Analytik Jena CyBio Well vario OL3381-25-300, Operating Manual

Page: 117 / 164

CyBio
®
Well vario Release: 2017 101
Operation
7.4 Specific System Details (Pipetting Head)
Aspiration and dispensing of liquid is accomplished by piston motion. All piston suspen-
sion points have a mechanical freeplay (slackness). This means: After each reversal in
piston motion direction, the piston drive initially covers a certain travel length without
actually moving the pistons, and, hence, without aspirating or dispensing any liquid.
This motion length corresponds to the freeplay.
In order to prevent dosing errors, a volume cycle is organized in such a way that the pis-
ton reversal point lies outside of the actual pipetting range (motion into zero-position,
aspiration with additional stroke) or is corrected by suitable compensatory motion (dis-
pensing with additional stroke).
7.4.1 Aspiration with Additional Stroke
Fig. 113: Aspiration with additional stroke
This is the recommended standard procedure for precise pipetting.
Piston motion starts in zero-position (1) and continues beyond the position that corre-
sponds to nominal pipetting volume. The pistons are then lowered back into this posi-
tion (2). The amount of freeplay (3) is excluded by this procedure. At the time of
1 Zero-position
2 Aspirate volume with
additional stroke and reverse
piston direction
3 Upper freeplay
4 Exactly dispense volume (single
volume or partial volumes)
5 Residual ejection
6 Move to zero-position
A1 = D2: nominal pipetting volume
A2: additional aspiration volume
D1: additional volume being dispensed
< A2 (additional stroke)
D2: nominal pipetting volume
D3: residual volume (proportional to
freeplay)
D4: air