(I-328) Flexible electrochemical neural probes for in vivo recording of neurotransmitters

Introduction:: Catecholamines are a significant focus in research because they play a critical role
in the brain's "reward" system, although their precise function is not yet fully comprehended. The
quantification of catecholamines are vital as they regulate all cognitive processes in the brain and
can aid in early detection, diagnosis, monitoring, and therapeutic interventions for complex
neural disorders. The use of implantable neural interfaces is essential in expediting progress in
neuroscience research and the practical application of clinical neurotechnologies.
Electrochemical sensors offer several advantages for measuring catecholamines, including high
sensitivity and selectivity, rapid response time, minimal sample preparation, non-invasiveness,
and portability

Materials and Methods:: The proposed design in Figure 1 will be used to create the sensor. It includes a working electrode and a reference electrode with a reference membrane. The reference electrode is shared between the platinum electrodes and will be formed on a parylene C substrate that is 10-20 μM thick. The platinum electrodes have a radius of 600 μM and a thickness of approximately 200 nm. The sensing membrane will be applied to the circular area of the platinum contact using drop-casting.

Results, Conclusions, and Discussions:: For in vivo recording, parylene's flexibility is essential because it enables implanted devices to adapt to the shape of the brain or muscles and move with it without harming the surrounding tissue. While many electrodes for in vitro catecholamine sensing utilize coatings made of enzymes, aptamers, and antibodies to increase their sensitivity, these coatings are prone to biofouling and quick degradation, which reduces the sensor's lifespan in vivo. As a result, we are using a label-free surface modified Pt electrode, which has been shown to be durable during long-term implantation, Figure 1. The expected peaks potential for different catecholamines are: Epinephrine (EP): around 0.1-0.3 V, Norepinephrine (NE): around 0.1-0.2 V, Dopamine (DA): around 0.2-0.4 V. We utilize cyclic voltammetry and square wave voltammetry for direct electrochemical detection of catecholamines. For acetylcholine and pH, we are depositing a sensing membrane comprising an ionophore on the working electrode.

Flexible neural probe module for in-vivo recording of different neurotransmitters can be developed on the parylene C support. Electrodeposition was successfully used to modify the surface of platinum leads to add selectivity to the electrode response.


Acknowledgements (Optional): : We would like to acknowledge the Center for Autonomic Nerve Recording and Stimulation 340 Systems (CARSS, 1U41NS129514-01)

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