Abstract: A device and a method are disclosed for creating a virtual keyboard, mouse, or position detector. The device is an electronic keyboard that detects the position of a user's finger. The position of a user's fingers are detected by sending out a light beam parallel to the surface of, for example, a desk, and then detecting the position of a user's finger as the light beam is blocked by the finger. The position and movement of the user's fingers determine which key is to be struck or in which direction to move the pointer.

Abstract: A mixing system comprising (1) a mixing cartridge comprising a housing containing: (a) an internal chamber, (b) access means for entry of a liquid into the internal chamber, and (c) a magnetically movable detached mixing member contained in the chamber; and (2) a control device comprising a second housing containing: (a) a detection system adapted to measure a property of a liquid at a prespecified first location in the chamber of the mixing cartridge, (b) means for holding the cartridge so as to register the chamber with the detection system, and (c) means for magnetically imparting linear reciprocal motion to the mixing member, whereby the mixing member sweeps out a portion but less than all of the volume of the chamber, the motion generally occurring at a second location in the chamber different from the first location. The mixing cartridge itself is also a part of the present invention.