Evaluation of a vibration-powered, wireless temperature sensor for health monitoring

RLW, Inc designed and built a prototype vibration-powered, wireless temperature sensor for condition based maintenance (CBM) applications. To reduce installation and maintenance costs, the CBM industry is turning increasingly toward wireless sensors, but a major impediment to more widespread implementation of wireless sensors for CBM is that many are powered by batteries that must be regularly replaced. The sensor described in this paper eliminates that problem because power to operate the sensor is generated from ambient vibrations of the device to which the sensor is mounted. This paper describes the design approach and preliminary laboratory test results of the prototype sensor. The sensor will run indefinitely, reporting its temperature once per minute if vibration levels of the machine to which it is mounted are 0.2 g RMS or greater (at the generator´s resonant frequency - 88, 96, 101, 108 Hz described in this testing). When the platform vibration stopped the sensor for an additional 60 to 120 minutes (with reporting rages ranging from every minute to once an hour) before turning itself off until vibration input is restored