Charging Batteries with Ultrasound

Researchers may have found an easy way to recharge the batteries inside medical implants like pacemakers, reducing or eliminating the need for occasional surgeries to replace them. 

Doctors Leon Radziemski and Inder Makin presented their discovery last weekend at the Acoustical Society of America convention in San Francisco. It comes at a time when more and more people are living with battery-powered implants, which can be used to regulate a variety of conditions. Implants are used to treat people suffering from heart disease, diabetes, and even neurological problems.

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Although they have only released an abstract of their research, the scientists described a technique they've developed to recharge implants in pigs using ultrasound waves. 

In the experiment, ultrasound waves penetrated the pigs' skin and soft tissue to a depth as thick as five centimeters. Although the strength of the current declined based on the thickness of the tissue, the device provided enough energy to charge most medical implants, the researchers said.

“Significant devices such as implants have to be tested in large animals to test for performance reliability and safety,” Radziemski and Makin said in a joint statement to Healthline. “Porcine (pig) tissue for research purposes with ultrasound energy is very similar to human tissue, and we have tested our prototypes in a surgical setting. Still, there is a lot of work ahead before this approach becomes a clinical product.”

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Radziemski is a scientist with Tuscon, Ariz.-based Piezo Energy Technologies. Makin is vice president of devices and radiological health for Medelis and an experienced ultrasound researcher. The National Institutes of Health funded their research.

Batteries with Limited Lifespans

Most medical implants today contain batteries that are not rechargeable, which means patients need surgery to replace them every few years. Radziemski and Makin say traditional batteries last between one and seven years.

Rechargeable batteries have a set lifespan, too, but they only need replacement about every 10 years under normal use, the researchers said.

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With surgery comes the risk of infection and other complications, not to mention significant cost. The healthcare industry is responding with innovative technologies to solve the problem. Some companies have already begun selling charging devices that use electromagnetic induction. 

Radziemski and Makin's device, like others on the market, straps onto the part of the body located over the implant and stays there during charging. Charging could be daily or yearly, depending on the implant's battery life, the researchers said. 

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