Fabrication and Characterization of a 3D Printed, MicroElectrodes Platform With Functionalized Electrospun Nano-Scaffolds and Spin Coated 3D Insulation Towards Multi- Functional Biosystems

Abstract

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]