Most of the existing remote controllers use primary batteries such as lithium batteries, dry batteries, etc. as power supplies. Such remote controllers may be not energy-saving and environmental friendly and meanwhile may make a great waste in term of energy. Besides, they may introduce a burden of purchasing and replacing batteries to users. Especially in the field of bathware, the using environment of the remote controller is relatively harsh; the corrosiveness by humid environment is particularly obvious to batteries and would reduce the lifetime of batteries. Thus, in the field of smart bathware, battery-free is now one of the most critical and the most important technical challenges to be solved.