Sample processing assembly for treatment of a sample on a substrate

A substrate retaining mechanism for use with a sample processing assembly for treatment of a sample on a substrate, wherein the assembly includes:

• a mounting block including a mounting surface for the substrate;
• a closure body configured to support a cover member, the closure body being rotatable about a first pivot axis between an open position and a closed position, such that when the substrate is placed in the assembly and the closure body is in the closed position, the cover member engages the substrate to form a reaction chamber for processing the sample;
• and a closure body arm rotatable about the second pivot axis and engaging with the closure body so that rotation of the arm about the second pivot axis causes movement of the closure body between the open and closed positions,
• the substrate retaining mechanism including:
• a cam, and
• a substrate retaining arm rotatable about the first pivot axis, the substrate retaining arm including a cam follower for sliding engagement with the cam,
• wherein the substrate retaining mechanism is configured so that
• when the closure body is closed and the cover member engages the substrate, the substrate retaining arm is clear of the substrate,
• as the closure body arm commences rotation to enable the closure body to rotate towards the open position, but whilst the closure body remains in a closed position, the substrate retaining arm moves into engagement with the substrate, and
• once the cover member is fully separated from substrate, the substrate retaining arm disengages with the substrate.