Method and apparatus for controlling reactions

An analytical device for controlling reactions, comprising:

• a housing enclosure defining an assay chamber and a fluid discharge port positioned radially outward from the assay chamber and in fluid communication with the assay chamber, the housing enclosure adapted for rotation about an axis;
• an active surface in the chamber which is not attached to the chamber;
• means for introducing fluid into the assay chamber;
• and
• a centrifugally-operated valve in fluid communication with the fluid discharge port, the valve repetitively operable between a stationary position and an actuated position, the valve operative to transition from the stationary position to the actuated position when a centrifugal force generated by rotating the housing enclosure exceeds a predetermined limit, and to transition from the actuated position to the stationary position when the centrifugal force does not exceed the predetermined limit, wherein said centrifugally-operated valve includes an actuator and a bias means that exerts a counteracting force to hold said actuator in a stationary position.

An analytical device for controlling reactions, comprising:

• a housing enclosure defining an assay chamber and a fluid discharge port positioned radially outward from the assay chamber and in fluid communication with the assay chamber, the housing enclosure adapted for rotation about an axis;
• an active surface in the chamber which is attached to the chamber;
• means for introducing fluid into the assay chamber;
• and
• a centrifugally-operated valve in fluid communication with the fluid discharge port, the valve repetitively operable between a stationary position and an actuated position, the valve operative to transition from the stationary position to the actuated position when a centrifugal force generated by rotating the housing enclosure exceeds a predetermined limit, and to transition from the actuated position to the stationary position when the centrifugal force does not exceed the predetermined limit, wherein said centrifugally-operated valve includes an actuator and a bias means that exerts a counteracting force to hold said actuator in a stationary position.