A　terahertz　metamaterial　refractive　index/thickness　sensor　with　flexible　substrate,　exhibiting　low-frequency　Fano　resonance　and　high-frequency　electromagnetically　induced　transparent　(EIT)　resonance,　is　proposed.　The　physical　formation　mechanisms　of　Fano　and　EIT　resonances　are　investigated　by　calculating　the　electromagnetic　field.　Simulated　results　demonstrate　that　the　refractive　index　sensing　sensitivity　based　these　two　resonances　are　up　to　60　and　100　GHz/RIU,　and　the　thickness　sensing　sensitivity　are　up　to　1　and　1.7　GHz/μm,　respectively.　Furthermore,　the　proposed　sensor　was　fabricated　using　femtosecond　laser　etching　technology,　and　its　sensing　performance　was　verified　by　the　experimental　results　that　it　can　distinguish　different　liquids　and　detect　the　polyimide　film　with　different　thicknesses　less　than　180　μm.　The　remarkable　performances　make　the　proposed　metamaterial　sensor　has　feasible　capability　for　biological　and　chemical　sensing　in　terahertz　range.　©　2009-2012　IEEE.