Researchers at the University of Waterloo have created a self-powered sensor that could enable remote monitoring of the recovery of surgical patients by doctors.
The small, tube-like device is developed such that it can be fitted to braces following joint surgery to carry out wireless transfer of information to smartphones, computers, or smartwatches to track range of motion and other indicators of improvement.
“That data would be continuously collected, so it would be as though the physician or physiotherapist was always there, always observing the patient,” stated Hassan Askari, an engineering doctoral candidate at Waterloo.
It would also be possible to use the same sensor in different ways, such as in the tires of autonomous vehicles to detect and respond to icy roads.
The researchers have developed and tested a prototype that integrates electromagnetism with triboelectricity, a comparatively new energy harvesting method in which different materials are brought together to generate current.
Upon being twisted or bent, the device produces sufficient electricity for sensing and powering electronic circuits for processing and wireless signal transmission.
“The aim was to develop a sensor that works without having a battery attached to it,” stated Askari. “It is its own power source.”
This renders the device ideally suited for applications that demand high reliability and where it would be challenging or costly to replace worn-out batteries.
Askari predicted that each of the sensors, which have a width of 1 cm and a length of 6 cm, can be commercially manufactured for $5–$10.
At present, the focus is on reducing their size and making them more sensitive with the help of triboelectricity alone. Software is also being created to process signals for the tire application.
Upon being fitted to the inner side of tires, they have the ability to sense varying road conditions and immediately send information to control systems to allow self-driving vehicles to make adjustments.
“Based on the forces, the interaction between the road and the tires, we could actually detect ice or rain,” stated Askari. “That is extremely important information for autonomous driving.”
At Waterloo, Askari partnered with fellow PhD student Ehsan Asadi, and engineering professors Amir Khajepour and Mir Behrad Khamesee, and also doctoral student Zia Saadatnia and professor Jean Zu at the University of Toronto.
A study describing their research appears in the Sensors and Actuators A: Physical journal.