Adhesion and growth of electrically-active cortical neurons on polyethyleimine patterns microprinted on PEO-PPO-PEO triblockcopolymer-coated hydrophobic surfaces

This paper describes the adhesion and growth of dissociated cortical neurons on chemically patterned surfaces over a time period of 30 days. The presence of neurons was demonstrated by measurement of spontaneous bioelectrical activity on a micropatterned multielectrode array. Chemical patterns were prepared with a combination of neurophobic layers of polyethylenoxide-polypropylenoxide-polyethylenoxide (PEO-PPO-PEO) triblockcopolymers adsorbed onto hydrophobic surfaces and neurophilic microprinted tracks of polyethylenimine (PEI). Results showed that commercially available PEO-PPO-PEO triblockcopolymers F108 and F127 (Synperonics, ICI) significantly reduced the adhesion of neuronal tissue when adsorbed on hydrophobic Polyimide (PI) and Fluorocarbon (FC) surfaces over a time period of eight days. In general, both F108- and F127-coated PI displayed equal or better neurophobic background properties after 30 days. Viability of neuronal tissue after 30 days on PEI microprinted F108- and F127-coated PI was comparable with relatively high viability factors between 0.9 and 1 (scale from 0 to 1). Summarizing, the strategy to combine the neurophobic adsorbed triblock-copolymers F108 and F127 onto hydrophobic surfaces with neurophilic microprinted PEI resulted in relatively long-term neuronal pattern preservation with high numbers of viable neurons present after 30 days

Structured ZnO-based contacts deposited by non-reactive rf magnetron sputtering on ultra-thin SiO2/Si through a stencil mask

In this paper, we study the localized deposition of ZnO micro and nanostructures deposited by non-reactive rf-magnetron sputtering through a stencil mask on ultra-thin (10 nm) SiO2 layers containing a single plane of silicon nanocrystals (NCs), synthetized by ultra-low energy ion implantation followed by thermal annealing. The localized ZnO-deposited areas are reproducing the exact stencil mask patterns. A resistivity of around 5×10−3 Ω cm is measured on ZnO layer. The as-deposited ZnO material is 97% transparent above the wavelength at 400 nm. ZnO nanostructures can thus be used as transparent electrodes for Si NCs embedded in the gate-oxide of MOS devices

Neuronal adhesion and growth on polyethylenimine tracks microprinted on polyethyleneoxide-polypropyleneoxide coated surfaces

Adsorbed layers of polyediylenoxide-polypropylenoxide (PEO-PPO) blockcopolymers were tested as neurophobic background coatings in neuronal patterning studies over a time period of 30 days. Microprinted tracks of polyethylenimine (PEI) were used as the neuron-adhesive part of the pattern. Results showed that PEO-PPO surfactants F108 and F127 (Synperonics, ICI) significantly reduced the growth of neuronal tissue when adsorbed on Polyimide and Fluorocarbon surfaces up till 8 days. Also survival of neuronal tissue was not negatively affected by the PEO-PPO. Viability of the cultures was assessed after 30 days and showed viability factors above 0.9 (scale 0 to 1)

Towards Reliable 100-Nanometer Scale Stencil Lithography on Full Wafer: Progress AND Challenges

We have fabricated new and robust nanostencil membranes for the surface patterning of 100-nm scale Al wires on full wafer scale. The stencil membranes are mechanically reinforced with corrugations, making them more stable against accumulated stress. The apertures in the stencil are fabricated by a combination of UV lithography and focused ion beam milling, ranging from sub-100 nm to several microns. The presence of a gap between the stencil aperture and the substrate results in a blurring of the pattern, on the order of 100-300 nm. A gentle Al dry etch is applied to reduce the blurring, achieving sub-100 nm wide structures. 80 nm wide nanowires connected to micrometer-scale contact pads are fabricated and shown. The clogging of the stencil apertures is quantified and a cleaning procedure is presented