AM Dispense task parameters

About this topic

This topic describes the task parameters for the AM Dispense task, which is available only for the Bravo 96AM Head.

The AM Dispense task is designed for dispensing fluids through AssayMAP Bravo cartridges that are mounted on the Bravo 96AM Head. In addition to the parameters for the Dispense task, the AM Dispense task allows you to override the flow rate from liquid class.

To run the AM Dispense task from Diagnostics, see Performing a task using Bravo Diagnostics. To use the task in a protocol, see the VWorks Automation Control User Guide.

Parameter description

The AM Dispense task has the following parameters.

 

 

 

Parameter	Description
Empty tips	The option to empty all liquid from the probes, cartridges, or tips instead of using the dispense volume specification.
Volume (µL)	The volume of liquid to be dispensed from each probe, cartridge, or tip.
Blowout volume (µL)	Specifies the volume of air to dispense after the main volume has been dispensed while the probes, cartridges, or tips are still in the wells. Typically, the blowout volume is the same as the pre-aspirate volume. Note: Blowout occurs only in the last quadrant dispensed for a given AM Dispense task.
Liquid class	The pipetting speed and accuracy. IMPORTANT To ensure consistent pipetting, always select a liquid class for liquid-handling tasks.
Override dispense flow rate from liquid class	The option to override the dispense velocity in the selected liquid class. Selecting this option enables you to specify a value for the dispense flow rate without changing the liquid class.
Dispense flow rate (0–500 µL/s)	The numerical value or the JavaScript variable that will override the dispense velocity setting in the liquid class. A JavaScript variable enables the value to be assigned later. For example, using a VWorks form, an operator could easily change the flow rate for an aspirate step in increments from as low as 1 µL/min up to 2000 µL/min or more using the same liquid class. If the task is included in a VWorks macro, a JavaScript variable enables you to change the value for the task at the macro level. IMPORTANT The software requires that the flow rate value be in microliters per second (µL/s) at run time. If you want an operator to enter the value in microliters per minute (µL/min), you can use scripting to convert the values for the software to use.
Distance from well bottom (-20–100 mm)	The distance between the tips of the probes, cartridges, or disposable tips and the well bottoms during the AM Dispense task. If you specify dynamic tip extension, this is the distance at the end of the AM Dispense task. Use a positive number for tasks that are performed with mounted cartridges, mounted tips, or bare probes at labware other than a cartridge rack. If the task is performed in the upper cup of unmounted cartridges, you can use a negative number for the parameter value. In this case, the well bottom is the top of the cartridge cup, as shown in the following figure. For example, a negative number enables a prewetting step before mounting and priming the cartridges. IMPORTANT You can use a negative number for this parameter only if the AM Dispense task is performed in cartridges that are located in a cartridge rack. IMPORTANT The labware definition must be accurate and the teachpoint must be precise in order for the system to position the tips at the correct distance from the well bottom.
Dynamic tip retraction (0–20 mm/µL)	The rate at which to raise the pipette head during the Dispense task. Use dynamic tip retraction to prevent spills as the pipette tips displace the liquid. To move the tips: • At the same rate as the volume change. Calculate dynamic tip retraction (DTR) as follows: DTR = (well depth)/(well vol) = 1/A, where A is the cross-sectional area of a well with straight walls • Faster than the volume change. DTR > 1/A • Slower than the volume change. DTR < 1/A The starting and ending positions can be calculated as follows: (Vdispensed * DTR) + Distancewell bottom
Pipette technique	The pipette location offset you want to use for the AM Dispense task. The list of pipette techniques are defined in the Pipette Technique Editor.
Perform tip touch	The option to touch the probes, cartridges, or tips on one or more sides of the well.
Which sides to use for tip touch	The side or sides of the well to use during tip touch: North, South, East, West, North/South, West/East, West/East/South/North.
Tip touch retract distance (–20 to 50 mm)	The vertical distance for the probes, cartridges, or tips to rise before touching the sides of the wells.
Tip touch horizontal offset (–5 to 5 mm)	The horizontal distance the tips move. The value is based on the well diameter specified by the labware definition. For example, if you set a value of: • 0, the tips move a horizontal distance equal to the well radius • > 0, the tips attempt to move past the well radius, which results in a more forceful tip touch • < 0, the tips move a distance less than the radius of the well, resulting in a lighter tip touch

 

 

Related information

 

For information about…	See…
Opening Diagnostics	Opening Bravo Diagnostics
Editing the labware classes, liquid library, or pipetting techniques	VWorks Automation Control Setup Guide
Performing a diagnostic task	Performing a task using Bravo Diagnostics
Reporting a problem	Reporting problems