Betacel
Betacel is considered to be the first commercially successful betavoltaic battery. It was developed in the early 1970s by Larry C. Olsen at the American corporation McDonnell Douglas, using Promethium-147 radioisotope as the beta-electron source coupled to silicon semiconductor cells. This power source was incorporated in the Betacel-Biotronik heart pacemaker. The device was not widely adopted because of its limited lifespan and doubts over the use of radioactive material, but more recently betavoltaic batteries using non-radioactive substances have been developed for use in microelectronics.
The betavoltaic program along with the development of the Betacel was led by Dr. Olsen and a team of researchers at Donald W. Douglas Laboratories (DWDL), McDonnell Douglas Corporation, in the early 1970s. As the first (and only) viable betavoltaic power source ever developed, it was immediately used to power heart pacemakers. Betacel powered cardiac pacemakers were implanted in numerous patients in the 1970s. Biotronik GmbH & Co., Ingenieurburo, Berlin, adapted its chemical battery-powered pacemakers to accept the promethium-fueled Betacel battery. The Betacel powered Biotronik pacemakers were considered to have useful lives of 7 to 10 years. Clinical investigation of the Betacel-Biotronik pacemaker began in Europe in 1972 and was extended to the United States under State of Washington license in 1973. By early 1973, over 60 implanted Betacel-Biotronik pacemakers were being monitored as part of the clinical investigation. By mid-1974, the USAEC had authorized the licensing in the United States of a Clinical Investigation Program that allowed the implantation of 50 Betacel-Biotronik pacemakers per month in major clinics in the U.S.
Betacels utilized Pm-147 beta sources that were combined with custom designed silicon p-n junctions. Operational configurations involved stacking unidirectional sources with Si p-n junctions in a series arrangement. The power output of the Betacel was approximately 400 microWatts. The power density of the battery was approximately 0.025 milliWatts per cubic centimeter. The battery itself was approximately one cubic inch in volume (16 cm3). Most of the volume was used for shielding, to contain the gamma radiation that was emitted from the Pm-146 contaminant within the Pm-147.
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