Tandem Pump
Dispensing
A syringe pump operates by first
filling the syringe using a fill line connected to a reagent reservoir
and then it can switch the outlet connection on the syringe to a second
line and reverse the direction of the syringe plunger and displace the
fluid through the second line to dispense the reagent using a
programmed displacement. The problem is that once the dispensed fluid
equals the original fill volume of the syringe the syringe must be
refilled by switching the syringe valve to the fill position. At this
point the dispensing operation must cease to allow the syringe to
refill and then switching back to the dispensing position. In
dispensing operations where continuous dispensing such as dispensing on
a continuous moving web a single syringe pump will not work. The
solution to this problem is to use two syringe pumps for a single
dispense operation where the syringes alternately fill and dispense to
provide continuous flow for the dispensing operation. This
configuration is denoted as a “Tandem Pump”. This
allows the use of small high resolution syringes in the range of 250
μL to be used. With this configuration continuous dispensing can
be achieved with no limitations of the web length.
BioDot uses the “Tandem
Pump” configuration for bulk dispensing on web based systems
for both drop as well as continuous lines. There are three
configurations of dispensers that use the Tandem configuration, Front
Lines, AirJet Quanti and the BioJet Quanti.
Front Lines
This configuration has a flexible dispense tip that rides on the
substrate surface with the dispensed fluid emerging from dragging tip.
The fluid flow rate can be synchronized with motion to create a
quantitative rate of flow per unit length of reagent on the substrate
surface.
AirJet Quanti
This configuration uses an aerosol type of dispense nozzle that using
pressurized air to atomize the fluid passing through the nozzle. This
creates a quantitative spray format where a dot or line can be
quantitatively generation on a continuous basis.
BioJet Quanti
This configuration uses a solenoid nozzle that is synchronized with a
positive displacement of the syringe to dispense drops at frequencies
in the range of 20-1000 Hz to dispense non-contact drops on a
continuous base.
Advantages:
1. Provides the ability to combine positive displacement dispensing
with continuous operation.
2. It can be configured to work with a range of different dispensing
methods.
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lines on
membranes
and other substrates for BioChips. The technology couples a high
resolution syringe pump with a microtube. During dispensing
the micro-tube glides across the surface of the membrane or
substrate to create a quantitative line. The width of the line can be
adjusted by increasing or decreasing the programmed volume of the line.
Using the Parallel
Synthesis
Silicon Pins allows for a very dense array with reduced carryover. The
Silicon Pins are also capable to aspirate from a 1536 well source plate
and have no pre-spotting requirements.
