Power harvesting through headphone jack of android smartphone for low power medical devices

Today smartphones are readily available with source of power, faster processing capabilities and connectivity. In this paper, we propose design of circuit to harvest power from widely available standard 3.5mm headphone jack of smartphone itself. Headphone jack can generate tones (sine or square) within the frequency range of 20-20KHz. we have also developed GUI of an android application for tone generation which plays sine wave. The audio output channels of smartphones from different manufacturers were characterized in order to determine the range of design parameters. Proposed design provides few milliwatts to power mHealth peripherals and enhances practicality of smartphone as a medical device. It could be the better option for battery dependent devices. Headphone jack interface could be used to develop modular platforms to monitor vital signs such as Pulse rate, SpO2, EKG.