THIS PROPOSAL IS ADDRESSED TO IMPROVEMENTS IN THE INTERNAL RECHARGEABLE BATTERIES FOR VENTRICULAR ASSIST SYSTEMS (VAS).

THIS PROPOSAL IS ADDRESSED TO IMPROVEMENTS IN THE INTERNAL RECHARGEABLE BATTERIES FOR VENTRICULAR ASSIST SYSTEMS (VAS).THE MAJOR GOAL OF THIS PROGRAM IS TO DEVELOP AN IMPLANTABLE BATTERY THAT IS SUITABLE FOR VAS BACKUP IN TERMS OF STORED ENERGY, POWER, WEIGHT, VOLUME, AND LONG-TERM DURABILITY. THE SPECIFIC REQUIREMENT FOR THE IMPLANTED BATTERY SYSTEM ISTO PROVIDE ABOUT 9 WATTS OF POWER FOR UP TO 30 MINUTES EACH DAY OVER A TWO-YEAR PERIOD. THIS TRANSLATES TO ABOUT 800 CYCLES AND 4.5 WH, CONFIGURED AS A 12 V BATTERY FOR PRACTI- CAL REASONS. ALL OF THE BATTERY POWERED SYSTEMS PRESENTLY UNDER DEVELOPMENT USE COMMERCIAL NICKEL-CADMIUM. AT THE TEMPERATURE THIS APPLICATION (37 TO 40 C), NI-CD CELLS SHOW ENERGY DENSITIES IN THE RANGE OF 13 TO 19 WH/KG. TO IMPROVETHE PERFORMANCE OF THE IMPLANTABLE BATTERY SYSTEM, DEVELOPMENT OF A AG/CD CELL IS PROPOSED. THIS SYSTEM EXHIBITS USABLE ENERGY DENSITIES OF 25 TO 50 WH/KG WITH POTENTIAL FOR BETTER CHARGE ACCEPTANCE AND EFFICIENCY AT 40 C. THE FOCUS OF THIS INVESTIGATION WILL BE IMPROVEMENT OF CYCLE LIFE. THE APPROACH IS BASED PRIMARILY ON THE REDUC- TION OF THE LEVEL OF DISSOLVED SILVER OXIDE, AND THE INTRO- DUCTION OF ADVANCED DEVELOPMENT INORGANIC SEPARATORS. THE PROGRAM ALSO SEEKS TO DEFINE PERFORMANCE OF THE AG-CD SYSTEMAT 40 C.