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Takeuchi discusses evolution
of battery technology for ICDs
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“Today’s students coming through freshman chemistry at UB, they’re learning about the ICD battery that was developed here in Western New York. That’s pretty cool stuff.”
This season’s UBThisSummer lecture series concluded Wednesday with a special treat: a talk by renowned inventor Esther Takeuchi on the evolution of battery technology for implantable medical devices.
Takeuchi, a SUNY Distinguished Professor in the School of Engineering and Applied Sciences, began her talk on medical batteries by showing the audience of about 100 people an old, black-and-white photograph of a man pushing a bulky, external pacemaker on a cart.
“What is the size of their world?” Takeuchi asked, before answering her own question: “The size of their world is determined by the length of the extension cord.”
Today, pacemakers—which monitor patients’ heart rates and emit an electrical signal reminding the heart to beat when rates are low—are one of many implantable medical technologies that translate into freedom for patients. Others include ventricular assist devices, which pump blood in place of the heart; programmable pumps that release drugs at appropriate time intervals; and neurostimulators that hold promise for treating a wide variety of disorders, including chronic pain, epilepsy and even psychiatric disorders.
Takeuchi, recipient of the 2008 National Medal of Technology and Innovation, the nation’s highest award for technological achievement, played a critical role in bringing implantable medical products to market. While working for Greatbatch Inc., her previous employer, she developed the lithium/silver vanadium oxide battery technology that most implantable cardiac defibrillators (ICDs) still employ.
The current—the flow of energy—in a battery consists of electrons moving from a starting point called an anode to a terminus called a cathode. Often times, batteries are the technology that determines whether a specific medical device is possible to create. Since implantable devices must be small, the batteries that power them must be able to store a lot of energy in a limited space.
Creating an energy-storage cell to power an ICD was a particular challenge. The battery would need to last at least five years and defibrillators—which detect irregular heartbeats and correct them with a jolt of energy—would need to support a pulsatile current about 1 million times as strong as the current pacemakers needed.
The design that Takeuchi and her colleagues developed increased the strength of the current by increasing the surface area of active material by stacking alternating layers of anodes and cathodes alongside one another. The cathode material employs two types of metal (silver and vanadium) in the molecules instead of one, containing more energy in a fixed volume and providing state-of-charge indication, which enables the physician to determine when to replace the device.
The ICD is a life-saving technology, with more than 300,000 patients receiving the implants every year. Takeuchi joked that “I really knew that I made it” when she saw her lithium/silver vanadium oxide battery in a freshman chemistry textbook.
“Today’s students coming through freshman chemistry at UB, they’re learning about the ICD battery that was developed here in Western New York,” Takeuchi said. “That’s pretty cool stuff.”
And today, Takeuchi and her students are researching new cathode materials for energy-storage devices. Phosphates embedded with silver ions that generate silver nanowires inside the cathode have shown particular promise. They would be a winning combination because phosphates are stable under extremely high temperatures, and silver is highly conductive.
Takeuchi says that in the past two years, the world has turned its attention to batteries like never before. That’s because as countries invest in alternative energy, they will need long-lasting, high-energy batteries to power electric vehicles and store the energy that solar arrays and wind farms produce. The expertise of researchers like Takeuchi who have worked in health care will be critical to developing this next generation of energy-storage technology.
Decades ago, the hard work and imagination of Takeuchi and her colleagues enabled the widespread application of ICDs, which have changed the lives of millions of Americans. Now, battery scientists are again at the forefront of a great revolution.
As Takeuchi concluded her talk, ending this year’s UBThisSummer lecture series, her listeners, old and young, thanked her with a long round of applause.
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