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We demonstrate new fabrication technologies for 3D microelectrode platforms, fully realized for several 3D multi-functional biosystems. The microfabrication technology involves 3D metallized microtowers realized by 3D printing, metal evaporation, and coarse biocompatible lamination to insulate the traces. Electrospun 3D nanofiber scaffolds (NFSs) are coupled to the microelectrodes to provide additional functionality. The scaffolds were formed via electrospinning two types of nanofibers: ~200-500 nm PET, a hydrophobic polymer, and ~100 nm PVA/PAA, a hydrophilic co-polymer. PVA/PAA nanofibers had consistent diameters without beading and were used in subsequent experiments. Impedance measurements before, 651.3 $\text{k}\Omega $ , and after, 659.4 $\text{k}\Omega $ , deposition of PVA/PAA remains unchanged, indicating enhanced functionality without interfering with the electrical characteristics of the 3D MEAs. Silver nanoparticles (Ag NP) were embedded as model drug compounds in the PVA/PAA-NFS to demonstrate the potential of the 3D MEA as a biosensor and drug delivery system. TEM and antimicrobial studies demonstrated ~5-15 nm Ag NP within the PVA/PAA-NFS, which was potent to Acinetobacter baumannii and Escherichia coli. Fine 3D insulation atop the microtowers is achieved using a drop-casted/spin-coated 3D layer of Polystyrene (PS), which is laser micromachined to realize $50\times 50\,\,\mu \text{m}^{{2}}\,\,3\text{D}$ microelectrodes with impedance properties similar to other reported approaches. [2019-0043] [ABSTRACT FROM AUTHOR]

Microelectrode Arrays are established platforms for biosensing applications; however, limitations in electrode impedance and cell-electrode coupling still exist. In this paper, the SNR of $25~\mu \text{m}$ diameter gold (Au) microelectrodes was improved by decreasing the impedance with precision electrodeposition. SEM determined that N-P Pt. microelectrodes had nano-porous structures that filled the insulation cylinders. EIS, CV, and RMS noise measurements concluded that the optimized electrodeposition of N-P Pt. led to a lowered impedance of $18.36~\text {k}\Omega \pm 2.6~\text {k}\Omega $ at 1 kHz, a larger double layer capacitance of 73 nF, and lowered RMS noise of $2.08 \pm 0.16~\mu \text{V}$ as compared to the values for Au of $159~\text {k}\Omega \pm 28~\text {k}\Omega $ at 1 kHz, 17nF, and $3.14 \pm 0.42~\mu \text{V}$ , respectively. Human motoneurons and human cardiomyocytes were cultured on N-P Pt. devices to assess their biocompatibility and signal quality. In order to improve the cell-electrode coupling, a precision plating technique was used. Both cell types were electrically active on devices for up to 10 weeks, demonstrated improved SNR, and expected responses to precision chemical and electrical stimulation. The modification of Au microelectrodes with nanomaterials in combination with precision culturing of human cell types provides cost effective, highly sensitive, well coupled and relevant biosensing platforms for medical and pharmaceutical research. [2018-0187] [ABSTRACT FROM AUTHOR]