Wikipedia
Betacel is considered to be the first successfully commercialized betavoltaic battery. It was created with the use of Promethium-147 radioisotope as the beta-electron source and was coupled to silicon semiconductor cells. The betavoltaic program along with the development of the Betacel was led by Dr. Larry C. 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.
During that same time period, there was a certain stigma associated with the use of nuclear power and radioactive materials; the public was genuinely fearful and leery of any nuclear technology. This stigma, combined with advances in (and the lower cost of) Lithium-Ion battery technology eventually overshadowed aspirations of a more lucrative future for the Betacel, relegating betavoltaic batteries to the realm of academic research in the years that immediately followed.
The Betacel did not last but it provided a foundation for future betavoltaic technology research and sparked a resurgence of interest in betavoltaic power generation. Between 2001 and 2010, four commercial companies (City Labs, Inc., BetaBatt Inc., Qynergy, Inc. and Widetronix, Inc.) have ventured into betavoltaic power cell development, while university research on the subject is still actively being conducted. Rapid advances in semiconductor and materials science technology, integrated circuit design and fabrication, and micro- / nano-scale micro-electromechanical systems (MEMS), have converged to the extent that extremely small devices with diminutive power requirements are becoming more and more routine. These devices are ideally suited for carefully thought-out betavoltaic power solutions that can easily and safely offer nanoWatt-to-microWatt power levels with enduring 20-year lifetimes.