Here we report an example of a general strategy for the immobilization of various different photochromic spiropyran molecules on eco-friendly cheap nanomatrix. The spiropyrans are encapsulated in calcium salt oligomers-based gels by centrifugation, forming an inorganic oligomer-based gelatinous photoswitchable hybrid material. Ca²⁺ is also used to regulate the optical properties of spiropyrans through chelation. The oligomer-based gel can not only provide the space required for photoisomerization, but also reduce the interference of the surrounding environment on the photochromic properties. Moreover, a practical paper-based and colloidal flexible substrate platform is constructed for the removal and naked-eye detection of liquid and gaseous hydrazine at room temperature based on the reactivity of the formyl group on spiropyrans loaded in Ca₃(PO₄)₂ oligomers. This general strategy can be used for other inorganic oligomer-based molecular switches and sensing systems.