Design of a DC-DC Boost Converter of Hybrid Energy Harvester for Low-Power Biomedical Applications

Abstract

The growing need for alternative sources for powering Sensors and wearable devices has led to many energy harvesting solutions by which we can consequently replace batteries. The typically small amount of energy provided needs to be efficiently managed to be able to supply biomedical applications. In biomedical sector, continuous power requirement is crucial. Available human energies can be utilized for this purpose. But as only small and limited energies can be extracted from human body, the main challenge is to enhance this low energy output with the design of proper electronic circuits to capture and increase the energy output. In a lot of cases one harvester is not sufficient. As a solution for this issue we found combinations of converters in hybrid structures an efficient technique for boosting the amount of converted energy. However, energy converters need to be designed in a proper manner fitting to the properties of ambient sources. This work reports about the design of a boost converter for an hybrid energy harvesting solution using three ambient sources, which are Radio Frequency, thermal energy and vibration for powering low power biomedical applications. In this work the use of power extracted from human body is investigated for both thermal and vibration source. The proposed boost converter is used to boost the limited input voltage from thermal, radio frequency, and vibration. The inductance in the circuit is varied from 0.3 to 1.4 μH for thermal source and from 0.10 to 0.21μH for the hybrid inputs in order to achieve the desired output range. For the hybrid structure the optimum inductance value is set to 0.21 μH to achieve the required output voltage of 3.0 to 5.5V. The converter consumes 0.28 mW of power, delivers 3.3 mW of output power, and is 91.6 % efficient for a 500 mV input. All circuits are designed and simulated using LTSPICE software.