A wind turbine blade with strain sensing functionality includes a surface structure, a block sensor unit including an optical sensor mechanism for sensing strain in the blade, and an intermediate connection plate positioned in between the optical sensor mechanism and the surface structure. The intermediate connection plate is adhesively connected to the surface structure and connected to the optical sensor mechanism. The modulus of elasticity of the intermediate connection plate is similar to or less than the modulus of elasticity of the surface structure. A wind turbine, block sensor unit and uses thereof are also contemplated.