Rechargeable neurostimulator with H-shaped fractal slots in PCB copper layers

Rechargeable neurostimulators make it possible to research and treat brain disorders for a long period of time. However, metal objects such as device cases and inner copper layers of the printed circuit board (PCB) lower the energy transfer efficiency and can even present safety risks due to the eddy currents in these metals. The use of a fractal pattern slot in the metal to suppress the eddy currents is proposed and a rechargeable neurostimulator with deformed H-shape fractal slots in the PCB inner copper layers is described. The results show that the use of an H-shaped fractal pattern slot is effective over a relatively wide frequency range and the maximum temperature of the neurostimulator is in the range of 34.5-39.5°C, which indicates that the device can be used safely for long-term animal studies and even in the clinical treatment of brain disorders.