Leti, a CEA Tech Institute, and STMicroelectronics have developed a system that can harvest the energy from sporadic impacts. Unlike previous systems, which harvest energy from regular vibrations, this new system can harvest energy from sporadic impacts like a car driving over a speed bump or braking suddenly.

Leti's contribution to the advance is a system capable of switching from standby to on (to save energy) when an impact is detected. Once the system is on, it converts the energy generated by the impact into electrical energy using a non-linear method called synchronous electric charge extraction. The resulting energy-harvesting system measures around a centimeter and contains a piezoelectric resonator that is deformed during an impact and a smart integrated circuit that manages the harvesting of the electric charge when the piezoelectric material reaches its maximum deformation to ensure optimal electromechanical transfer. Compared to previous systems, this new system can harvest four times more energy in similar excitation conditions and delivers positive yields if the average harvestable power is more than around ten nanowatts.

The system was tested on a miniature vehicle mounted on a vibrating container to simulate realistic impacts and was used to power a sensor node that measures acceleration and temperature as well as data transmission.