A 70-to-2 V Triboelectric Energy Harvesting System Utilizing Parallel-SSHI Rectifier and DC-DC Converters

In this article, first integrated circuit (IC) implementation of parallel synchronized switching harvesting on inductor (p-SSHI) is presented for triboelectric energy harvester targeting 1 Hz to 5 Hz mechanical motions. It is accompanied by on-chip buck and switched capacitor DC-DC converters, all capable of handling 70 V levels. Unlike piezoelectric harvesters, triboelectric nanogenerators (TENGs) can produce very high open-circuit voltages; thus, the proposed system utilizes this property within the technology limits to maximize the extracted power. An in-house manufactured TENG using steel and polytetrafluoroethylene (PTFE) is modeled for sub-5 Hz motions. The energy is extracted and stored in an external capacitance until its voltage reaches 70 V, which is achieved in three press-and-release mechanical cycles. 70-to-2 V down conversion is carried on by 70-to-10 V buck converter followed by a 10-to-2 V switched capacitor DC-DC converter. A chip is manufactured in <inline-formula> <tex-math notation="LaTeX">$0.18~\mu \text{m}$ </tex-math></inline-formula> HV BCD process with an active area of 6.25 mm². End-to-end peak efficiency is measured as 32.71% for 1 Hz motion with a 722 <inline-formula> <tex-math notation="LaTeX">$\mu \text{W}$ </tex-math></inline-formula> total power delivery to the load for 4 ms.