Chapter 3
System description
3.2.6 Washer
The reaction modules are washed in the washing system (washer)
where excess reaction compound is aspirated. Three independently
controlled injection pumps administer the wash liquid to three
separate dispensing (injection) probes. All pumps operate with a
constant volume of 400 µl.
The three aspiration (suction) probes (located beside the dispensing
probes) are connected to separate tubes, but all function from one
common suction pump. If no reaction module or an empty one is
under the aspiration probe, only air is aspirated.
During transport of the reaction modules in the washer, the probes
are automatically lifted and lowered again for suction. Suction and
lowering are synchronized to limit immersion and contamination of the
probes. All dispensation and aspiration probes are mounted on a
common lifting carriage (Washer lift).
The four height positions of the probes are:
1. Transport position
In this position, the suction needles are lifted only enough to
allow free movement of the reaction module in the washer
channel (one step to the next position).
2. Injection position:
In this position, the injection needles are dipped just below the
surface of the reaction module where wash liquid is then dispensed.
3. Suction position:
In this position, the suction needles drop slowly to touch the base of
the reaction modules while constantly aspirating.
4. Priming position:
In this position, the suction needles are located in the recesses
(priming wells) of the washer transport channel where constant
dispensing and aspiration take place simultaneously.
Page 3-16
Operating instructions