Cartridges and uses thereof

A diagnostic test instrument comprising:

• a base comprising a first channel configured to receive a fluid, the fluid including a test sample to be tested on the diagnostic test instrument;
• a structure comprising a second channel, the structure being configured to move relative to the base between a first position and a second position;
• wherein, in the first position, the first channel and the second channel are aligned to create a fluidic connection between the first channel and the second channel and, in the second position, the first channel and the second channel are unaligned to block a fluidic connection between the first channel and the second channel;
• and
• a reservoir for receiving the test sample, at least some of the test sample comprising a first part of the fluid;
• wherein the first channel comprises a first section and a second section, the first section being fluidically connected to the reservoir;
• and
• wherein, in the first position, the second channel is between the first section and the second section of the first channel to create the fluidic connection to enable the second section of the first channel to receive the first part of the fluid from the first section of the first channel.