Liquid Class Properties

Opentrons-verified liquid classes are based on the properties of common liquids: water, ethanol, and glycerol.

Opentrons-verified liquid class Description Load name
Aqueous Based on deionized water water
Volatile Based on 80% ethanol ethanol_80
Viscous Based on 50% glycerol glycerol_50

Use Opentrons-verified liquid classes in your transfers to automatically apply optimized behavior. For example, choosing the glycerol_50 liquid class changes properties, like flow rate, to accurately transfer viscous liquid.

Other propreties like submerge speed, touch tip, and air gap can help prevent splashing or dripping of a volatile liquid, or reduce air bubbles forming in a viscous liquid.

Each Opentrons-verified liquid class is defined by a set of these properties:

Property Description

Submerge position

 The pipette begins at this position above the liquid.

Submerge speed

 The pipette submerges into the liquid at this speed.

Delay after submerging

The pipette delays a specified amount of time:

  • before submerging into or retracting from liquid.
  • before or after an aspirate or dispense.
  • after a push out.

Mix liquid

 The pipette mixes liquid inside the well before an aspirate or after a dispense.

Pre-wet tip

 The pipette pre-wets the attached tip before aspirating liquid.

Aspirate flow rate
  • The pipette aspirates liquid at this speed.
  • Varies by volume.

Dispense flow rate
  • The pipette dispenses liquid at this speed.
  • Varies by volume.

Retract position

 The pipette retracts from the liquid and moves to this position.

Retract speed

 The pipette retracts from the liquid at the specified speed.

Push out
  • The pipette dispenses a small amount of air to ensure all liquid leaves the tip.
  • Varies by volume.

Touch tip

 The pipette touches the attached tip to the sides of a well to remove droplets.

Air gap
  • The pipette aspirates a small amount of air after an aspirate or dispense.
  • Varies by volume.

Blow out

 The pipette dispenses a larger amount of air to ensure all liquid leaves the tip.

A liquid class definition specifies values for each property. When your Flex protocol includes a liquid class, these property values automatically define transfer behavior. For example, if you use the transfer_with_liquid_class() command to transfer a viscous liquid, the pipette submerges into the liquid and aspirates more slowly to prevent air bubbles from forming.

Read more about using liquid classes in the next section.