Field manipulation of electromagnetically induced transparency analogue in terahertz metamaterials for enhancing liquid sensing

•A method of manipulating the electric field for enhancing liquid sensing is reported.•The electric field tightly confined inside the structure by optimizing the fully-enclosed metamaterial structure design.•The effective regional substrate etching realize maximumly light-matter interaction.•The measurements reveal significantly improve in sensitivity of 0.312 THz/RIU, which is 9.8 times to that without etching by contrast.