Engineers from Rice University in the US have created a neural implant that can be programmed and charged remotely with a magnetic field.
The technology has the potential to be used in embedded devices like a spinal cord-stimulating unit with a battery-powered transmitter attached to a belt.
The integrated microsystem, called MagNI — from magnetoelectric neural implant — uses magnetoelectric transducers that allow the chip to harvest power from an alternating magnetic field outside the body.
The implant could be used to stimulate neurons in people with conditions such as epilepsy or Parkinson’s disease without heating surrounding tissue the way existing techniques do.
“This is the first demonstration that you can use a magnetic field to power an implant,” said Assistant Professor Kaiyuan Yang.
“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.”
The advantages of MagNI over other simulation methods, such as ultrasound and electromagnetic radiation, include gains in power and data transfer.
Testing the prototype
The prototype developed by Yang and his colleagues consists of just three components sat on a flexible polyimide substrate: a magnetoelectric film that converts the magnetic field to an electric field, a CMOS chip and a capacitor to temporarily store energy.
To test the chip’s long-term reliability, the team soaked it in a solution. They then tested it in air and in the jelly-like substance agar, in order to simulate the environment of tissues in which a real device would be placed.
While the current generation of chips allow energy and information to only flow in one direction, Yang said the team is working on developing two-way communication strategies to facilitate data collection from implants and enable more applications.
A team of biomedical engineers from the University of Sydney is also focusing on implants, developing a plasma technology that could help manufactured devices better interact with surrounding tissue.
To function properly within the body, an implant needs to bond and interact with the surrounding tissues and living cells. If this doesn’t happen, the implant, whether it’s an artificial hip or engineered tissue, may be rejected by the body.
The University of Sydney researchers aimed to solve this problem by more robustly attaching hydrogels — a jelly-like substance that is similar in structure to soft human tissue — to polymeric materials.
“Despite being similar to the natural tissue of the body; in medical science hydrogels are notoriously difficult to work with as they are inherently weak and structurally unstable,” said Dr Akhavan, who led the research alongside Professor Marcela Bilek.
“They do not easily attach to solids, which means they often cannot be used in mechanically demanding applications such as in cartilage and bone tissue engineering.”
Akhavan said there were several ways the technology could be used, including to mimic structures such as bone cartilage, or loaded with a drug to release slowly over time.
“These materials are excellent candidates for applications such as lab-on-a-chip platforms, bioreactors that mimic organs, and biomimetic constructs for tissue repair, as well as antifouling coatings for surfaces submerged in marine environments,” he said.
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