AJP - Heart and Circulatory Physiology, Vol 247, Issue 5 857-H860, Copyright © 1984 by American Physiological Society
A hermetically sealed cardiac dimension transducer for long-term animal implantation
C. O. Olsen, S. J. Abert, D. D. Glower, J. A. Spratt, G. S. Tyson, J. W. Davis and J. S. Rankin
Pulse transit sonomicrometry is a well-accepted method for assessing
cardiac dimensions and function in research animals. Unfortunately, this
technique has been hampered in chronic applications by a significant
incidence of transducer failure secondary to leakage of corrosive
biological fluids into the piezoelectric material. The fluid leakage
generally occurred at the interface between the encapsulating epoxy and the
bioelectric cable and resulted in progressive functional deterioration with
time. In this paper, a new hemispheric ultrasonic dimension transducer is
described with a mechanical hermetic seal at the bioelectric
cable-transducer interface. The hermetically sealed transducers withstood
400 psi compressed air without leakage, while conventional transducers
routinely leaked at 60 psi. The performance characteristics of the new
transducers were similar to those previously reported with omnidirectional
designs, and no failures have occurred during 3 yr of experience with
repeated transducer implantations.
