Millimeter-scale radioluminescent power for electronic sensors

Area of Science:

• Nuclear Engineering
• Materials Science
• Energy Harvesting

Background:

• Miniature untethered systems require compact energy sources.
• Current energy storage and generation at the millimeter-scale present significant challenges.
• Applications include industrial, environmental, and medical sensors.

Purpose of the Study:

• To develop a method for generating electrical energy at the millimeter-scale.
• To address the energy requirements of untethered miniature sensors.
• To explore the conversion of alpha radiation into usable electrical power.

Main Methods:

• Alpha radiation from Thorium-227 (Th-227) was used.
• Phosphorescent and scintillating materials were tested for radiation-to-light conversion.
• Europium-doped yttrium oxide demonstrated the highest conversion efficiency.
• Optical power generation was measured using a photovoltaic harvester circuit.

Main Results:

• Europium-doped yttrium oxide achieved a conversion efficiency of approximately 2%.
• Over 100 nanowatts (nW) of optical power was generated from millimeter-scale volumes (1 mm³).
• Sustained power generation was observed for over two months.
• A clear sealant was employed for safe miniaturization.

Conclusions:

• A two-step process of alpha radiation to light, then to electrical power, is feasible for mm-scale energy generation.
• This method offers a viable solution for powering miniaturized sensors.
• The technology supports the development of untethered medical and Internet-of-Things (IoT) sensors.