ABSTRACT
We have designed, built and tested an experimental apparatus for in vitro performance testing of an artificial urinary sphincter. A simulated urinary tract delivered a simulated urine to either an excised porcine urethra or artificial urethra at a physiologically normal pressure range of 0-93 cm H2O (0-9.12 kPa) and flow rate range of 0-830 ml/min (0-1.38 x 10(-5) m3/s). Inlet urine pressure, sphincter temperatures at several locations, urine flow, differential pressure across the urethra, and linear motion of the sphincter were measured with appropriate transducers and recorded on a PC-based data acquisition system. We conclude that the simulated urinary tract is adequate for testing artificial sphincter performance and that the data acquisition system accurately measures, displays, and records the parameters which indicate system performance.
Subject(s)
Artificial Organs , Models, Biological , Urethra , Animals , Bioprosthesis , Evaluation Studies as Topic , Prosthesis Design , Swine , Urination , UrodynamicsABSTRACT
The electrical properties of implantable ceramics have been studied. The properties of resistivity, dielectric constant, magnetic permeability, and piezoelectric constant were measured using test methods developed to give reproducible results on common electrical instruments. The electrical properties of Aluminum Calcium Phosphorus Oxide (ALCAP) and Zinc Calcium Phosphorus Oxide (ZCAP) ceramics were measured with an ohmeter, impedance bridge, and oscilloscope in conjunction with special test fixtures. Both the ALCAP and ZCAP materials were characterized as insulating dielectrics with mean resistivities of 6.0E04 ohm.m and with mean dielectric constants of 5.3 for both ceramics. Neither the ALCAP nor the ZCAP exhibited magnetic or piezoelectric properties. The results indicate that these ceramics could be used as an insulative housing for a variety of medical devices.
