Surgical implant could pave the way for real-time sensing of biochemistry, pH and blood oxygen
By the editors of HospiMedica International
Published on April 01, 2022
A wireless millimeter magnetoelectric implant for endovascular stimulation of peripheral nerves could lead to a wide range of low-risk and highly accurate therapies as well as enable real-time sensing of biochemical, pH and blood oxygen levels to provide diagnostics or support other medical treatments. devices.
Engineers from Rice University (Houston, Texas, USA) have published the first proof-of-concept results from a years-long program to develop tiny wireless devices capable of treating neurological diseases or blocking pain. Nerve stimulators do not require batteries and derive both their power and programming from a low-power magnetic transmitter outside the body. The MagnetoElectric Bio ImplanT – aka ME-BIT – is surgically placed and an electrode is passed through a blood vessel to the targeted nerve for stimulation. Once there, the device can be safely powered and controlled with a near-field transmitter worn close to the body. Researchers successfully tested the technology in animal models and found it could charge and communicate with implants several centimeters under the skin. The implant could replace more invasive units currently treating Parkinson’s disease, epilepsy, chronic pain, hearing loss and paralysis.
Image: A small wireless device can treat neurological conditions or block pain (Photo courtesy of Rice University)
The ability to power implants with magnetoelectric materials eliminates the need for electrical leads through skin and other tissues. Leads like those often used for pacemakers can cause inflammation and sometimes need to be replaced. Battery-powered implants may also require additional surgery to replace the batteries. ME-BIT’s portable charger requires no surgery. The researchers showed that it could even be misaligned by several centimeters while still having enough power and in communication with the implant. The 0.8 square millimeter programmable implant incorporates a strip of magnetoelectric film that converts magnetic energy into electrical energy. An on-board capacitor can store some of this power, and a “system-on-chip” microprocessor translates the magnetic field modulations into data. The components are held together by a 3D printed capsule and further encased in epoxy.
According to the researchers, the magnetic field generated by the transmitter – around 1 milliTesla – is easily tolerated by the tissues. They estimated that the current implant can generate a maximum of four milliwatts of power, enough for many neural stimulation applications. Research suggests that endovascular bioelectronics like ME-BIT could lead to a wide range of low-risk and highly precise therapies. The presence of electrodes in the bloodstream could also allow real-time sensing of biochemical, pH, and oxygen levels in the blood to provide diagnostics or support other medical devices. The team ultimately hopes to use multiple implants and communicate with them simultaneously.
“Because the devices are so small, we can use blood vessels as a highway system to reach targets that are difficult to reach with traditional surgery,” said Jacob Robinson of the Rice Neuroengineering Initiative. “We deliver them using the same catheters that you would use for an endovascular procedure, but we would leave the device outside the vessel and place a guide wire into the bloodstream as a stimulation electrode, which could be held in place. with a stent.”
“One of the good things is that every nerve in our body needs oxygen and nutrients, which means there’s a blood vessel a few hundred microns from every nerve,” Robinson said. “It’s just about tracing the right blood vessels to hit the targets. With a combination of imaging and anatomy we can be pretty sure where we are placing the electrodes. »