Bioengineering Strategies towards Multielectrode Arrays for Chronic In Vivo Neural Recording and Chemical Sensing

Microelectrode array (MEA) devices, placed in the nervous system to record and modulate neuroactivity have demonstrated success in neuroscience research and neural prosthesis applications. Functionalizing the microelectrode sites on MEAs to enable electrochemical sensing adds additional dimensions of information, and such multimodal MEAs present tremendous potential for understanding neural circuits and treating neurological diseases. In this talk, I will introduce the methods by which we enable chemical sensing from MEAs. By incorporating nanocarbon into the conducting polymer electrode coating, we achieved direct detection of electroactive species such as dopamine, melatonin, and serotonin. By immobilizing enzymes or aptamers on nanostructured electrodes, we achieved multisite detection of glutamate, GABA, and cocaine. Multisite and multiple analyte detection along with neural recording have been demonstrated with these MEAs. Currently, the chronic recording and sensing performance of implantable MEAs is sub-optimum due to material limitations and undesired host tissue responses. Quantitative histology, explant analysis, and 2-photon imaging revealed biofouling, neuronal damage, inflammation, and oxidative stress at the site of implants. Meanwhile, material degradation also contributes to device failure. We use several bioengineering strategies to minimize these failure modes. First, materials and devices that mimic the mechanical properties of the neural tissue have been developed and shown to significantly improve device-tissue integration. Secondly, biomimetic coatings and drug delivery have been applied to reduce biofouling and inflammatory responses. These approaches may be combined to achieve long-term and high-fidelity neural recording and chemical sensing.