Soft electrodes designed to fit the unique surface of each person's brain may advance neural interfaces for monitoring and treating neurodegenerative diseases, according to a study led by Penn State researchers and announced on Apr. 17.
This development could be important for patients who require precise brain signal tracking, as traditional bioelectrodes are typically made from stiff materials that do not adapt well to the complex structure of individual brains. The new approach uses 3D printing technology and MRI scans from patients to create custom-fit electrodes that better match the folds and grooves of each brain.
The research team simulated detailed brains based on MRI data from 21 human subjects, then shaped and printed electrodes tailored for these structures. Their findings, published in Advanced Materials, showed that these custom electrodes offered improved fit compared to standard designs while maintaining effectiveness and compatibility in tests with rats. "Each person has a different brain structure, depending on their height, weight, age, sex and more," said Tao Zhou, Wormley Family Early Career Professor at Penn State. "Despite this, we try to fit neural interfaces onto brains like they have identical structures. This motivated us to create electrodes that are tailored for each individual, based on the structure of their brain."
The new electrodes are made mainly from hydrogel—a water-rich material—to closely match soft tissue properties and patient-specific geometry. The design features a honeycomb-inspired structure that provides flexibility without sacrificing strength or increasing production costs or time. "The honeycomb structure helps us significantly reduce the stiffness of the electrodes, without sacrificing their mechanical strength," Zhou said.
Production begins with an MRI scan followed by computer modeling using finite element analysis to simulate a patient's neural structure. The hydrogel electrode is then printed using direct ink printing technology for high accuracy over small surfaces.
Tests showed these custom-fitted hydrogel-based electrodes achieved nearly perfect connectivity with electrical signals in the brain while minimizing tissue damage due to their softness compared with conventional stiff materials. When tested on rats over 28 days, there was no immune response or performance loss observed.
Zhou said he believes this method could support commercial-scale manufacturing of patient-specific bioelectrodes: "We are looking to further improve this technology to optimize the electrodes to monitor for specific diseases," he said. He added that future work will focus on clinical applications supporting both monitoring and treatment.
