The invention relates to the use of a shape memory effect (SME) material, such as nitinol, in an actuator for effecting rotation of an electrosurgical instrument. The actuator may be part of a control mechanism for rotating a tip of an electrosurgical instrument relative to a flexible shaft that encases components of the instrument as they are conveyed along an instrument channel of a surgical scoping device, such as an endoscope, bronchoscope, laparoscope, gastroscope, or the like.