Energy harvesting system for wireless body sensor nodes

In this paper a photovoltaic energy harvesting system for wireless body area network applications is presented. The device is able to store the energy produced by the harvester in a storage element, acquire data from a generic body sensor and transmit the information wirelessly to an external receiver. The system is supplied by a thin-film photovoltaic energy harvester, which is capable of ensuring a proper functioning of the system even in indoor lighting conditions, when the incident power is limited. The energy is accumulated in a supercapacitor, and, once enough energy has been stored, the data from the sensor are collected and transmitted to the receiver. The interface exhibits negligible power consumption during the charge of the capacitor. Wireless transmissions can be performed through a Bluetooth^® or Zigbee^® module to a smartphone or a personal computer, which is used as main receiver. The harvesting system proposed in this paper is fully autonomous, since no battery is required even for the start-up, and is designed to be coupled to a variety of sensors which can be worn by the patient.