Using 4-acryloylamidobenzo-18-crown-6 as a recognitor, a Pb2＋ sensitive smart bending bigel containing a response layer and a nonresponse layer was developed. Colloidal crystals were introduced into the bigel as a color-coded layer for visual detection. The bigel bended corresponding to Pb2＋ concentration when it was immersed in the Pb2＋ solutions. The changes of Pb2＋ concentration in a range of 0.1～10 mmol/L can be distinguished by the naked eyes according to the bending degree of the bigels. Furthermore, the double-layer structure of the bigel can counteract the disturbance of non-specific factors such as metal ions (Mg2＋, Na＋ and Li＋) and temperature. Based on our findings, a novel visual detection method can be established for Pb2＋, which will be utilized in Pb2＋ primary analysis on the spot.

Key words: smart bending bigel, gelled colloidal crystal, lead ion, visual detection