During decommissioning, the initial cartography of all surfaces is crucial for identifying potential future waste based on its radiation level. contamination detectors should be calibrated in terms of emission flux or Bq.cm-2 using suitable surface sources. Current standard sources, complying with ISO 8769 (Reference Sources-Calibration of Surface Contamination Monitors ), lack representativeness since they are only made of aluminium and have a limited surface area. This research seeks to produce flexible, traceable surface sources for alpha and beta emitters with low radiation self-absorption. While the existing sources are produced by adsorption on the aluminium surface, we aim to have strong chemical bonds due to the grafting on the surface. A novel functionalisation strategy involving spacer chemicals was developed to provide these sources. We have studied two substrate types: polymeric sources that can be molded into complex shapes and flexible aluminium foils that can be compared to existing ISO 8769 sources. This contribution will focus on aluminium substrate functionalisation . It involved choosing bi-functional compounds that can bind to a radionuclide on one end and be grafted onto aluminium with the free functional group of the compound on the other end. Because the radioactivity is chemically bound to their surfaces, these sources are meant to be non-contaminating and easy to use on-site. Our calibration sources can also be used to assess the detector's performance in front of a curved radioactive surface. Three bi-functional compounds were identified and the three main surface functionalisation steps were optimized. The first step is cleaning, to remove all the residues from the substrates. Then etching proceeded to release hydroxide functions. Next, the etched samples are immersed in the bi-functional compound solution. The influence of the reaction time, temperature, and drying conditions were studied. After the functionalisation, the inactive samples were characterised. The Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy has demonstrated that the ligand molecules are successfully grafted to the aluminium surface. The Scanning Electron Microscopy (SEM) images revealed a change in surface morphology following each functionalisation step. In addition, X-ray Photoelectron Spectroscopy (XPS) was utilised for complementary analysis. Finally, radionuclide binding experiments were conducted with Eu-152 as trivalent Eu is an excellent chemical analog for trivalent actinides such as Am-241. Liquid scintillation counting and autoradiography were used to quantify the radionuclides bound to the grafted surface and check the uniformity of the sources.