A capsule system comprising a first capsule (16) configured to be ingested by a subject, a second capsule (18) configured to be ingested by the subject separately from the first capsule, the first capsule having an electromagnetic element (29, 30) and a sensor (22, 23) for sensing a physiological parameter of a gastrointestinal tract of the subject, the second capsule having a magnetic element (29, 30) and a sensor (22, 23) for sensing a physiological parameter of the gastrointestinal tract of the subject, the first capsule and the second capsule having an active state wherein a magnetic force is selectively provided between the first and second capsules attracting the first and second capsules while the capsules are within the gastrointestinal tract of the subject and having an inactive state wherein the magnetic force is absent, and a control (26/32) configured to selectively place the capsules in the active state from the inactive state while the capsules are within the gastrointestinal tract of the subject.
