Immunosensor

A disposable device for use in detecting a target antigen in a fluid sample having a pH, the device comprising a reaction chamber having an internal surface, a proximal end, and a distal end;

• an immobilized antibody that binds to the target antigen fixed within the reaction chamber;
• a reporter complex present within the reaction chamber, the complex comprising a probe, wherein the reporter complex mixes with the sample in the reaction chamber;
• a detection chamber having a wall, an internal surface, a distal end and a proximal end, the detection chamber being initially configures in a first, unvented, state and further being configured to permit modification to a second, vented, state during use;
• a sample ingress at the distal end of the reaction chamber;
• and a sample passageway between the distal end of the reaction chamber and the proximal end of the detection chamber, the passageway having dimensions selected to block free flow of fluid from the reaction chamber to the detection chamber when the detection chamber is unvented, while permitting free flow of fluid from the reaction chamber to the detection chamber when the detection chamber is vented.