Rapid Makerspace Microfabrication and Characterization of 3D Microelectrode Arrays (3D MEAs) for Organ-on-a-Chip Models.

Integrated sensors in "on-a-chip" in vitro cellular models are a necessity for granularity in data collection required for advanced biosensors. As these models become more complex, the requirement for the integration of electrogenic cells is apparent. Interrogation of such cells, whether alone or within a connected cellular framework, are best achieved with microelectrodes, in the form of a microelectrode array (MEA). Makerspace microfabrication has thus far enabled novel and accessible approaches to meet these demands. Here, resin-based 3D printing, selective multimodal laser micromachining, and simple insulation strategies, define an approach to highly customizable and "on-demand" in vitro 3D MEA-based biosensor platforms. The scalability of this approach is aided by a novel makerspace microfabrication assisted technique denoted using the term Hypo-Rig. The MEA utilizes custom-defined metal microfabricated microelectrodes transitioned from planar (2D) to 3D using the Hypo-Rig. To simulate this transition process, COMSOL modeling is utilized to estimate transitionary forces and angles (with respect to normal). Practically, the Hypo-Rig demonstrated a force of ~40N, as well as a consistent 70° average angular transitionary performance which matched well with the COMSOL model. To illustrate the scalability potential, 3 × 3, 6 × 6, and 8 × 8 versions of the device were fabricated and characterized. The 3D MEAs, demonstrated impedance and phase measurements in the biologically relevant 1 kHz range of 45.4 kΩ, and -34.6° respectively, for polystyrene insulated, ~70 μ m sized microelectrodes.