Introduction

Your OT-2 moves pipettes around in 3D space. To do that accurately and precisely, it needs to be calibrated.

Calibration on the OT-2 happens in three parts: deck calibration, pipette calibration, and labware calibration. In this article, you'll learn more about what each part does, and how they all work together to move your pipettes to the right places.

Deck calibration

What does deck calibration do?

Deck calibration is the most fundamental part of calibration. It gives your OT-2 a basic notion of how to move pipettes around in 3D space.

Through deck calibration, your OT-2 learns how to translate spatial tasks, like moving a pipette 9 mm to the left, into low-level mechanical tasks, like rotating a motor clockwise by 30°.

How does deck calibration work?

Your OT-2's deck is precision-engraved with reference points. Deck calibration uses them to establish the OT-2's 3D coordinate system.

First, you show the OT-2 how high the deck is, by lowering a pipette until the tip just barely touches the surface. This affects the coordinate system's vertical offset.

Then, you move the tip to three crosses engraved near the deck's corners. This affects the coordinate system's rotation, skew, and lateral offset.

Your OT-2 uses the length of Opentrons tips in its calculations, so it is important to use Opentrons tips during deck calibration.

Why is deck calibration necessary?

Deck calibration compensates for manufacturing variation from robot to robot. It can also compensate for mechanical drift over long periods of time.

How do I do deck calibration?

See Get started: Calibrate the deck.

When do I have to do deck calibration?

  • As part of setting the OT-2 up for the first time.
  • After moving the OT-2 more than a short distance.
  • Once or twice per year, for maintenance.
  • When troubleshooting some movement and calibration issues.

Pipette calibration

What does pipette calibration do?

Pipette calibration is an adjustment on top of deck calibration. It determines:

  • An additional lateral adjustment for each pipette.
  • The length of tips.
  • The offset between pipettes.

How does pipette calibration work?

There are five tip probe switches hidden under the removable trash bin. To calibrate a pipette, the OT-2 slowly moves it towards each switch until the switch gets triggered. This lets the OT-2 automatically compute the pipette's lateral offset and tip length.

Why is pipette calibration necessary?

Pipette calibration automatically compensates for variation in how the pipettes are attached. Without it, you would have to do deck calibration every time you attach a new pipette.

How do I do pipette calibration?

You'll be prompted to calibrate pipettes before running a protocol. See Get started: Pipette and labware calibration.

Do I have to do pipette calibration every time?

See: Do I have to do pipette and labware calibration every time I upload a protocol?

Labware calibration

What does labware calibration do?

Labware calibration fine-tunes the position of labware.

How does labware calibration work?

For each labware, the OT-2 moves the pipette tip to where it thinks the top of well A1 is. Then, you make manual adjustments until the tip is perfectly centered. The OT-2 saves those adjustments for when it runs your protocol.

Why is labware calibration necessary?

Theoretically, since the OT-2 knows the labware's geometry and where each slot on the deck is, it should be able to perfectly predict the location of each well.

However, in reality, there can be slight variations in physical labware and how those labware fit into slots. Those slight variations do add up, and can cause the pipette tip to miss wells or crash. Labware calibration compensates for this.

How do I do labware calibration?

You'll be prompted to calibrate labware before running a protocol. See Get started: Pipette and labware calibration.

Do I have to do labware calibration every time?

See: Do I have to do pipette and labware calibration every time I upload a protocol?

What else should I know about labware calibration?

Labware calibration is shared across slots. If you calibrate labware in one slot, that calibration data is applied to all slots that that labware exists in. This will affect your protocol if you’re using multiple of the same labware.

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