Thermal energy harvesting from human warmth for wireless body area network in medical healthcare system

In the medical healthcare system, wireless body area network (WBAN) is used to monitor the fall event of a patient by sensing his/her body state orientation (stand or fall posture). However, for a conventional WBAN, the only way to communicate with the doctors´ computers or hospital´s servers is through the local gateway. Hence, the reliability of the WBAN is greatly dependent on the life span of the gateway. In this paper, a selective gateway method based on the residual energy of the sensor nodes has been proposed. By changing the gateway, the lifetime of the WBAN can be extended. To further increase the lifetime of the WBAN, a thermal energy harvesting system has been proposed to harvest heat energy from human warmth. Energy harvested using the thermoelectric generator (TEG) is stored in an energy storage device until sufficient energy is available. Based on the experimental test results obtained, the accumulated energy is around 1.369 mJ to power the loads comprising of sensor, RF transmitter and its associated electronic circuits. The sensed information is transmitted in 5 digital words of 12-bit data across a transmission period of 120 msec. The receiver platform displays the patient identification number and sounds out an alarm buzzer for aid if a fall event is detected.