Design of Self-Powered WMD using Multi-Source Energy Harvesting Technique.

Abstract

People can prevent illness and maintain their health in daily life through Wearable Medical Devices (WMDs), which continuously track health conditions. Low reliability, high battery consumption, and huge dimensions are just a few of the problems with wearables. One key challenge is to provide a reliable power supply. This paper presents a Multi-Source Energy Harvesting Technique to extend the lifetime of batteries in   WMDs that combines four different ambient energy sources such as light, Radio Frequency (RF), vibrations, and temperature differences. It contains two main parts, namely energy conversion circuitry and Power Management Unit (PMU). In the first part of our proposed design, the solar energy conversion circuitry boosts the 0.7 V input voltage to 1.6 V at the output. The RF energy conversion circuitry converts 200 mV (2.45 GHz) AC source into 800 mV. A very low input of 200 mV is converted to 1 V by the thermal energy conversion circuitry. The input from a piezoelectric source which is 700 mV, 200 Hz AC signal is converted to 1 V DC signal at the piezoelectric energy conversion circuitry. In the PMU, the outputs from individual harvesters are combined into a 5 V DC which is then regulated into a 3.3 V. Finally, the regulated voltage is divided into three output voltages 1.8 V, 1 V, and 0.5 V as required by WMD sub components such as signal-processing unit, AFE unit, and sensor unit. The proposed technique is implemented schematically in 90-nm CMOS technology using the Cadence Virtuoso design tool and analyzes several parameters such as transistor count, power consumption, start-up time, and efficiency. From the results, it is evident that our proposed design provides better results in terms of lesser propagation delays, fewer transistor counts, and high voltage conversion ratios.