Self-powered co-harvesting for batteryless sensing and monitoring in two-wheeled IoT applications

The growing adoption of Internet of Things (IoT) devices in mobility applications such as biking can surely improve safety and performance, but it also increases reliance on small, on-board batteries. Energy-autonomous platforms that harvest energy from the environment without introducing friction can reduce the need for batteries on-board. This work presents a hybrid energy harvesting architecture integrating thermoelectric generators (TEGs) on brake pads and small photovoltaic (PV) cells. These two sources are often complementary in mountain biking and can supply light, friction-free harvesting in under highly variable conditions in terms of braking events and ambient illumination. We provide a characterization of both energy input and system-level power consumption to assess energy neutrality in two possible use cases: in the first case, we consider a standard telemetry application (brake temperature and suspension elongation sampling), while in the second case we consider on-board electronics such as wireless shifters, dropper posts and power meters. Results show energy neutrality is achievable in both cases, confirming the interest in implementing friction-free harvesting in bikes. The telemetry application can operate continuously in downhill sections, using TEG power alone, while PV power under bright daylight conditions enables periodic sensing every 0.77 seconds. We also confirm that the harvested energy can sustain wireless remotes and sensors such as power meters. Other actuators such as gear shifters, active suspension systems, or dropper posts still consume 10 to 100 times more than what the harvesting system can output (measured maximum is 3.2 mW), but system optimization on both power production and consumption can close the gap, further expanding the potential of friction-free harvesting in mobility applications.