Heart cell contractions measured using a micromachined polysilicon force transducer

1995 ◽  
Author(s):  
Gisela Lin ◽  
Kristofer S. J. Pister ◽  
Kenneth P. Roos
Keyword(s):  
Force Transducer ◽  
Heart Cell

Surface micromachined polysilicon heart cell force transducer

2000 ◽  
Vol 9 (1) ◽  
pp. 9-17 ◽  
Author(s):  
G. Lin ◽  
K.S.J. Pister ◽  
K.P. Roos
Keyword(s):  
Force Transducer ◽  
Heart Cell ◽  
Cell Force

Combined force and voltage measurement in rapidly superfused guinea pig heart cells

1990 ◽  
Vol 258 (4) ◽  
pp. C739-C748 ◽  
Author(s):  
N. Shepherd ◽  
V. J. Fisher
Keyword(s):  
Membrane Potential ◽  
Guinea Pig ◽  
Isometric Force ◽  
Force Transducer ◽  
Heart Cell ◽  
Heart Cells ◽  
Voltage Measurement ◽  
Guinea Pig Heart ◽  
Control Value ◽  
Voltage Follower

We describe the construction and use of a setup that allows the rapid exchange of the solution surrounding an isolated guinea pig heart cell while simultaneously measuring the isometric force and membrane potential (Em). Cells were stably attached, by means of poly-L-lysine, to a force transducer which was adapted from one previously used for a study of frog atrial cells [N. Shepherd and F. Kavaler.Am. J. Physiol. 251 (Cell Physiol. 20): C653-C661, 1986]. The modified transducer is simple to construct and use and can be readily added to existing patch-clamp setups. The strength of attachment of a cell to the transducer exceeded the strength of the gigaseal in all of the experiments. The membrane potential was measured by means of patch electrodes and a high-impedance voltage follower. Rapidly changing extracellular K concentration [( K]o) from 5.4 to 10.8 mM caused a positive change of Em by 16.5 +/- 1.4 mV with a half-time (t1/2) of 27 +/- 4 ms. Replacing calcium in the perfusate by magnesium instantly abolished the contraction and shortened the action potential. Twitch tension returned stepwise to the control value on return of calcium to the perfusate. Our initial observations show that the patch electrode can be used successfully in conjunction with the isometric force transducer and rapid extracellular solution changes for studies of excitation and contraction coupling in isolated mammalian heart cells.

Miniature heart cell force transducer system implemented in MEMS technology

2001 ◽  
Vol 48 (9) ◽  
pp. 996-1006 ◽  
Author(s):  
Gisela Lin ◽  
R.E. Palmer ◽  
K.S.J. Pister ◽  
K.P. Roos
Keyword(s):  
Force Transducer ◽  
Heart Cell ◽  
Mems Technology ◽  
Cell Force

Confocal imaging of calcium in intact ventricular muscle provides a new view of excitation-contraction coupling

1996 ◽  
Vol 54 ◽  
pp. 738-739
Author(s):  
W.G. Wier
Keyword(s):  
Local Control ◽  
Cardiac Tissue ◽  
Cell Function ◽  
Isolated Heart ◽  
Cardiac Cells ◽  
Confocal Imaging ◽  
Ion Concentration ◽  
Heart Cell ◽  
Free Calcium ◽  
Heart Cells

A fundamentally new understanding of cardiac excitation-contraction (E-C) coupling is being developed from recent experimental work using confocal microscopy of single isolated heart cells. In particular, the transient change in intracellular free calcium ion concentration ([Ca2+]i transient) that activates muscle contraction is now viewed as resulting from the spatial and temporal summation of small (∼ 8 μm3), subcellular, stereotyped ‘local [Ca2+]i-transients' or, as they have been called, ‘calcium sparks'. This new understanding may be called ‘local control of E-C coupling'. The relevance to normal heart cell function of ‘local control, theory and the recent confocal data on spontaneous Ca2+ ‘sparks', and on electrically evoked local [Ca2+]i-transients has been unknown however, because the previous studies were all conducted on slack, internally perfused, single, enzymatically dissociated cardiac cells, at room temperature, usually with Cs+ replacing K+, and often in the presence of Ca2-channel blockers. The present work was undertaken to establish whether or not the concepts derived from these studies are in fact relevant to normal cardiac tissue under physiological conditions, by attempting to record local [Ca2+]i-transients, sparks (and Ca2+ waves) in intact, multi-cellular cardiac tissue.

scholarly journals Enhanced Signal-to-Noise and Fast Calibration of Optical Tweezers Using Single Trapping Events

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 570
Author(s):  
Alexander B. Stilgoe ◽  
Declan J. Armstrong ◽  
Halina Rubinsztein-Dunlop
Keyword(s):  
Brownian Motion ◽  
Optical Tweezers ◽  
Optical Trap ◽  
Force Transducer ◽  
Signal To Noise ◽  
Likelihood Estimator ◽  
Micro Fluidics ◽  
Large Numbers ◽  
Force Reconstruction ◽  
Micron Particle

The trap stiffness us the key property in using optical tweezers as a force transducer. Force reconstruction via maximum-likelihood-estimator analysis (FORMA) determines the optical trap stiffness based on estimation of the particle velocity from statistical trajectories. Using a modification of this technique, we determine the trap stiffness for a two micron particle within 2 ms to a precision of ∼10% using camera measurements at 10 kfps with the contribution of pixel noise to the signal being larger the level Brownian motion. This is done by observing a particle fall into an optical trap once at a high stiffness. This type of calibration is attractive, as it avoids the use of a nanopositioning stage, which makes it ideal for systems of large numbers of particles, e.g., micro-fluidics or active matter systems.

An improved force transducer using amorphous ribbon cores

1981 ◽  
Vol 17 (6) ◽  
pp. 3376-3378 ◽  
Author(s):  
T. Meydan ◽  
M. Blundell ◽  
K. Overshott
Keyword(s):  
Amorphous Ribbon ◽  
Force Transducer

A miniature electrooptical force transducer

1988 ◽  
Vol 35 (2) ◽  
pp. 93-98 ◽  
Author(s):  
N. Maalej ◽  
J.G. Webster
Keyword(s):  
Force Transducer
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