Gallium oxide and radiation will create a power source that is not afraid of time.
A standard battery is ill-suited for equipment that's virtually impossible to access. On the ocean floor, in space, or at a remote unmanned station, a power source must operate for months, or better yet, years, without recharging or replacement. It's precisely for these conditions that radiovoltaic cells —devices that generate electricity directly from radioactive decay—are being promoted.
The new project is supported by DARPA, the US Defense Advanced Research Projects Agency. A team from the University of Toledo is participating in the work as part of a consortium led by the University of Missouri. The program has been awarded $2.8 million. The researchers will create microscale radiovoltaic systems for buoys, spacecraft, and remote sensors, where conventional batteries quickly reach their limits.
The principle of radiovoltaics is similar to solar panels, but instead of light, it uses radiation from radioactive material. A solar cell converts photons, or particles of light, into electricity. A radiovoltaic device works with other particles produced by radioactive decay. This system allows energy to be generated in areas where sunlight is either unavailable or too unstable. For deep-sea equipment and long-duration space missions, the difference is crucial: the system requires a constant power source, independent of day or night, cloud cover, or distance from the sun.
The researchers aim to achieve a power density of 10 watts per kilogram. This indicator reflects how much energy a system produces for a given weight. This parameter is especially important for compact, autonomous equipment: the more watts extracted from each kilogram, the easier it is to meet strict volume constraints and the less the payload has to be sacrificed.
One of the key materials in the project is gallium oxide. It's a semiconductor, meaning it conducts electricity differently than ordinary metal, making it well-suited for electronics and energy conversion. Gallium oxide was chosen for its radiation resistance. In a radiovoltaic device, the active region is constantly near the radiation source, so the substrate must not only perform its function but also maintain its properties under load. Increased radiation resistance offers two advantages: it helps improve energy conversion efficiency and extends the lifespan of the device.
Some of the work at the University of Toledo involves computer modeling rather than manufacturing the devices themselves. Researchers calculate various design options in advance, even before moving on to producing prototypes. This is accomplished using the finite element method. The approach is simple: a complex structure is broken down into many small sections and the behavior of electric fields, currents, heat, and other parameters is calculated in each section. This method helps understand which geometry and which set of materials will produce the desired result without wasting time and money on an endless series of physical prototypes.
After successful calculations, teams can hand over specific designs to colleagues involved in manufacturing and testing. From the very beginning, the entire process is structured as an iterative cycle between modeling, assembly, and verification. First, one team proposes a design, then the partners create a real prototype, after which the results are fed back into the calculations to refine the next version. For complex semiconductor systems, this iterative approach has long been the norm: without it, it is difficult to quickly reach operating parameters.
The consortium, in addition to the University of Toledo and the University of Missouri, includes Pennsylvania State University, the University of Houston, and the U.S. Naval Research Laboratory. This team was not assembled for the sake of formality. Radiovoltaics requires multiple competencies: some specialists are responsible for materials, others for modeling, and still others for design and practical engineering.
The project's ultimate goal is quite practical. The developers want to bring radiovoltaic power sources closer to real-world use in areas where traditional batteries are inconvenient or quickly become irrelevant. For a buoy in a remote ocean region, an autonomous sensor , or a spacecraft, the benefits are measured in more than just service life. The less maintenance such equipment requires, the cheaper and more reliable the entire mission becomes.
If the work achieves the required power density and sufficient longevity, radiovoltaics could fill a niche between conventional batteries and larger nuclear power systems. Massive consumer technology is not yet on the table. However, for devices that must operate for years in isolation, without sunlight and without the ability to quickly replace the battery, such a power source could prove far more practical than conventional solutions.
A standard battery is ill-suited for equipment that's virtually impossible to access. On the ocean floor, in space, or at a remote unmanned station, a power source must operate for months, or better yet, years, without recharging or replacement. It's precisely for these conditions that radiovoltaic cells —devices that generate electricity directly from radioactive decay—are being promoted.
The new project is supported by DARPA, the US Defense Advanced Research Projects Agency. A team from the University of Toledo is participating in the work as part of a consortium led by the University of Missouri. The program has been awarded $2.8 million. The researchers will create microscale radiovoltaic systems for buoys, spacecraft, and remote sensors, where conventional batteries quickly reach their limits.
The principle of radiovoltaics is similar to solar panels, but instead of light, it uses radiation from radioactive material. A solar cell converts photons, or particles of light, into electricity. A radiovoltaic device works with other particles produced by radioactive decay. This system allows energy to be generated in areas where sunlight is either unavailable or too unstable. For deep-sea equipment and long-duration space missions, the difference is crucial: the system requires a constant power source, independent of day or night, cloud cover, or distance from the sun.
The researchers aim to achieve a power density of 10 watts per kilogram. This indicator reflects how much energy a system produces for a given weight. This parameter is especially important for compact, autonomous equipment: the more watts extracted from each kilogram, the easier it is to meet strict volume constraints and the less the payload has to be sacrificed.
One of the key materials in the project is gallium oxide. It's a semiconductor, meaning it conducts electricity differently than ordinary metal, making it well-suited for electronics and energy conversion. Gallium oxide was chosen for its radiation resistance. In a radiovoltaic device, the active region is constantly near the radiation source, so the substrate must not only perform its function but also maintain its properties under load. Increased radiation resistance offers two advantages: it helps improve energy conversion efficiency and extends the lifespan of the device.
Some of the work at the University of Toledo involves computer modeling rather than manufacturing the devices themselves. Researchers calculate various design options in advance, even before moving on to producing prototypes. This is accomplished using the finite element method. The approach is simple: a complex structure is broken down into many small sections and the behavior of electric fields, currents, heat, and other parameters is calculated in each section. This method helps understand which geometry and which set of materials will produce the desired result without wasting time and money on an endless series of physical prototypes.
After successful calculations, teams can hand over specific designs to colleagues involved in manufacturing and testing. From the very beginning, the entire process is structured as an iterative cycle between modeling, assembly, and verification. First, one team proposes a design, then the partners create a real prototype, after which the results are fed back into the calculations to refine the next version. For complex semiconductor systems, this iterative approach has long been the norm: without it, it is difficult to quickly reach operating parameters.
The consortium, in addition to the University of Toledo and the University of Missouri, includes Pennsylvania State University, the University of Houston, and the U.S. Naval Research Laboratory. This team was not assembled for the sake of formality. Radiovoltaics requires multiple competencies: some specialists are responsible for materials, others for modeling, and still others for design and practical engineering.
The project's ultimate goal is quite practical. The developers want to bring radiovoltaic power sources closer to real-world use in areas where traditional batteries are inconvenient or quickly become irrelevant. For a buoy in a remote ocean region, an autonomous sensor , or a spacecraft, the benefits are measured in more than just service life. The less maintenance such equipment requires, the cheaper and more reliable the entire mission becomes.
If the work achieves the required power density and sufficient longevity, radiovoltaics could fill a niche between conventional batteries and larger nuclear power systems. Massive consumer technology is not yet on the table. However, for devices that must operate for years in isolation, without sunlight and without the ability to quickly replace the battery, such a power source could prove far more practical than conventional solutions.
