Harnessing Alpha Radiation to Power Miniaturized Implantable Medical Devices

Averal Kandala

EECS Department
University of California, Berkeley
Technical Report No. UCB/EECS-2025-17
May 1, 2025

http://www2.eecs.berkeley.edu/Pubs/TechRpts/2025/EECS-2025-17.pdf

Implantable medical devices (IMDs) have the potential to revolutionize medical diagnostics and therapy, as they provide an avenue for care providers to receive automatic feedback on the state of the patient’s body on timescales greatly accelerated from the appointment-based paradigm of today. However, three main challenges present themselves when we consider how best to integrate IMDs with the patient’s physiology without compromising on quality of life: scalability, longevity, and convenience.

The critical factor limiting progress on all three of these frontiers is power. Although research on novel battery technologies is ongoing, commercially-available batteries simply cannot provide sufficiently long-lasting power at the scales required for most chronic diagnostic sensing applications [9, 12], and alternative “independent” power strategies either carry short lifetimes or cannot be miniaturized [41]. In the absence of a proven miniaturized independent power source, research in the last decade has focused on the development of discontinuous powering models that rely on an external device, called the “interrogator”, to beam in power for harvesting by a receiver on the implant and establish a channel for communication with the implant [7, 38, 43, 44]. Ultrasound has emerged as the most promising such model due to its low attenuation in tissue and high time-averaged intensity limit as outlined by the FDA [7, 43, 44].

However convenient this type of model might be for enabling design miniaturization, it fails in general to deliver system-level convenience from the perspective of the patient, as the interrogator typically must be optimally aligned with the implant to ensure correct operation [31]. In addition, the implant simply cannot operate when it is not receiving power from the interrogator, limiting the diagnostic applicability of these models.

In order to develop the miniaturized independent power source that would overcome these challenges, this work presents a strategy for converting the energy of alpha radionuclides into light for harvesting by a physically surrounding photovoltaic structure. By using phosphorescent materials to achieve this conversion, optical power on the scale of hundreds of nanowatts or more can be produced in a miniature form factor across the lifetime of the radionuclide, significantly extending the applicability of the previously-abandoned “nuclear” power approach for implant energy [34]. Finally, conceptual models for system-level packaging and photovoltaic conversion and harvesting efficiency are developed, with a design methodology for an integrated power harvester and sensor hub outlined for future exploration.

Advisor: Ali Niknejad and Mekhail Anwar

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BibTeX citation:

@mastersthesis{Kandala:EECS-2025-17,
    Author = {Kandala, Averal},
    Title = {Harnessing Alpha Radiation to Power Miniaturized Implantable Medical Devices},
    School = {EECS Department, University of California, Berkeley},
    Year = {2025},
    Month = {May},
    URL = {http://www2.eecs.berkeley.edu/Pubs/TechRpts/2025/EECS-2025-17.html},
    Number = {UCB/EECS-2025-17},
    Abstract = {Implantable medical devices (IMDs) have the potential to revolutionize medical diagnostics and therapy, as they provide an avenue for care providers to receive automatic feedback on the state of the patient’s body on timescales greatly accelerated from the appointment-based paradigm of today. However, three main challenges present themselves when we consider how best to integrate IMDs with the patient’s physiology without compromising on quality of life: scalability, longevity, and convenience.

The critical factor limiting progress on all three of these frontiers is power. Although research on novel battery technologies is ongoing, commercially-available batteries simply cannot provide sufficiently long-lasting power at the scales required for most chronic diagnostic sensing applications [9, 12], and alternative “independent” power strategies either carry short lifetimes or cannot be miniaturized [41]. In the absence of a proven miniaturized independent power source, research in the last decade has focused on the development of discontinuous powering models that rely on an external device, called the “interrogator”, to beam in power for harvesting by a receiver on the implant and establish a channel for communication with the implant [7, 38, 43, 44]. Ultrasound has emerged as the most promising such model due to its low attenuation in tissue and high time-averaged intensity limit as outlined by the FDA [7, 43, 44].

However convenient this type of model might be for enabling design miniaturization, it fails in general to deliver system-level convenience from the perspective of the patient, as the interrogator typically must be optimally aligned with the implant to ensure correct operation [31]. In addition, the implant simply cannot operate when it is not receiving power from the interrogator, limiting the diagnostic applicability of these models. 

In order to develop the miniaturized independent power source that would overcome these challenges, this work presents a strategy for converting the energy of alpha radionuclides into light for harvesting by a physically surrounding photovoltaic structure. By using phosphorescent materials to achieve this conversion, optical power on the scale of hundreds of nanowatts or more can be produced in a miniature form factor across the lifetime of the radionuclide, significantly extending the applicability of the previously-abandoned “nuclear” power approach for implant energy [34]. Finally, conceptual models for system-level packaging and photovoltaic conversion and harvesting efficiency are developed, with a design methodology for an integrated power harvester and sensor hub outlined for future exploration.}
}

EndNote citation:

%0 Thesis
%A Kandala, Averal
%T Harnessing Alpha Radiation to Power Miniaturized Implantable Medical Devices
%I EECS Department, University of California, Berkeley
%D 2025
%8 May 1
%@ UCB/EECS-2025-17
%U http://www2.eecs.berkeley.edu/Pubs/TechRpts/2025/EECS-2025-17.html
%F Kandala:EECS-2025-17