An optical fiber transducer for single myofibril force measurement

Fearn, Lisa A.; Bartoo, Marc L.; Myers, John A.; Pollack, Gerald H.

doi:10.1109/10.245630

Cited by 25 publications

(12 citation statements)

References 13 publications

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“…The frequency bandwidth and noise level (RMS) in our measurements were comparable to those of the other transducer methods [5,8,10,12,16,20]. Our transducer thus achieves better isometric conditions and a better frequency response.…”

Section: Discussionsupporting

confidence: 71%

A new transducer based on the evanescent field effect for high-resolution displacement and force measurements

Knobloch

Vögel

Fink

2000

Pflügers Arch - Eur J Physiol

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A new transducer, using the effect of frustrated total internal reflection of electromagnetic waves, was developed for displacement and force measurements in muscle research. The physical theory for this effect predicts the formation of an evanescent electromagnetic field in the gap between two separated optical surfaces. This evanescent electromagnetic field enables the transmission of light across the gap between the two media, an effect not contained in ray optics formalism. In the apparatus described here, the optical surfaces were obtained by bevelling 2 optical fibres to angles higher than the specific critical angle of the media used. Since the amount of transmitted light depends strongly on the distance between the surfaces, very small forces are detectable if one fibre is used as a cantilever. To test the transducer a small myofibrillar bundle (20 microm diameter) was mounted isometrically on it and contraction activated by release of "caged" Ca2+. Force and displacement steps of 180-220 nN and 9-11 nm respectively were measured with resolutions of 10 nN and 288 pm, respectively. From theoretical and practical considerations, it is expected that the presented principle will be able to achieve even much higher sensitivity for the determination of force (better than picoNewton) and distance (femtometre).

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Section: Discussionsupporting

confidence: 71%

A new transducer based on the evanescent field effect for high-resolution displacement and force measurements

Knobloch

Vögel

Fink

2000

Pflügers Arch - Eur J Physiol

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“…Force in the specimen is calculated from the lateral displacement in one of the wires. Measuring forces from cantilevered elements avoids drift, resolution and complexity issues associated with piezoelectric, strain gauge and electromagnetic sensors (Bouten et al, 2003;Miyazaki et al, 2000;Fearn et al, 1993).…”

Section: Methodsmentioning

confidence: 99%

“…Although methods exist for measuring the mechanical properties of individual cells (Evans, 1983;Miyazaki et al, 2000;Fearn et al, 1993) and bulk tissues (Abe et al, 1996), methods to obtain mechanical data from specimens of embryonic epithelium, which occur at a length scale between these two, have not previously been reported. Studies of embryonic tissues have been infrequent and, to date, have been limited to parallel plate compression tests of cell aggregates (Forgacs et al, 1998) and tensile tests of chick heart tissue (Miller et al, 1997).…”

Section: Introductionmentioning

confidence: 98%

Tensile properties of embryonic epithelia measured using a novel instrument

Wiebe

Brodland

2005

Journal of Biomechanics

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“…An experimental setup to measure SL and tension of single myofibrils has been developed, and is described in detail elsewhere Fearn et al, 1993;Linke et al, 1993). Briefly, the apparatus is centered around a Zeiss Axiovert 35 inverted microscope, equipped with phasecontrast optics.…”

Section: Experimental Apparatusmentioning

confidence: 99%

Limits of titin extension in single cardiac myofibrils

Linke

Bartoo

Ivemeyer

et al. 1996

J Muscle Res Cell Motil

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Passive force and dynamic stiffness were measured in relaxed, single myofibrils from rabbit ventricle over a wide range of sarcomere lengths, from approximately 2-5 microns. Myofibril stretch up to sarcomere lengths of approximately 3 microns resulted in a steady increase in both force and stiffness. The shape of the length-force and the length-stiffness curves remained fully reproducible for repeated extensions to a sarcomere length of approximately 2.7 microns. Above this length, myofibrillar viscoelastic properties were apparently changed irreversibly, likely due to structural alterations within the titin (connectin) filaments. Stretch beyond approximately 3 microns sarcomere length resulted in a markedly reduced slope of the passive force curve, while the stiffness curve became flat. Thus, cardiac sarcomeres apparently reach a strain limit near a length of 3 microns. Above the strain limit, both curve types frequently showed a series of inflections, which we assumed to result from the disruption of titin-thick filament bonds and consequent addition of previously bound A-band titin segments to the elastic I-band titin portion. Indeed, we confirmed in immunofluorescence microscopic studies, using a monoclonal antibody against titin near the A/I junction, that upon sarcomere stretch beyond the strain limit length, the previously stationary antibody epitopes suddenly moved into the I-band, indicating A-band titin release. Altogether, the passive force/stiffness-length relation of cardiac myofibrils was qualitatively similar to, but quantitatively different from, that reported for skeletal myofibrils. From these results, we inferred that cardiac myofibrils have an approximately two times greater relative I-band titin extensibility than skeletal myofibrils. This could hint at differences in the maximum passive force-bearing capacity of titin filaments in the two muscle types.

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An optical fiber transducer for single myofibril force measurement

Cited by 25 publications

References 13 publications

A new transducer based on the evanescent field effect for high-resolution displacement and force measurements

A new transducer based on the evanescent field effect for high-resolution displacement and force measurements

Tensile properties of embryonic epithelia measured using a novel instrument

Limits of titin extension in single cardiac myofibrils

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