Authors:

Aidan Hirsch

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About Paper:

There are currently 5.6 million people diagnosed with some form of limb paralysis in the world. Invasive brain machine interfaces (BMI) can provide these patients with solutions such as basic typing capabilities through decoding neural signals, however a medical procedure capable of restoring functionality is not realized yet. Previous BMI efforts could not achieve a substantial restoration of limb function due to foreign body response (FBR) effects, which degrade the signal quality by decreasing the signal to noise ratio (SNR). Literature suggests shrinking the dimensions of an electrode results in a lesser FBR from the brain. Ultramicroelectrode arrays (UMEAs), a class of extremely small BMIs, trigger the brain's FBR to a point where invasive implantations can be left in for six months to a year before degradation. The UMEAs utilized in this study are coated with a sputtered iridium oxide film (SIROF) to ensure high stimulation and recording performance. However, the FBR still causes degradation of this coating, resulting in the UMEA gradually becoming ineffective for long-term stimulation purposes. Our third generation (G3) UMEAs were implanted in Sprague-Dawley rats for a period of sixteen weeks and the degradation of the SIROF coating was measured using electrochemical impedance spectroscopy (EIS). By modeling the physical characteristics of the UMEA from the EIS data, we can predict the amount of degradation of the SIROF coating at a specific timeframe. Being able to quantitatively model the amount of degradation on the UMEA allows us to understand the failure modes and improve longevity in vivo. Keywords: Ultramicroelectrode Arrays; Electrochemical Impedance Spectroscopy; SIROF coating; Neural Interfaces; Neuroprostheses

Source:

Purdue University / 2025

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Co-authors:

Aidan Hirsch