This study deals with experimental methods dedicated to the determination of the liquid chemical potential in heterogeneous media. Various measurement techniques are proposed including a new mechanical method based on the expansion of the air-vapor atmosphere surrounding a sample. From the large range of materials under investigation (soil, wood, gel, agro-product, biological tissue), various micro-structures are investigated. Thus, liquid/solid interactions occurring at the interface scale involve several physico-chemical phenomena that can all be interpreted through the concept of chemical potential. The dependence of the liquid chemical potential on the liquid content is established over the whole range of energy. Eventually, extrapolation of the results towards the low values of chemical potential is analyzed and a modeling approach is proposed. Even if the results presented concerns essentially a water phase, the principles are applicable to several other fluids.