Synthesis of vertically aligned titanium dioxide nanotubes on microcantilevers for new nanostructured micromechanical sensors for explosive detection

The use of microcantilevers as sensors for the detection of molecules is a promising method to reach low sensitivity. However, small surface area of conventional microcantilevers limits the sensitivity of the method. To increase the surface density of adsorption sites, we propose a method to modify microlevers with high surface area nanotubular titanium dioxide structures. This nanostructuration is achieved by an accurate control of the parameters of a-two-steps synthesis. The first step consists of the deposition, by a magnetron sputtering method, of a thick and dense metallic titanium layer on the silicon microcantilever. In the second step, this layer is anodized to form the aligned titanium dioxide nanotubes array. The influences of the deposition speed on the titanium film quality and of the anodization parameters on the nanotubes formation are discussed. The synthesis conditions are optimized to adjust the titanium dioxide nanotubes synthesis to the micrometric dimensions of the microcantilevers. Finally the systems modified with this nanotubular structure show a surface enhancement factor of ca. 70 and an explosive molecule absorption improved by 100.