Implants that require a constant source of energy but don’t need wires are an idea whose time has come.
Now, for therapies that require multiple coordinated stimulation implants, their timing has also come.
Rice University engineers who developed implants for electrical stimulation in patients with spinal cord injuries have perfected their technique for powering and programming multisite biostimulators from a single transmitter.
A peer-reviewed paper on the advancement of electrical and computer engineer Kaiyuan Yang and colleagues at Rice’s Brown School of Engineering won the award for best paper at the Custom Integrated Circuits Conference of the IEEE, held virtually the last week of April.
Rice lab experiments have shown that an alternating magnetic field generated and controlled by a battery-powered transmitter outside the body, perhaps on a belt or harness, can provide energy and programming to two or more implants at least 60 millimeters (2.3 inches) apart.
Implants can be programmed with delays measured in microseconds. This could allow them to coordinate the triggering of multiple wireless pacemakers in separate chambers of a patient’s heart, Yang said.
“We show that it is possible to program the implants to stimulate in a coordinated pattern,” he said. “We synchronize each device, like a symphony. It gives us a lot of degrees of freedom for pacing treatments, whether for cardiac stimulation or for a spinal cord.”
The lab tested its tiny implants, each the size and weight of a vitamin, on tissue samples, live hydra vulgaris and rodents. The experiments proved that over at least a short distance, the devices were able to stimulate two separate hydras to contract and activate a fluorescent tag in response to electrical signals, and to trigger a response at controlled amplitudes along the sciatic nerve. of a rodent.
“There is a spinal cord regeneration study that shows that multisite stimulation in a certain pattern will help recovery of the neurological system,” Yang said. “There is clinical research going on, but they all use benchtop equipment. There are no implantable tools that can do that.”
The lab’s devices, called MagNI (for magnetoelectric neural implants) were introduced early last year as possible spinal cord stimulators that didn’t require wires to power and program them. This means that the conductors do not have to penetrate the patient’s skin, a situation that could potentially become infected. The other alternative, as used in many battery-powered implants, is to replace them with surgery every few years.
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