188
Automated Dispensing
Liquid Handling Systems
Reagent
Slide/Plate
Wash
Tip
*DPR = Digital
System Fluid
Reservoir
Helium
Source
DPR
Microsolenoid
Valve
Hybrid
Valve
Syringe
Valve
Syringe
R
(reservoir
position)
T
(tip
position)
S
(syringe
position)
D
(dispense
position)
Pressure
Regulator
Air Gap
Dispensing
Technology inAction
High-speed photography of a typical dispense. Note the precise
initiation and termination of the dispense stream.
Rangeof ChemistriesDispensed
Third party precision results of a wide range of challenging reagents
10.0
12.0
14.0
8.0
6.0
4.0
2.0
0
0.05%
Brij
0.1%
Brij
0.5%
Brij
10%
DMSO
30%
DMSO
70%
DMSO
5%
BSA
10%
BSA
1%
Glycerol
30%
Glycerol
100 nL Dispenses
Application Note
High Precision Non-Contact Dispensing
From drug screening to crystallography, researchers seek to increase
throughput while lowering the use of costly or hard-to-produce samples
and reagents. Innovadyne’s approach to liquid handling—high-precision,
non-contact dispensing (based on advances in solenoid valves and fow path
technology)—offers a robust and low-maintenance means of achieving assay
volume reduction without compromising precision or accuracy. Precision
is improved at all points in the dynamic range (from 100 nanoliters to 500
microliters).
Limitations of Current Approaches
The limiting factor of traditional liquid handling techniques is the fact that
they rely on low energy displacement. To perform a reproducible and
accurate dispense, the last task of any pipetting action relies on a touch off.
Classical displacement techniques do not have enough energy to break the
surface tension of the last droplet. So a dragging action — touch off — is
employed, either against the solid surface of a vessel or a liquid surface.
Consequently, this technique is variable — it varies with liquid properties,
temperature, humidity, surface adhesion, and other factors. At larger volumes
the variation is small enough to have little impact on the end result. However,
when the total volume pipetted is small, this variation has a signifcant
negative impact on precision. The lower the volume, the larger is the
contribution of the variation.
Advantages of Non-Contact Dispensing
Non-contact liquid handling relies on the combined use of rapidly actuated
solenoid dispense valves, a controlled pressurized liquid source, and
fow path control via hybrid valves. The speed and energy of the fuid
displacement enables the surface tension of the liquid to break as it leaves
the orifce, eliminating the need for a touch-off.
The lack of a touch-off eliminates variability issues. The following bar graph
provides a typical example of the precision achieved with Innovadyne
dispensing instruments at 100 nL:
Another important beneft of non-contact dispensing is speed. The non-
contact technique allows the delivery nozzle to accurately deliver the droplet
above the target well, and to rapidly move to the next well. With the non-
contact technique, dispensing becomes independent of the plate type
or substrate, eliminating many of the reproducibility problems associated
with motion control. Plate processing times fall dramatically. Using non-
contact dispensing it is possible to deliver to all wells of a 96 well plate in
approximately 5 seconds, 384 wells in approximately 7 seconds, and 1536
wells in approximately 14 seconds.
5.0%
4.0%
3.0%
2.0%
1.0%
0.0%
1
2
3
4
AVG
Plate Number
3.70%
3.98%
4.29%
3.66%
4.09%
Plate CVs – Typical multiple plate precision performance at 100 nL
SimpleFlowPath Increases Reliability
Flow path – A schematic of the Innovadyne
™
flow path where no
sample or reagents come in contact with moving parts.
FOR ORDERING & DISTRIBUTOR INFORMATION +1 800 426 0191 • +1 360 679 2528 • www.idex-hs.com