3D-Printed Carbon Electrodes for Neurotransmitter Detection.

Implantable neural microsensors have significantly advanced neuroscience research, but the geometry of most probes is limited by the fabrication methods. Therefore, new methods are needed for batch-manufacturing with high reproducibility. Herein, a novel method is developed using two-photon nanolithography followed by pyrolysis for fabrication of free-standing microelectrodes with a carbon electroactive surface. 3D-printed spherical and conical electrodes were characterized with slow scan cyclic voltammetry (CV). With fast-scan CV, the electrodes showed low dopamine LODs of 11±1 nm (sphere) and 10±2 nm (cone), high sensitivity to multiple neurochemicals, and high reproducibility. Spherical microelectrodes were used to detect dopamine in a brain slice and in vivo, demonstrating they are robust enough for tissue implantation. This work is the first demonstration of 3D-printing of free-standing carbon electrodes; and the method is promising for batch fabrication of customized, implantable neural sensors.