Battery-less Wireless Sensors


Battery-less Wireless Traffic Sensor

This research develops a novel battery-less wireless sensor that can be embedded in the road and used to measure traffic flow rate, speed and vehicle weight. Compared to existing inductive loop based traffic sensors, the new sensor is expected to provide increased reliability, easy installation and low maintenance costs. The sensor uses power only for wireless transmission and has ZERO idle power loss. Hence the sensor is expected to be extremely energy efficient. Energy to power this sensor is harvested from the short duration vibrations that results when an automobile passes over the sensor. Since all of the earlier work in literature on vibration energy harvesting has focused on continuous sources of vibration, this paper focuses on short duration vibrations and on developing low power control algorithms that can be implemented on the sensor using an analog circuit. To this effect this research has developed and compared three control algorithms “Fixed threshold switching”, “Maximum Voltage switching” and “Switched Inductor” for maximizing this harvested energy. The “Switched inductor” algorithm is shown to be the most effective at maximizing harvested energy. Experimental results are presented in the final section of the paper and show that adequate energy can be harvested from the passing of each axle of a vehicle to enable successful wireless transmission of data.

Battery-less Wireless sensor in Knee Implants

The algorithms and sensor design developed for the traffic sensor can be extened to many other applications. We are working on implementing such a sensor in an Artificial Knee Implant. This sensor would harvest energy during gait, and monitor the health of the implant. More details will be available, upon completion of the project.

Current Results

The algorithm has been shown to reliably transmit arrival of automobile.
The Switched Inductor has been shown to be the most efficient algorithm

Photograph of novel Battery-less Wireless Traffic Sensor

Sensor Photo

Video of the novel Battery-less Wireless Sensor in action