Project 1: Chronic Stability of Ruthenium Oxide Electrodes in Rat Motor Cortex
Motivation
Cortically implanted microelectrode arrays (MEAs) are essential for enabling brain-machine interfaces that restore sensory or motor function and facilitate exploration of complex neural networks. A critical bottleneck in MEA performance is the electrode material, which must balance low impedance, biostability, and biocompatibility. While materials like iridium oxide (SIROF) have shown success in long-term neural recordings, their high cost and scalability limit widespread adoption. Ruthenium oxide (RuOx), a lower-cost alternative, has shown similar electrochemical properties to SIROF in acute settings. However, its long-term stability and recording performance remain underexplored. This project aims to evaluate RuOx as a cost-effective and scalable electrode material by assessing its chronic recording and electrochemical stability in vivo, providing critical data to support its potential for future neural interface applications.
Our Solution
To address the need for cost-effective, stable, and scalable low-impedance coatings for neural recording electrodes, we evaluated sputtered ruthenium oxide (RuOx) as a viable alternative to the more expensive iridium-based coatings like SIROF. By applying 120 nm thick RuOx films to a-SiC microelectrode arrays and implanting them into rat motor cortex, we systematically assessed electrochemical stability (via impedance spectroscopy and cyclic voltammetry) and recording fidelity (via single-unit recordings) over a 6-week subchronic period. Our results demonstrate that RuOx maintains stable impedance, charge storage capacity, and consistent signal quality over time, with recording performance comparable to SIROF. This supports RuOx as a promising, low-cost, and scalable electrode material for chronic neural interfaces.
My Contributions
I contributed to both the experimental and analytical components of the RuOx electrode study and led the design of the research poster titled "Chronic Stability of Ruthenium Oxide Electrodes in Rat Motor Cortex." I assisted in collecting in vivo electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) data from implanted a-SiC MEAs and played a role in preprocessing and interpreting these datasets, focusing on impedance changes at key frequency bands and charge storage capacity across sweep rates. For the neural recording component, I supported spike sorting, unit identification, and quantification of key metrics including peak-to-peak voltage (Vpp), signal-to-noise ratio (SNR), and active electrode yield (AEY) across the 16-week timeline. My analysis helped confirm the electrochemical and recording stability of RuOx films over time. I independently developed the scientific poster, synthesizing experimental methods, data trends, and statistical results into a coherent visual narrative aimed at technical audiences, and presented the findings at UT Dallas’s Undergraduate Research Symposium.
Project Outcomes
Poster: URSA 25 Poster
These publications are based on the broader research project I supported (not listed as an author): Electrochemical stability and neural recording with sputtered ruthenium oxide electrodes subchronically in rat motor cortex
Looking to discuss further? Contact me at research@mkmaharana.com
Project 2: Improved Intracortical Insertion Mechanics via Staggered Microelectrode Shank Design
Motivation
Intracortical microelectrode arrays (MEAs) are critical for high-resolution neural recording and stimulation, especially in brain-machine interface applications. While multi-shank MEAs improve spatial sampling and channel density, they are more mechanically invasive than single-shank devices, often leading to increased cortical dimpling, insertion force, and long-term biological reactivity. This insertion-induced trauma contributes to device failure and signal degradation over time. Existing strategies to reduce insertion damage—such as minimizing shank cross-sectional area—compromise mechanical robustness, raising the risk of shank buckling or breakage during implantation. There is a clear need for MEA designs that reduce mechanical trauma without sacrificing structural stability.
Our Solution
To address this challenge, we collaborated with NeuroNexus to develop a custom four-shank MEA with staggered shank lengths and non-uniform longitudinal thickness. The staggered geometry ensures that each shank enters the cortex sequentially rather than simultaneously, distributing the mechanical load and minimizing cortical deformation during insertion. Thinner distal ends at the recording sites reduce tissue resistance, while thicker proximal regions improve rigidity. Finite element modeling (FEM) confirmed that each shank's critical buckling force exceeded the measured cortical penetration force by a factor of six or more. In vivo testing in rat cortex validated this design, showing significantly lower insertion energy and reduced cortical dimpling compared to conventional equal-length shank MEAs.
My Contributions
I contributed to both the experimental and analytical components of this project and supported the integration of NeuroNexus designs into our research workflow. I was involved in in vivo data collection during mechanical insertion testing, including force–displacement measurements and analysis of cortical dimpling. I assisted in calculating insertion energy as a novel quantitative metric of implantation trauma, enabling direct comparison between MEA configurations. This work demonstrates a fabrication-compatible, industry-scalable design that passively reduces cortical trauma during MEA implantation, and lays the groundwork for future high-density, low-injury neural interface platforms.
