Researchers have developed a novel neural implant that can be controlled remotely using a magnetic field, paving the way for advancements in medical implants to help relieve pain and provide therapy for people with spinal injuries or neurological diseases.
The system, called MagNI—which stands for magnetoelectric neural implant—includes magnetoelectric transducers that allow the device’s processor to harvest power from an alternating magnetic field outside the body.
|Rice University researchers have introduced a neural implant that can be programmed and charged remotely with a magnetic field for potential use with patients who have neurological disorders. (Image source: Secure and Intelligent Micro-Systems Lab/Rice University)|
A team in Rice’s Brown School of Engineering developed the device, which researchers said could be used to provide electrical stimulation of neurons in patients with epilepsy or Parkinson’s disease, said Zhanghao Yu, a graduate student who worked on the project.
Theoretically, patients could control the implant device at home using a belt that holds the magnetic transmitter, Yu said. “This is the first demonstration that you can use a magnetic field to power an implant and also to program the implant,” he said in a press statement. “By integrating magnetoelectric transducers with CMOS (complementary metal-oxide semiconductor) technologies, we provide a bioelectronic platform for many applications. CMOS is powerful, efficient and cheap for sensing and signal-processing tasks.”
Design and Testing
Researchers developed a device prototype by placing three components on a flexible polyimide substrate--a 2-by-4-millimeter magnetoelectric film that converts the magnetic field to an electric field, a CMOS chip and a capacitor to temporarily store energy.
To test the long-term reliability of the CMOS chip, they soaked it in a solution. Then they tested it in air and jellylike agar, emulating the environment of tissues in which an actual device would be placed.
Researchers also tested the device to see how it would actually stimulate nerves, using a Hydra aris, a tiny octopus-like creature. They constrained the hydra with the lab’s microfluidic devices, observing fluorescent signals associated with contractions in the creatures that were triggered by contact with the device.
Currently, patients with neurological disorders use methods such as ultrasound, electromagnetic radiation, inductive coupling, and optical technologies for neural stimulation. But these all have individual drawbacks for the patients, said Kaiyuan Yang, an assistant professor of electrical and computer engineering at Rice. “People have been demonstrating neural stimulators on this scale, and even smaller,” he said in a press statement. “The magnetoelectric effect we use has many benefits over mainstream methods for power and data transfer.”
For instance, tissues don’t absorb magnetic fields as they do other type of signaling technologies, which can cause damage. Magnetic fields also do not heat tissues like electromagnetic and optical radiation or inductive coupling, Yang said.
And while ultrasound doesn’t have this issue, ultrasound waves can be absorbed through reflection in hair, skin, bones, or other muscle.
There are also technological benefits to using magnets instead of other technologies to control neurostimulation devices that aren’t related to its effect on the human body, Yang said. MagNI as a technology is “calibration free and robust,” as well as does not “require any internal voltage or timing reference,” he said in the statement.
The researchers will publish an upcoming paper on the work, “An 8.2mm3 Implantable Neurostimulator with Magnetoelectric Power and Data Transfer,” on the IEEE Xplore Digital Library.
Researchers currently are performing in-vivo tests of the device on different models, as well as working to develop two-way communication strategies to facilitate data collection from implants as well as to make the device viable for more applications.
Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.