The objective of this project is to develop nano/micro sensors to aid the development of fuel cells. The local internal temperature, gas species and humidity distribution constitute critical conditions determining the efficiency and reliability of a fuel cell. However, detailed mapping of these conditions without interference with the membranes' behaviour is a challenging task. By integrating an assembly of nano/micro sensors directly on to the membrane surface inside the stack of the fuel cells to monitor the operating parameters, completely new knowledge of the physical/chemical state of the system can be established and applied to on-line adjustments to meet optimal performance. The generic output of this unified project will be an increased activity on fundamental research within the sensor field, a novel platform for non-silicon based nano/micro fabrication platform as well as the ability to improve the performance of existing fuel cells by correlating optimal performance with experimental determined local humidity, gas species O2/H2/CO concentrations, and temperature within a working fuel cell.