(Published by The Economist; March 21, 2019)
For those whose hearts occasionally go off rhythm, pacemakers are, quite literally, life savers. By providing a small electrical jolt at the right moment, they can keep a heart working at the appropriate pace. Their main drawback is that they use batteries. Even the best of them eventually run out of energy, and replacing the batteries requires surgery.
Since surgery is generally best avoided, the search has been on for long-lasting power sources. Various options have been explored, including, in the 1970s, plutonium. Nuclear-powered pacemakers have thankfully fallen out of fashion and today, devices with lithium batteries last between 5 and 15 years.
Zhang Hao of the Second Military Medical University, in Shanghai, and Yang Bin of Shanghai Jiao Tong University sought a way of recharging a pacemaker’s battery by scavenging energy from inside the body. As they report in the journal ACS Nano they have used the heart muscle itself to power a tiny generator.
Previous attempts to use cardiac muscle power to run pacemakers relied on piezoelectric materials. These release electrons when deformed, and can be attached to beating hearts so that they are slightly bent with each heartbeat, generating electricity. This has worked, but not well enough: the output has rarely exceeded five microwatts, while most pacemakers require at least ten.
Dr. Zhang and Dr. Yang speculated that they could improve matters by arranging for their piezoelectric composites to be more dramatically deformed. First, they created a small capsule from a sheet of flexible polymer a tenth of a millimeter thick. After compression, this capsule would return to its original shape.
They then attached strips of piezoelectric composite to either side of the capsule, attached electrodes to these strips, and covered the strips with a protective layer of silicone. This layout meant that the strips were slightly bent from the beginning and required only a tiny, brief pressure to generate 15 microwatts.
The question was where to put the capsule, either in or on the heart, in order to get a similar effect. A study of cardiac anatomy suggested the pericardial sac, at the organ’s base, would be ideal. It would squeeze the capsule tightly as the heart contracted and still keep a firm grip on it when the heart was relaxed.
To test this idea, the capsule’s electrodes were attached to a commercial pacemaker that had had its battery removed, and surgically implanted into a 50kg Yorkshire pig. The capsule generated enough power for the pacemaker to function normally. Whether such an arrangement will pass human trials remains to be seen. But if it does, the days of pacemakers that need battery replacements, with all their associated surgery, may be numbered.
What an idea, wouldn’t you agree? Use the heart muscle itself to generate the necessary power to recharge the batteries of a pacemaker, apparently the invention of two China-based lead researchers, Drs. Zhang Hao and Yang Bin. But there was no reference made in the highly respected The Economist to another nearly identical study developing such a device, but ongoing not in China, but here in the US at Dartmouth College.
The lawyer in me immediately thought: billions of dollars at stake if this idea can be commercialized. But whose idea is it? Just think about the patent/copyright infringement issues, simmering between the US and China for years. Especially in this instance. Oh yeah, and again, this idea could be worth a fortune.
So, let’s see what’s happening in Hanover, NH, where there’s a China connection in the form of a researcher at Dartmouth’s engineering school.
As recently as February, a report was published noting that engineers at Dartmouth’s Thayer School of Engineering developed a dime-sized device to convert the heart’s kinetic energy into electricity to power a wide range of implantable devices. As noted in the preceding news item in The Economist, pacemaker and defibrillator batteries must be replaced surgically every five to 10 years.
The Dartmouth team’s work proposes modifying pacemakers to harness the kinetic energy of the lead wire that’s attached to the heart, converting it into electricity to continually charge the batteries.
The added material is a type of thin polymer piezoelectric film called “PVDF” and, when designed with porous structures–either an array of small buckle beams or a flexible cantilever–it can convert even small mechanical motion to electricity. The same modules could also potentially be used as sensors to enable data collection for real-time monitoring of patients, according to a university statement.
“We’re trying to solve the ultimate problem for any implantable biomedical device,” said Dartmouth engineering professor John X.J. Zhang, a lead researcher on the study that his team completed alongside clinicians at the University of Texas in San Antonio. “How do you create an effective energy source so the device will do its job during the entire life span of the patient, without the need for surgery to replace the battery?”
“Of equal importance is that the device not interfere with the body’s function,” added Dartmouth research associate Lin Dong, first author on the paper about the three-year study. “We knew it had to be biocompatible, lightweight, flexible, and low-profile, so it not only fits into the current pacemaker structure but is also scalable for future multi-functionality.”
An article on the study appears in Advanced Materials Technologies.
Major med-tech companies have already expressed interest in the technology, according to Professor Zhang (of whom I have no proof is related to the Dr. Zhang in The Economist piece). The two remaining years of National Institutes of Health funding plus time to finish the pre-clinical process and obtain regulatory approval put a self-charging pacemaker approximately five years out from commercialization.
“We’ve completed the first round of animal studies with great results which will be published soon,” Zhang added. Other key collaborators on the study include Dartmouth engineering professor Zi Chen, an expert on thin structure mechanics, and Marc Feldman, MD, professor and clinical cardiologist at UT Health San Antonio.
Neither news piece references the other’s, which is just too hard for this journalist to swallow. Especially with the proximity of less than a month of their publication. That the two teams of researchers didn’t know what each other were doing simply isn’t credible. But each story was published as though the scientific research reported therein was unique.
Which all goes to prove, I cannot be the only one aware of these two disparate groups of researchers–thousands of miles geographically apart–working on the exact same technology with the exact same progress toward a duplicate, phenomenal scientific breakthrough. Somebody at each publisher had to know what was going on and, for some reason, didn’t report that fact in their particular article, you know, as though theirs was a scoop.
I could very well be missing something here, but I doubt it. Enter, the lawyers.