Nanosized Implantable Sensor to Advance Treatment for Spinal Cord Neurological Disorders and Injury

Implantable technologies have significantly advanced our understanding and ability to modify brain neuron activity; however, studying neurons within the spinal cord during active movement has been more challenging. This difficulty arises because the spinal cord is highly mobile, shifting position whenever a person turns their head or bends over, as a result of which the spinal neurons are also moving. During such movements, rigid sensors implanted in the spinal cord can disturb or even damage the fragile tissue. Gaining a deeper understanding of how spinal neurons process sensations and control movement is crucial for developing more effective treatments for spinal cord diseases and injuries. Now, researchers have developed a tiny sensor called spinalNET which records the electrical activity of spinal neurons without interfering with normal activity. This capability marks a significant initial step toward creating potential treatments for millions affected by spinal cord diseases.

In their research, neuroengineers at Rice University (Houston, TX, USA) utilized spinalNET to observe neuronal activity within the spinal cord of freely moving mice over extended periods and with high resolution, successfully monitoring the same neurons for several days. Notably, spinalNET is more than a hundred times thinner than a human hair, making it exceptionally soft and flexible—comparable in softness to the neural tissue itself. This softness provides the necessary stability and biocompatibility to safely monitor spinal neurons as the spinal cord moves. With spinalNET, researchers can capture clear, low-noise signals from hundreds of neurons.

Image: The sensor can record the activity of spinal cord neurons in a freely moving animal model (Photo courtesy of Jeff Fitlow/Rice University)

The spinal cord is integral to movement control and other essential functions. The ability to record spinal neuron activity with precise spatial and temporal resolution during natural motion opens up new possibilities for understanding the underlying mechanisms. Through the use of spinalNET, researchers discovered that neurons in the central pattern generator—a neural circuit capable of producing rhythmic motor patterns like walking without specific timing cues—are involved in functions beyond mere rhythmic movement. Looking ahead, the researchers aim to delve deeper into the complexities of spinal neuron function, exploring how these neurons differentiate between reflexive motions—such as reactions to sudden stimuli—and voluntary actions.

“Up until now, the spinal cord has been more or less a black box,” said Lan Luan, an associate professor of electrical and computer engineering and a corresponding author on the study. “In addition to scientific insight, we believe that as the technology evolves, it has great potential as a medical device for people with spinal cord neurological disorders and injury.”

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