Optical Nanoantennas Integrated with 3D Microelectrode Arrays: Hybrid Photonic-Electronic Modalities for Nano-Bio Interfacing

The human body is dynamic and understanding such complexity for accurate diagnostics and therapies remains a challenge due to lack of minimally-invasive biotechnologies capable of long-term measurements of various biochemical and bioelectrical signals simultaneously from single cells to cell networks. Biocompatibility is a major challenge but recent advancements in micro- and nano-fabrication has shown that patterned protruding pillars from surfaces at the micro- and nano-scale can mimic intrinsic biological structural cues to trigger strong cell adhesion, engulfment, and growth, providing a means by which to engineer the biocompatibility for controlled cell-device bio-interfaces. Here, we sought to leverage the unique biocompatibility of engineered three-dimensional (3D) features with integrated biochemical and bioelectrical sensor arrays to create a multi-modal platform for complex systems biological research. For the biochemical sensor, we introduced a tunable optical nanoantenna that is driven wirelessly by incident laser light (photons) to create a highly localized electric field capable of enhancing the photon scattering rate of nearby chemical bonds, a unique signature that provides a means to fingerprint the local biomolecular ensembles depending on the color of detected scattered photons. By a novel scalable fabrication technique, we merged such nano-sensors with 3D micropillar electrode arrays to create a device with hybrid biophotonic and bioelectronic functionality. We revealed the unique optical properties by micro-reflectance measurements and numerical simulations and verified by spectroscopic measurements a million-fold enhancement to the scattered photon signature from a standard chemical monolayer. We showed favorable bioelectrical properties by electrochemical impedance spectroscopy and cyclic voltammetry, revealing a stable electrochemical interface and reduced resistance due to 3D geometry enabling improved transduction of electrical signals, useful for higher signal to noise ratios in bioelectrical measurements. Overall, we demonstrated the scalable fabrication and unique optical and electrical properties suitable for next generation multi-modal bio-interfacing platforms.