Most of the DNA chips available on the market are based on external or internal optical detection (fluorescence or chemiluminescence) and need a bulky chip reader (optics, laser, camera or PMT). We will present a new detection strategy using direct electrochemical detection of DNA hybridisation using conductive polymers grafted on an active silicon chip. We will report results on the first step of the fabrication process and emphasis on full wafer electropolymerisation of DNA probes on modified CMOS technology.