given that the energy of a system is related to its fluctuation. Our results demonstrate that multiple force-producing units cooperatively transport a single melanosome [4]. Since the force is generated by dynein, this suggests that multiple dyneins carry a single melanosome. Cooperative transport has been reported for other organelles; thus, multiple-motor transport may be a universal mechanism for moving organelles within the cell. [1] K. Hayashi, Biophys. Rev. https://doi.org/10.1007/s12551-018-0440-5 (2018). [2] K. Hayashi, S. Hasegawa, T. Sagawa, S. Tasaki and S. Niwa, Chem. Phys. Che. Phys. 20, 3404-3410 (2018). [3] K. Hayashi, S. Tsuchizawa, M. Iwaki and Y. Okada, MBoC, in press (2018). [4] S. Hasegawa, T. Sagawa, K. Ikeda, Y. Okada and K. Hayashi, preprint http://arxiv.org/abs/1808.03469

Application of the fluctuation theorem for noninvasive force measurement in living neuronal axons.

Although its importance is recently widely accepted, force measurement has been difficult in living biological systems, mainly due to the lack of the versatile noninvasive force measurement methods. The fluctuation theorem, which represents the thermodynamic properties of small fluctuating nonequilibrium systems, has been applied to the analysis of the thermodynamic properties of motor proteins in vitro. Here we extend it to the axonal transport (displacement) of endosomes. The distribution of the displacement fluctuation had three or four distinct peaks around multiples of a unit value, which the fluctuation theorem can convert into the drag force exerted on the endosomes. The results demonstrated that a single cargo vesicle is conveyed by one to three or four units of force production.

Non-invasive force measurement reveals the number of active kinesins on a synaptic vesicle precursor in axonal transport regulated by ARL-8.

Kinesin superfamily protein UNC-104, a member of the kinesin-3 family, transports synaptic vesicle precursors (SVPs). In this study, the number of active UNC-104 molecules hauling a single SVP in axons in the worm Caenorhabditis elegans was counted by applying a newly developed non-invasive force measurement technique. The distribution of the force acting on a SVP transported by UNC-104 was spread out over several clusters, implying the presence of several force-producing units (FPUs). We then compared the number of FPUs in the wild-type worms with that in arl-8 gene-deletion mutant worms. ARL-8 is a SVP-bound arf-like small guanosine triphosphatase, and is known to promote unlocking of the autoinhibition of the motor, which is critical for avoiding unnecessary consumption of adenosine triphosphate when the motor does not bind to a SVP. There were fewer FPUs in the arl-8 mutant worms. This finding indicates that a lack of ARL-8 decreased the number of active UNC-104 motors, which then led to a decrease in the number of motors responsible for SVP transport.

A novel method to determine perineal artery occlusion among male bicyclists.

Background. Perineal pressure due to bicycle riding has been associated with erectile dysfunction. We developed a novel method to measure the occlusive force exerted over the perineal arteries and determined perineal artery occlusion by a variety of seat designs.Methods. Doppler ultrasonography facilitated perineal artery localization and determination of the force required for perineal artery occlusion in 20 healthy men. Flexiforce® sensors were affixed over the proximal and distal aspects of the perineal arteries bilaterally. Individuals completed bicycle rides in the road- and stationary-settings with six distinct seat designs, including those with and without an anterior “nose.”Results. The occlusion time proportion of the total ride time was calculated for each trial. The overall occlusion time proportion was 0.59 (95% CI [0.45–0.73]) across all seats and settings. The “no-nose” bicycle seat and the stationary-setting demonstrated significantly lower occlusion proportion times than the traditional nose bicycle seat and road-setting, respectively. However, all bicycle seats yielded an occlusion time proportion of 0.41 or greater.Discussion. Our method of real-time, non-invasive force measurement localized to the perineal arteries may be used to validate future bicycle seat design. It also underscores the significant risk of perineal artery insufficiency in men who are avid bicyclists. This risk may be minimized by using newer “no-nose” bicycle seats.

FLOW VELOCIMETRY FOR WEAKLY CONDUCTING ELECTROLYTES BASED ON HIGH RESOLUTION LORENTZFORCE MEASUREMENT

We demonstrate that a flow velocity measurement can be transformed into a non-invasive force measurement by metering the dragforce acting on a system of magnets that is arranged around a flow channel. This method is called Lorentzforce velocimetry and has been developed in the last years in our institute. It is a highly feasible principle for materials with large conductivity like liquid metals. To evolve this method for weakly conducting fluids like salt water or molten glass the dragforce measurement is the challenging bottleneck. Here forces of 10−8 and less of the weightforce of the magnet system have to be resolved in the rather noisy environment of the flow channel. In this paper different force measurement techniques get tested and compared. In the first setup the drag-force is acting on the magnets that are hanging as a pendulum with 0.5 m long wires on a mounting. Here the displacement in the range of a few μm can be detected with a laser interferometer and another optical positioning sensor. For the second setup the magnet system is attached to a state of the art electromagnetic force compensation balance. The balance is used in an unusual orientation: It is turned by 90 degrees to measure the horizontally acting Lorentzforce. Different ways of getting the correct force signal out of the two measurement setups will be presented and discussed. For generalization of the measurement principle the Lorentzforce is determined for different fluid profiles. In addition to that we have developed new systematic noise reduction methods to increase the resolution of both force measurement techniques by a factor of ten or larger which we will present here.