In　this　study,　a　rapid,　convenient　and　in　situ　applicable　Cu2+　sensor　was　constructed　based　on　a　luminescent　layer　immobilizing　Ru　(bpy)　3Cl2　with　a　maximum　wavelength　of　600　nm,　which　was　taken　as　the　reference　background　light.　The　luminescence　intensity　of　the　layer　was　kept　constant　and　isolated　from　the　oxygen　change　in　the　solution　due　to　the　hybrid　polyacrylonitrile-dimethylsulfoxide　used　in　the　immobilization　of　the　Ru(bpy)3Cl2.　The　CdTe　quantum　dot　(QD)　luminescence,　with　a　maximum　wavelength　of　520　nm,　was　quenched　to　different　degrees　depending　on　the　Cu　2+　concentration　in　the　solution.　Using　a　commercial　camera,　different　colors　could　be　captured　in　different　Cu2+　concentrations.　This　color　change　was　caused　by　the　composite　light　with　stable　luminescence　from　the　Ru　(bpy)3Cl2　layer　and　the　changeable　fluorescence　of　the　CdTe　QDs.　Sensor　characteristics,　including　the　co-existing　ions,　oxygen　content,　temperature　effect,　and　sensor　stability,　were　investigated.　©　2011　The　Royal　Society　of　Chemistry.