Warding off failure

Imagine a world where heart valves, knee replacements, bridges, or roads could monitor themselves and send a warning signal before failing. Imagine then, if these advanced pieces of technology could power themselves and operate for years without maintenance.

Shantanu Chakrabartty, a researcher at Michigan State University (MSU), has worked for almost a decade on these safety-critical goals. Using four National Science Foundation (NSF) grants since 2006, the associate professor of electrical and computer engineering in MSU’s College of Engineering has focused on the fundamental science behind self-powered sensors for health and usage monitoring.

“My part is the core science that drives this technology,” Chakrabartty says. “I am interested in the device’s physics and in exploring new ways to sense and compute on the sensor. The technology is currently being piloted in different applications, and every new application allows me to optimize the sensor in different ways.”

Self-powered sensors developed by Chakrabartty and his collaborators may be attached to or embedded inside biomedical implants, bridges, pavements, vehicles, and rotating parts. They can autonomously sense, compute, and store cumulative statistics of strain rates, without the aid of batteries.
 

Tiny sensor networks

With NSF support, Chakrabartty discovered a unique synchrony between the physics of flash memory and the physics of devices that convert mechanical stress into energy.

The innovation, called piezoelectricity-driven hot electron injection (p-IHEI), enables miniaturization of energy-harvesting sensors.

These tiny sensors can then be embedded inside structures such. They can even go inside the human body – for instance, in a knee implant or a heart valve.

A network of micro-sized sensors can self-diagnose any catastrophic failure, according to Chakrabartty. Once fully packaged, he hopes the sensor will become an integral part of any smart structure, whether it is civil, mechanical, or biomechanical.
 

Remote access to foil failure

Remotely retrievable with a smartphone, the sensors can predict the onset of mechanical failure. By alerting users to potential problems, the risk of bodily harm is minimized and maintenance costs are reduced significantly.

“Currently, we’re looking at using a diagnostic ultrasound to retrieve data from the sensors implanted in the body,” Chakrabartty says. “This will be highly cost-effective and will be compatible with instrumentation already used by health care professionals. My goal is now to explore new biomedical applications of these sensors and push its limits of performance.”

One sensor application is smart sports helmets that diagnose concussions.

“At a time when we all carry sensors in our pockets and on our wrists to monitor many of our daily activities, technology that enables the assessment of the health of critical infrastructure, vital organs, or the occurrence of life-threatening events is long overdue and sorely needed,” says Massimo Ruzzene, program director in NSF’s Engineering Directorate. “Dr. Chakrabartty’s innovations in the area of remote, self-powered sensing significantly contributes to this need.”

Chakrabartty won an NSF CAREER Award in 2010 for his research in energy-harvesting sensors and processors. Through his Adaptive Integrated Microsystems (AIM) Laboratory at MSU, he has been working on a revolutionary sensing paradigm to help engineers and doctors monitor the health of mechanical structures.

The self-powered sensor research has spawned two U.S. and international patents with several other patents pending. Marketing of the technology is by the MSU Technologies Office, which has led to the formation of Piezonix, a start-up company based in Michigan.

Michigan State University College of Engineering
www.egr.msu.edu