TY - JOUR
T1 - Null-Balance Transducer for Isometric Force Measurements and Length Control of Single Heart Cells
AU - Luo, Ching Hsing
AU - Tung, Leslie
PY - 1991/12
Y1 - 1991/12
N2 - Recently, an ultrasensitive, optical-fiber-based force transducer was developed to measure the microscopic force of contraction of single heart cells. Since force in cardiac muscle is length and velocity dependent, it is desirable to maintain a constant (isometric) cell length. The original design permits ∼ 1% shortening of cell length to occur during twitch contractions. The shortening can be reduced significantly by adding a piezoelectric bimorph actuator and closed-loop control, as described in this paper. As a result, the effective stiffness of the transducer can be increased by a factor of about 100, and cell shortening reduced to -0.01%. For the force probes typically used, this is equivalent to a movement of less than 20 nm for a typical value of 100 nN peak cell force in single frog ventricular cells. The gain in stiffness is obtained without sacrificing sensitivity, although at the expense of frequency response. The new design also permits control of cell length and is applicable to studies of the mechanical stiffness of cardiac cells.
AB - Recently, an ultrasensitive, optical-fiber-based force transducer was developed to measure the microscopic force of contraction of single heart cells. Since force in cardiac muscle is length and velocity dependent, it is desirable to maintain a constant (isometric) cell length. The original design permits ∼ 1% shortening of cell length to occur during twitch contractions. The shortening can be reduced significantly by adding a piezoelectric bimorph actuator and closed-loop control, as described in this paper. As a result, the effective stiffness of the transducer can be increased by a factor of about 100, and cell shortening reduced to -0.01%. For the force probes typically used, this is equivalent to a movement of less than 20 nm for a typical value of 100 nN peak cell force in single frog ventricular cells. The gain in stiffness is obtained without sacrificing sensitivity, although at the expense of frequency response. The new design also permits control of cell length and is applicable to studies of the mechanical stiffness of cardiac cells.
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U2 - 10.1109/10.137282
DO - 10.1109/10.137282
M3 - Article
C2 - 1774078
AN - SCOPUS:0026318699
SN - 0018-9294
VL - 38
SP - 1165
EP - 1174
JO - IRE transactions on medical electronics
JF - IRE transactions on medical electronics
IS - 12
ER -