Researchers at the University of Arkansas and the University of Michigan have developed ultra-low-power temperature sensors that operate on graphene-silicon solar cells, eliminating the need for batteries or power-management chips. The result is a compact proof-of-concept for autonomous sensors powered entirely by ambient energy.
Today, most temperature sensors rely on batteries or wired power. Batteries add bulk, have limited lifetimes, and are expensive and inconvenient to replace in remote or hard-to-access locations. In dense sensor networks, even occasional maintenance quickly becomes impractical.
Graphene is an interesting alternative due to its exceptional electrical conductivity, optical transparency, mechanical strength, and flexibility. These properties make it suitable for miniaturized solar cells and, more broadly, for devices that can harvest energy from multiple environmental sources.
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Inside the Graphene-Silicon Microgenerator
The research team constructed dozens of mini graphene-silicon solar cells, wire-bonded them into standard packages, and measured their current-voltage (I-V) characteristics under light. They then connected cells in series to raise the output voltage to levels required by an ultra-low power temperature sensor.
To store the harvested energy, the researchers used three storage capacitors, each charged by a different set of series-connected solar cells.
Instead of routing power through a conventional power-management unit and rechargeable battery, the solar cells charge the capacitors directly. This simplifies the design, reduces overhead power losses, and closely matches the sensor’s nanowatt-level power demand to the available harvested energy.
What is Revealed in the Results
Under light, the graphene-silicon solar-cell arrays charged the storage capacitors in only a few minutes. Once charged, the capacitors powered the temperature sensor system for more than 24 hours without recharging, supporting both active and standby operation.
In doing so, the researchers demonstrated that three sets of series-connected solar cells can meet the voltage requirements of a commercial ultra-low-power temperature sensor.
They also confirmed that ambient solar energy, captured by compact graphene–silicon microgenerators and stored in capacitors, can reliably power a standalone sensing node without the need for batteries or a typical power-management chip.
Toward Multi-Modal Sensors
The solar-powered temperature sensor may be a first step toward multi-modal graphene-based energy harvesters. Previous work from the group suggests that graphene can harness energy from six environmental power sources: solar, thermal, acoustic, kinetic, nonlinear, and ambient radiation.
The next planned device targets kinetic energy by exploiting graphene’s vibrational properties, with the intention of combining this new harvester with the existing solar system.
Over time, the researchers aim to integrate multiple graphene-based microgenerators into compact sensor packages. By drawing on more than one ambient source, such systems could maintain operation even when sunlight is intermittent, such as at night, indoors, or during cloudy weather.
Solar Sensors in the Future
By removing both batteries and power-management chips, the demonstrated system supports a true “set it and forget it” sensing model. Once deployed, these devices could operate for years with minimal intervention, which is especially valuable in remote, hazardous, or widely distributed environments.
Potential applications include agricultural climate monitoring, livestock tracking, infrastructure and environmental surveillance, building systems, and other Internet of Things (IoT) deployments where frequent battery replacement is impractical.
If extended to additional energy sources as the researchers plan, graphene-based microgenerators could enable dense networks of autonomous, long-lifetime sensors that make continuous monitoring far more feasible.
Reference
Press Release. First Graphene-Based Solar Cells Used to Power Temperature Sensors. Arkansas News. Accessed on 12th November 2025.