Minimally Invasive Nanoelectrodes


Traditional implanted medical devices for brain stimulation are often too hard and bulky for one of the body’s softest and most sensitive tissues.

Lan Luan (from left), Robin Kim, Roy Lycke, and Chong Xie were part of a research team with the Rice Neuroengineering Initiative that developed highly biocompatible and flexible nanoelectrodes that can provide intracortical stimulation with a high degree of spatiotemporal stimulus control. Image Credit: Rice University

To resolve the issue, Paddy University engineers create minimally invasive, ultraflexible nanoelectrodes that can be implanted and used to deliver long-term, high-resolution stimulation therapy.

In rodents, the small implantable device produces a stable, durable, smooth electrode-tissue interface without scarring or degradation, according to research reported in Cell Report. The device delivers electrical pulses that better match the pattern and amplitude of the nerve signaling than standard intracortical electrode stimulation.

Because of the device’s great biocompatibility and good spatiotemporal stimulus control, new brain stimulation therapies, such as neural prostheses for patients with impaired sensory or motor function, can be developed.

This paper uses imaging, behavioral, and histological techniques to demonstrate how these tissue-integrated electrodes enhance stimulation efficacy. Our electrodes send out tiny electric pulses to stimulate nerve activity in a highly controlled way. We can reduce the current required to elicit neural activation by more than an order of magnitude. The pulses can be as subtle as a few hundred microseconds in duration and one or two microamps in amplitude.

Lan Luan, Corresponding Author of the Study and Assistant Professor, Electrical and Computer Engineering, Rice University

The new electrode design from Rice Neuroengineering Initiative researchers represents a significant improvement over traditional implantable electrodes used to treat conditions such as Parkinson’s disease, epilepsy, and obsessive-compulsive disorder, which can cause negative tissue responses and unintended changes in neural activity.

Conventional electrodes are highly invasive. They recruit thousands or even millions of neurons at once. Each of these neurons should have its own tone and coordination in a certain pattern. But when you electrocute them all at the same time, you’re basically disrupting their functionality. In some cases it may work well for you and have the desired therapeutic effect. But if, for example, you want to encode sensory information, you need much more control over those stimuli.

Chong Xie, Corresponding Author of the Study and Associate Professor, Electrical and Computer Engineering, Rice University

Xie compared standard electrode stimulation to the disruptive effect of “blowing an air horn in everyone’s ear or a loudspeaker blaringin a room full of people.

We used to have these huge speakers, and now everyone has an earpiece,” he says.

The capacity to change signal frequency, duration and intensity could lead to the creation of innovative sensory prosthetic devices.

The activation of the neurons is more spread out if you use a larger current. We were able to reduce the flow and show that we have much more focused activation. This can translate to higher resolution stimulation devices.

Lan Luan, Corresponding Author of the Study and Assistant Professor, Electrical and Computer Engineering, Rice University

Luan and Xie are core players of the Rice Neuroengineering Initiative, and their labs are also partners in the advancement of implantable visual prosthetic devices for blind patients.

Imagine one day being able to implant an array of electrodes to restore impaired sensory function: The more focused and deliberate the activation of the neurons, the more precise the sensations you produceLuan notes.

Previous iterations of the device have been used to record brain activity.

We have had a series of publications showing intimate tissue integration enabled by our electrode’s ultraflexible design actually enhances our ability to record brain activity for a longer duration and with a better signal-to-noise ratio.said Luan, who has been promoted to Associate Professor starting July 1.

The study’s lead authors are electrical and computer engineering postdoctoral associate Roy Lycke and graduate student Robin Kim.

This research was supported by the National Institute of Neurological Disorders and Stroke (R01NS109361, U01 NS115588) and the Rice internal fund.

Journal Reference

Lycke, R., et al. (2023). Low-threshold, high-resolution, chronically stable intracortical microstimulation by ultraflexible electrodes. Cell Report.



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