Surgical tools having a two degree-of-freedom wrist, wrist articulation by linked tension members, mechanisms for transmitting torque through an angle, and minimally invasive surgical tools incorporating these features are disclosed. The body has a working surface and an interface surface, and may be joined to a metallic substrate. Drainage body connecting elements are proposed for connecting drainage bodies, which comprise two pegs which are connected via a web can each be inserted in a receiving orifice of a drainage body so the two drainage bodies can be connected together via the web. In conclusion there is a filling of a liquid crystal material in the space whereby a cell, or film is created. In the driving method, wall charges concentrate on the center portion of the discharge cell during an auxiliary discharge generated between the auxiliary electrode pair.