Progress is reported on the development and testing of Monolithic Active Pixel Sensors (MAPS) for a Si-W ECAL for the ILC. Using laser and source setups, a first version of the sensor has been characterised through measurements of the absolute gain c
alibration, noise and pedestal. The pixel-to-pixel gain spread is 10%. Charge diffusion has been measured and found to be compatible with simulation results. The charge collected by a single pixel varies from 50% to 20% depending on where it is generated. After adding detector effects to the Geant4 simulation of an ILC-like ECAL, using the measured parameters, the energy resolution is found to be 35% higher than the ideal resolution, but is still lower than the resolution obtained for an equivalent analogue ECAL.
