The application of nanotechnologies for a novel type of position particle detector is the aim of NanoChanT project. Titanium dioxide (TiO2) nanowires are grown in an highly ordered array of parallel nanochannels in an alumina template. The template is obtained from the controlled anodization of an aluminum foil that produces regular pores. Depending on anodization conditions, the diameter of the pores ranges from 20 to 200 nm with 40 to 500 nm pitch. After doping, a pn junction can be obtained from each of the TiO2 nanowire. The junction is inversely polarized and is sensitive to the passage of charged particles. The charge produced in groups of nanowires is collected by metal pixels and readout by CMOS electronics. GEANT4 has been used for the simulation of the interaction of ionizing particles with the detector. The simulation at the nanoscale level is of fundamental importance in the design of the geometry of the device, in order to choose the best compromise between the smallest detectable charge produced in a readout channel and the maximum achievable spatial resolution. The current design and status of the detector and the considerations driven by the simulation with GEANT4 are presented.