Auxetic tissue engineering scaffolds with nanometric features and resonances in the megahertz range

In this study we present an improved approach for the development of auxetics based on the use of deep reactive ion etching (DRIE) after a high-precision mask fabrication procedure. The whole process stands out for its precision (reaching nanometric detail), for the high aspect ratio (AR) attainable and for the possibility of promoting mass production. The quality of the proposed strategy is verified by the manufacture of an auxetic cantilever and bridged structures using two common planar auxetic geometries. The present process significantly increases the precision and AR of the micro-auxetics obtained when compared to state-of-the-art micromachining procedures and solves common challenges linked to structure adhesion to the substrate. The potential of the manufactured structures for the development of resonant structures is analyzed by means of finite-element-method-(FEM) based simulations, showing resonances in the megahertz range. A final application example, linked to monitoring cell culture processes upon auxetic scaffolds, is also proposed and analyzed by computational procedures. The initial cell culture results are also included and help to validate the scaffolds obtained and the materials used for future tissue engineering studies.