Magnetic Wash General Information

Overview

The Magnetic Wash module consists of a plastic MTUMulti-tube unit—Container used to process tests in the instrument. An MTU contains five separate reaction tubes. The MTU is moved through the instrument by the linear distributor and includes five tiplets for pipettiing to be used in the mag wash station. carriage that holds MTUs, a set of five dual fluid injectors that dispense oil and wash solution into the MTU tubes, a set of five aspirators designed to pick the MTU tiplets and aspirate fluid from the MTU tubes, and a magnet carriage that holds magnets intended to pull the ferrite beads to the side of the tubes. the MTU carriage moves the MTU to the proper position to pick tiplets and dispense oil and wash solution. The MTU carriage also doubles as an orbital mixer. The aspirators are moved up and down via a lead-screw. Aspirators are connected to a capacitance sensor which acts both as a liquid level sensor and as a tiplet presence sensor. The magnet carriage is engaged with the MTU via a drive-belt and also acts as the tip-stripping mechanism.

Interfacing Modules

The Magnetic Wash module interfaces with the Distributor by accepting MTUs from it. Timing with the Distributor is crucial, as the MTU must be removed before tiplets are stripped from the aspirator and the magnet wash module must finish stripping tips before the next MTU is introduced. the module also is directly connected to the liquid waste vacuum system and is mounted directly above the solid waste bin, where tiplets are dropped.

Theory/Sequence of Operation

The Distributor places an MTU into the Magnetic Wash module. The MTU carriage rotates the MTU into position to pick tips. The aspirators then descend to pick tiplets and a process control check is then performed to make sure the tiplets were picked. The magnets deploy and dwell for a period of time determined by the assay. Afterwards, the aspirators descend and aspirate the fluid in the MTU tubes. The wash routine then starts. The MTU carriage rotates into position underneath the injectors, wash solution is dispensed into the tubes, and the MTU carriage then mixes for 10 seconds (as determined by the assay). The magnets deploy and dwell before the wash solution is aspirated. For APTIMA Assays, the wash routine is performed two times consecutively. After the second wash routine, oil is dispensed into the MTU tubes. The Distributor then removes the MTU. A check for the presence of tiplets is performed, the tiplets are stripped from the aspirators, and another check is performed to confirm the absence of tiplets.