In order for the OT-2 robot to interact with any given labware, the robot needs to reference a corresponding JSON definition file which contains the accurate measurements of that labware. This list of measurements informs the robot about the type and shape of the labware.
Your OT-2 comes pre-loaded with a set of Opentrons and 3rd party labware definitions. The full list of these standard labware can be found in the Opentrons Labware Library. To include these labware in your protocols, simply browse for them in Protocol Designer or import them by name into your Python API protocols (read more here).
Once you have a labware definition, we recommend you calibrate it for use on the OT-2. Calibration does not modify the labware definition, it only adjusts its position in relation to the deck of the robot. While calibration can be used to compensate for small differences between the height of the labware and the labware definition, we generally recommend using an exact labware definition to match your specific labware.
The following is the full list of data in a labware definition JSON file, which describes both its dimensions and properties such as manufacturer and labware category.
Count- The total number of tubes or wells in your labware.
Max volume (uL)- Total maximum volume of each well/tube/tip.
Shape- The shape of the bottom of a well or tube.
Length (mm)- When you look top down at your labware while on the robot’s deck there should be a long and short side. Length is the long side.
Width (mm)- When you look top down at your labware while on the robot’s deck there should be a long and short side. Width is the short side.
Height (mm)- The distance between the top of a tube/well (include any lip but exclude any cap) to the bottom of a labware.
Depth (mm)- The distance from the top of the well/tube (include any lip but exclude any cap) to the bottom of the inside of a well/tube.
Total length (mm)- The distance from the top of the tip to the bottom of the tip.
Diameter (mm)- The inner diameter of a circular well, tube, or tip.
X-size (mm)- The length of the x side of a rectangular well.
Y-size (mm)- The length of the y side of a rectangular well.
X-spacing (mm)- The spacing between columns, measured from the center of a well/tube/tips.
Y-spacing (mm)- The spacing between rows, measured from the center of a well/tube/tips.
X-offset (mm)- The distance from the center of well/tip/tube A1 to the left edge of the labware.
Y-offset (mm)- The distance from the center of well/tip/tube A1 to the top edge of the labware.
Sometimes you will need to stack labware on top of a second piece of labware to use it on the OT-2. Examples of this are when you use the Opentrons tube racks and Opentrons aluminum blocks with tubes or plates.
In these instances, you will require only one labware definition to represent the stacked labware. For that reason if you want to calibrate the labware or obtain a height measurement, you must stack the labware first.
Please note that each tube/plate variation used in conjunction with a tube rack or aluminum block will require its own unique definition to ensure accurate pipetting.