Penn State researchers have developed soft, 3D-printed electrodes tailored to individual brain folds, reporting closer contact in simulations and tests on printed brain models. The team also reported improved brain-signal recording in rats.
The approach combines MRI-based anatomical mapping, computer modeling and custom fabrication. The reported experiments involved reconstructed human brain surfaces and animal tests, rather than implants in people.
The devices are designed for electrocorticography, or ECoG, which records electrical activity from the brain’s surface. Differences in the cortex’s ridges and grooves can make it difficult for a standard electrode design to maintain contact. Poor contact can produce weaker or noisier electrical signals.
Designing electrodes around brain anatomy
The researchers reconstructed three-dimensional brain surfaces using MRI data from 21 people in the Open Access Series of Imaging Studies database. They analyzed differences in cortical folding and used surface-curvature analysis and selected brain regions to guide personalized electrode designs.
The resulting device, called the honeycomb-inspired printable gel electrode, or HiPGE, combines soft hydrogel-based materials with an open hexagonal lattice. The researchers fabricated electrodes using direct ink writing.
Corresponding author Tao Zhou said the honeycomb structure reduced electrode stiffness without sacrificing mechanical strength. The design is intended to help the electrodes conform to uneven brain surfaces while remaining strong enough to handle.
In simulations and tests using printed brain models, the researchers reported that the personalized electrodes followed cortical contours more closely than comparison designs. These findings concern modeled surfaces, rather than measurements from human implants.
Rat tests and limits of the findings
The team also tested personalized electrodes on rat brains and compared their recordings with those from conventional electrodes. The researchers reported better recording performance with the personalized devices.
Zhou said rats implanted with the printed electrodes for 28 days did not exhibit an immune response. The team also reported no degradation in electrode performance during that period. These are the researchers’ reported findings from animal experiments.
The study authors additionally state that the porous structure allows fluid exchange around the implant. That assertion is separate from the reported improvements in fit and recording performance.
The model and rat experiments do not establish long-term safety or clinical effectiveness in people. Zhou said the team planned to refine the electrodes for monitoring specific diseases and explore their use for brain monitoring and treatment in clinical settings.
