Direct submicron patterning of titanium for bone implants

Abstract

Recent research evidences the strong modulatory role of controlled submicron and nanoscale topographies on stem cells fate. To harness these physical surface cues for clinical applications, fabrication of nano-and submicron patterns on clinically relevant biomaterials is greatly needed. In this study, an electron beam lithography method for direct patterning (i.e., no use of masters/imprinting steps) of titanium in the submicron range was developed. The process required the use of an etch mask consisting of a double layer of SiO 2 and Al, and the positive AR P-6200.04 electron beam resist. An optimum electron beam dose of 288 μC/cm 2 was established for writing the desired patterns. The transfer of the patterns into the titanium substrates was achieved by three different steps: inductively coupled plasma etching of the mask in BCl 3 /Cl 2 followed by reactive ion etching of titanium in SF 6 /CHF 3 /O 2 and a final wet etch of mask residue. Highly ordered arrays of titanium pits with submicron diameters were produced with high reproducibility. This method provides great versatility in pattern design, direct transfer into titanium and increased control of titanium pattern features at submicron to nanoscale enabling clinically relevant and systematic studies on pattern-induced cellular responses.

Meta-biomaterials

“…In addition to AM approaches, lithography-based approaches such as electron beam-based nanolithography supplemented with inductively coupled plasma etching could be used for fabricating nanofeatures in the range of a few hundred nanometers. 102 Between themselves, these techniques could create almost any desired geometrical design with a high level of precision and repeatability. There is, however, a major caveat in all these approaches: most advanced nanopatterning techniques are only applicable to flat surfaces.…”

Differential Etching of Rays at Wood Surfaces Exposed to an Oxygen Glow Discharge Plasma

“…Uniformity or good lateral resolution of plasma etching is needed to create reproducible microstructures in materials such as silicon wafers [23]. Such etch uniformity is more easily achieved with solid materials such as silicon and metals [23,44], but it has also been achieved with porous silicon [45]. Wood is a highly porous material depending on its density and there is great variation in its microstructure [38].…”

Cost and Time Effective Lithography of Reusable Millimeter Size Bone Tissue Replicas With Sub‐15 nm Feature Size on A Biocompatible Polymer

“…However, self‐assembly methods lack precise control of shape and size of the nanopatterned features and flexibility on the choice of the environment. On the other hand, the rapid development of top‐down lithographic methods, such as photolithography, [ 21–23 ] electron beam lithography, [ 24,25 ] soft lithography, [ 22,26 ] and nanoimprinting lithography, [ 27,28 ] has led to the fabrication of a variety of synthetic surfaces with well‐defined but simple geometrical features, such as pillars, squares, bumps, and grooves. [ 29–31 ] In general, bottom‐up and top‐down fabrication approaches are unable to reproduce the exact nano‐ and microscale morphology and chemistry of the bone tissue, and therefore are limited in their ability to produce biomimetic surfaces that accurately control cell behavior.…”