Abstract: An actuator converts an input movement to a control movement with a bistable action. The actuator is operable to provide a first control movement in response to a first input movement and a second control movement immediately upon the second input movement. The actuator is embodied in a foot switch and in an air switch.

Abstract: An optical fibre sensor includes an elongate optical fibre and a casing for the fibre, the casing including a first elongate, flexible and substantially inextendable strip portion and a second elongate, flexible strip portion arranged so that the fibre therebetween is sandwiched between the strip portions, at least the first strip portion being provided with a series of transverse ridges for engaging the fibre, with grooves being formed between the ridges, and the other strip portion being adapted to bend the fibre into the grooves upon pressing together of the strip portions.

Abstract: A pressure operated switch has a bistable or multi-stable latching mechanism disposed between a bellows unit and an electrical switch. The latching mechanism has two relatively axially moveable elements which extend and contract with subsequent operations of the bellows unit to provide the bistable action.