Assay device employing fluorescent labels

An assay device comprising:

• a housing;
• and
• a test portion, electronic circuitry and an optical assembly, each a least partially located in the housing;
• wherein:
• the test portion comprises at least one test zone;
• the electronic circuitry comprises at least one light source and at least one light detector;
• and
• the optical assembly comprises at least one light guide adapted to guide light from the at least one light source to the at least one test zone;
• wherein the at least one light guide comprises a first end and a second end opposite to the first end, and the at least one light guide further comprises:
• a convex light collimator lens provided at a first end face, the first end face being located at the first end of the at least one light guide and comprising a first edge and a second edge opposite to the first edge;
• and
• a light focussing reflector face and a light exit face, the light focussing reflector face joined to the first edge of the first end face and extending from the first edge towards the second end of the at least one light guide, and the light exit face joined to the second edge of the first end face and extending from the second edge towards the second end of the at least one light guide, the light focussing reflector face and the light exit face converging towards each other as they extend towards the second end of the at least one light guide,
• wherein the at least one light guide is configured such that at least a portion of light from the at least one light source enters the at least one light guide through the collimator lens, reflects off the light focussing reflector face and exits the at least one light guide through the light exit face to travel to the test zone,
• wherein the at least one light detector is configured to receive light emanating from the at least one test zone.