Penn State researchers develop 3D printed bioelectrodes tailored to individual brain geometry

Researchers at Penn State University have developed a method for 3D printing soft brain electrodes shaped to match the unique surface geometry of individual patients, with the goal of improving neural monitoring for neurodegenerative diseases. 

The work was published in Advanced Materials and set out to address a common, persistent limitation in neural interface technology: standard bioelectrodes are made from rigid materials in generic shapes that fail to conform to the brain’s highly variable surface topology.

The brain’s outer surface is folded through a process called gyrification, forming ridges known as gyri and grooves known as sulci. While major cortical folds are consistent across individuals, the precise arrangement varies considerably from person to person and conventional electrode designs do not account for this variation.

“Each person has a different brain structure, depending on their height, weight, age, sex and more,” explained Tao Zhou, Wormley Family Early Career Professor and assistant professor of engineering science and mechanics at Penn State, and corresponding author on the paper. “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.”

Fabrication process and material choices

The team built electrodes primarily from hydrogel, to match the mechanical properties of brain tissue as closely as possible. A honeycomb-inspired geometry was used to balance flexibility with structural strength while keeping production time and material use low.

“The honeycomb structure helps us significantly reduce the stiffness of the electrodes, without sacrificing their mechanical strength,” Zhou stated. “What’s more, the structure helps us reduce the overall material used during fabrication, reducing production time, cost and environmental impact.”

The production process begins with an MRI scan, which feeds into finite element analysis to generate a detailed simulation of the patient’s neural structure. Software then shapes a customized electrode model, which is printed using direct ink printing — a technique capable of producing electrodes that can monitor and transmit brain signals across a relatively small surface area.

The team 3D printed brain models based on MRI data from 21 patients and physically measured how well the electrodes conformed to each surface. The hydrogel electrodes demonstrated near-perfect electrical connectivity and, unlike stiffer alternatives, could be applied without damaging soft brain tissue. In 28-day rat model trials, the electrodes produced no immune response and maintained consistent performance throughout.

“Personalizing the electrodes to the brain’s specific structure substantially improves their reliability,” Zhou said. “Because they conform to the brain better, the signal quality itself is significantly improved.”

The research team now plans to extend the work toward clinical applications. “We are looking to further improve this technology to optimize the electrodes to monitor for specific diseases,” Zhou said. “In the future, we would really like to work with patients to see how this approach could support brain monitoring and disease treatment in clinical settings.”