One of the great "meta" areas of investigation for the scientific community is how to attain greater efficiency in sustainable energy creation and storage, from solar power arrays to car batteries to batteries for mobile phones and laptops.
To the quest for greater sustainability in these industries one can add cardiac pacemakers, and one pioneer of the technology says it could be ready for trials sooner rather than later.
"It's not far," M. Amin Karami, PhD, director of the Intelligent Dynamic Energy and Sensing Systems Lab at the State University of New York at Buffalo, said. "We can have the technology ready for animal tests and maybe even for human trials, in two years."
Karami supervised work by UB doctoral student Hooman Ansari, in which Ansari and colleagues recently created a piezoelectric energy harvester that converts the heart’s vibrational energy into electricity. The work, which was published in Smart Materials and Structures and the Journal of Intelligent Material Systems and Structures, is but one of several recently published experiments that illustrate the overall quest for sustainable systems has reached critical mass in cardiac device research. In fact, Karami came to the field through his earlier work on larger-scale energy harvesting systems, in aviation and bridge safety in particular.
In addition to the UB work, other recent advances include:
- A project led by University of Connecticut researcher Islam Mosa. Mosa was exploring the suitability of a tiny device composed of graphene and the protein myoglobin as a biosensor, and serendipitously discovered it could serve as a biocompatible supercapacitor, or energy storage device, that uses serum as electrolyte. The device Mosa fabricated has three to 11 times the density of commercially available thin film electrochemical capacitors, without fear of toxicity. The supercapacitor is only one micron wide—about 1/10 the width of a human hair.
- A leadless pacemaker designed by researchers at Rice University and the Texas Heart Institute, which harvests energy from radio frequency radiation transmitted from an external power source. In a prototype device presented at the IEEE International Microwave Symposium in June, the wireless power transmitter can be up to few centimeters away, according to information provided by Rice. The chip at the system’s heart receives power using microwaves, and the frequency of the pacing signals produced by the pacemaker can be adjusted by increasing or decreasing power transmitted to the receiving antenna.
The pursuit of longer-lived energy systems in pacemakers is especially important for patients, as procedures to replace the devices introduce risks for complications that more efficient—or, ideally, indefinitely sustainable devices—would not. In fact, British cardiologists John Dean and Neil Sulke, in a 2016 article in BMJ, called the current practices of replacing batteries in cardiac pacemakers and implantable defibrillators a "scandal," suggesting that with existing technology, engineers could design and build pacemakers that would last for 25 years or more.
How the researchers' new technologies may be integrated in the next steps of investigation presents intriguing possibilities. For instance, Mosa said the next step of his team's research will be to create an energy harvester that will work in tandem with the supercapacitor. He is considering several possibilities, including a thermoelectric device that would convert body heat to energy, and two piezoelectric approaches: one that would provide power to the storage device from a harvester implanted near a moving joint, and the other a heart-located approach similar to Ansari and Karami's version. Such a coupled device, Mosa thinks, would still be only about 1 centimeter square and only 11-15 microns thick, or slightly thicker than hair. He says it's an exciting time to be pursuing this type of research, and sees others' work as complementary more than competition.
"No, I don't think of it as competition," he said. "It's more like we need each other to complete this."
And, Karami said, he is already hearing interest among cardiac patients for devices like this.
"In the past, people have contacted us—I'm serious—and said, 'I want to go for my next pacemaker—should I wait?'" he said with a laugh. "Obviously, no. It wont happen earlier than five years at least, to be absolutely optimistic. But technologywise, we're not far."