Stimuli-responsive polymer is one of the hot research topics in material science. These polymers are able to respond to external stimulation, such as light, molecules, redox, pH, temperature and so on. They undergo physical or chemical changes, for example, gel-sol transition and change of volume, so they can be widely applied in controlled drug release and biosensors. Voltage stimulation can change the host-guest interaction through electron transfer reactions to add or remove electrons of host or guest molecules. This type of stimulation does not bring in extraneous redox, so it is a clean and simple method. Additionally, it can be used in biological system for it is actually one type of redox, the most common action type in biomedicine. Therefore, much attention has been attached to voltage-responsive systems. β-cyclodextrin and ferrocene can form inclusion complex by host-guest interaction when mixed together, and this interaction can also be regulated by voltage. Voltage-responsive system based on β-cyclodextrin and ferrocene is the most attractive one, because raw materials are commercially available, biologically compatible and can be modified to polymers easily. This paper investigates the recent work related to this system and summarizes four main parts, from principle, structure and characterization to applications. Moreover, the development and improvement of this system are discussed.

Contents
1 Introduction
2 Basic principle of systems based on β-cyclodextrin and ferrocene
3 Structures of systems based on β-cyclodextrin and ferrocene
4 Characterization of systems based on β-cyclodextrin and ferrocene
4.1 Cyclic voltammograms
4.2 Other methods
5 Applications of systems based on β-cyclodextrin and ferrocene
6 Conclusion and outlook