Microelectromechanical system apparatus and methods for surface acoustic wave switching are disclosed. The control unit controls the power supply unit to output power that is less than a predetermined value if the predetermined object is detected, and the predetermined object does not include a chargeable object. The insert comprises a number of units arranged in rows, which units together with the walls of the chamber define a channel for a fluid. Preferably, the mosaic polypeptides contain antigenic epitopes from the core protein, NS3 protein, and NS4 protein. For identical dimensions, the underwater acoustic transducer makes it possible to decrease a central frequency of emission and to increase bandwidth. A non-oxidizing gas is flowed into the chamber to prevent instant and subsequent oxidation on the copper surface.