Millimeter-scale radioluminescent power for electronic sensors
Averal N. Kandala,
Sinan Wang,
Joseph E. Blecha,
Yung-Hua Wang,
Rahul K. Lall,
Ali M. Niknejad,
Youngho Seo,
Michael J. Evans,
Robert R. Flavell,
Henry F. VanBrocklin,
Mekhail Anwar
Affiliations
Averal N. Kandala
Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA 94720, USA; Corresponding author
Sinan Wang
Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94107, USA
Joseph E. Blecha
Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94107, USA
Yung-Hua Wang
Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94107, USA
Rahul K. Lall
Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA 94720, USA
Ali M. Niknejad
Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA 94720, USA
Youngho Seo
Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94107, USA
Michael J. Evans
Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94107, USA
Robert R. Flavell
Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94107, USA
Henry F. VanBrocklin
Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94107, USA
Mekhail Anwar
Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA 94158, USA; Corresponding author
Summary: The storage and generation of electrical energy at the mm-scale is a core roadblock to realizing many untethered miniature systems, including industrial, environmental, and medically implanted sensors. We describe the potential to address the sensor energy requirement in a two-step process by first converting alpha radiation into light, which can then be translated into electrical power through a photovoltaic harvester circuit protected by a clear sealant. Different phosphorescent and scintillating materials were mixed with the alpha-emitter Th-227, and the conversion efficiency of europium-doped yttrium oxide was the highest at around 2%. Measurements of the light generated by this phosphor when combined with Th-227 reveal that over 100 nW of optical power can be expected at volumes around 1 mm3 over more than two months. The use of a clear sealant, together with the evaporation of liquid solution following the mixture, can enable safe miniaturization for size-constrained medical and internet-of-things (IoT) sensor applications.
