A novel MEA architecture with excellent electrophysiological recordings is presented, where planar microelectrodes are replaced by localized 3 × 3 arrays of mushroom-shaped microstructures. The micro-mushrooms in this islets configuration are not for membrane engulfment but rather for somata entrapment and neurites embracement. As extracellular signals have a significant contribution from axons initial segment, this MEA design also addresses the electrode-neurites electrical coupling. These islets act as strong physical cues, causing topotaxis and increasing by two-fold the probability for somata to localize in the islets. We carry this topotaxis study not only with rat cortical neurons but also with humanderived SH-SY5Y cells.

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Highly-ordered TiO2 nanotubes (NTs) have gained much importance for application in hydrogen production by water splitting (photoelectrochemical cells) and the dye-sensitized solar cells (DSCs) [1,2]. The TiO2 NTs can be synthesized using a titanium foil in fluoride containing electrolytes via electrochemical anodization method. The NTs geometry depends on different anodizing parameters (electrolyte type and concentration, pH, time, applied potential) that determine the tube features (length, pore diameter, wall thickness, etc.). TiO2 NTs arrays were synthesized by an electrochemical anodization of a Ti foil (two-electrode cell) with an anodization potential of 60 V for 17 h, in an ethylene glycol solution containing NH4F (0.3 wt%) and H2O (2 wt%) at room temperature [3]. It was implemented, prior to the anodization, three different pre-treatments on the Ti foil: a chemical etching with 4% HF solution, a mechanical polishing and an electropolishing in a H2SO4/HF solution, with an applied potential of 10 V during 4 min. In this work, it is described the impact that a simple pre-treatment has to the template growth and final thickness after a single anodization step, as well as on the template quality (NTs organization and domain size). For this purpose, the topography of the Ti surface (prior to the anodization) with these 3 pre-treatments and an asrolled Ti sample was investigated by Atomic Force Microscopy. Roughness studies were compared with the NTs template thickness and organization quality. Highly self-ordered arrays of TiO2 NTs were obtained, and found that pre-treatments that decrease the Ti surface roughness are a crucial step in the TiO2 NTs electrochemical anodization syntheses for obtaining: a fast NTs growth attaining a highest final template thickness; an enhancement in the NTs organization quality reaching highly ordered hexagonal NTs arrays in larger areas [3].

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