Instrument for performing a diagnostic test on a fluidic cartridge

A method of using a cartridge reader to actuate an isolation valve in a fluidic cartridge inserted into the cartridge reader, wherein the cartridge reader comprises a fixed upper clamp, and a lower clamp movable relative to the upper clamp, defining a cartridge receiving region therebetween, a gantry that is fixed relative to the lower clamp by at least one alignment shaft passing through at least one aperture in the upper clamp, an electromagnet mounted on the gantry and configured to align with and selectively engage an armature of an actuation assembly comprised in the lower clamp, wherein the actuation assembly further comprises an actuation member, and a first biasing means disposed between the actuation member and a bearing surface in the upper clamp, wherein the first biasing means is configured to bias the actuation member into a first position in which it actuates a mechanical valve in a fluidic cartridge inserted into the cartridge reader, and wherein the method comprises the steps of:

• a. moving the lower clamp from a first position in which the electromagnet is spaced apart from the armature, to a second position in which the electromagnet contacts the armature;
• b. activating the electromagnet, thereby magnetically engaging the electromagnet with the armature;
• c. moving the lower clamp from the second position to the first position, thereby compressing the first biasing means between the bearing surface and the actuation member;
• d. inserting a cartridge having an isolation valve into the cartridge reader between the upper and lower clamps;
• e. moving the lower clamp to a third position, thereby moving the cartridge from a first position in which it is spaced apart from the upper clamp, to a second position in which it engages the upper clamp;
• and
• f. deactivating the electromagnet, thereby releasing the actuation assembly and allowing the first biasing means to move the actuation member from a first position in which it does not actuate the isolation valve to a second position in which it actuates the isolation valve.