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Electronic Micropipettes

Electronic Micropipette

Info

Discord forum thread.

Development information available here.

Overview

Our custom single-channel micropipette can dispense a wide range of volumes: 1000-100 microliters (p1000), 200-20 microliters (p200), and 20-2 microliters (p20) and 2.0-0.2 microliters (p2).

Thanks to its tip holder, there is no need to swap between different tools when switching between different tips for different volume ranges.

The micropipette is mounted to the structural frame on the "micropipette parking post". The robot's tool-changer can pick it up, move it around, and park it, just as a PhD student would (?).

This section provides instructions for building the Pipettin bot's micropipette, including drawings, manufacturing instructions, design notes and other options you may want to consider.

Expected results:

front back

Micropipette and its tool-plate.

TO-DO

Most of this guide still has content from the first version, which has been supersseded by version 2.

Usage

This micropipette is designed to be used by a robot and cannot be used manually with ease or precision. It is only intended for automated liquid-handling.

The tip-ejector mechanism is not a part of the micropipette itself. Instead, the tips are ejected against a post that is mounted on a 20x20 aluminum V profile.

imagen_2023-11-13_150148465.png tipejectorreal.jpg

Tip ejector

The tool parking post is a fixture that is attached to the 20x20 aluminum V profile, where the tools are parked. The tool changer can then grab the tools, move them accordingly, and park them again. The tool parking post is a convenient way to park the micropipette or any other tool when they are not in use.

Each tool, such as de micropipette, has its own tool-post (which is always attached to the tool) and its own parking post.

toolpafreecad.png toolpareal.jpg

Tool parking post

toolpark_toolplate.png toolpa_toolpost.jpg

Tool parking and tool-plate

The tip holder mechanism, can be 3D-printed in resin by SLA, or turned in a CNC lathe (with a few operations and tools).

supporev1.png

Tip holder with p1000 tip

tipssizes12.png

Tip holder with p20, p200 and p1000 tips.

Eliminating the need for tool switching across volume ranges, the Pipettin tip-holder speeds up workflows, avoiding the need for tool-changes. It accommodates dispensing from microliter scales (0.2 µL with a p2 tip) to larger volumes (1000 µL with a p1000 tip) using just one custom micropipette and its tip holder.

This replaces the traditional approach of juggling around multiple pipettes for different volume ranges, simplifying benchwork and enhancing efficiency.

It does not, however, have a tip ejector, which is why we need a tip ejector post.

Info

To learn more about Pipettin holder visit this page.

To learn more about 3D printing with resin and more visit this page.

Warning

The acetal/Delrin tip-holder is compatible with non-aggressive chemicals. Avoid using it with acids, bases, organic, volatile, or other corrosive substances.

Safety Precautions

This is an automatic micropipette, with a relatively strong linear actuator. Avoid putting your hands or fingers into it's mechanisms while it is active.

Avoid touching it with your bare hands when cleaning it, as it may be contaminated with the samples it handled.

Assembly

Versions

There are two main versions, differing in the seal they use:

  • PTFE seal (plus preload with 007 o-ring; ID: 6.07, CS: 1.78, OD: 9.525).
  • Just a metric 6x2 o-ring.

Here we show only the "plain" o-ring version, which has been tested to work. To learn more about these o-rings, read this.

Both use the same tip holder and Dowel pin.

TODO

Instructions to manufacture the PTFE seal are not finished.

Step 1: Gather parts

Parts and materials:

3D printed parts:

  • 1x PIP-SUP-CR.V1
  • 1x PIP-SUP-ST.V1
  • 1x PIP-SUP-LW.V1
  • 1x PIP-SUP-STEM.V1
  • 1x PIP-CPL-SHEAT.V1
  • 1x TRAP-RING-6MM.V1
  • 1x PIP-TRI-PLATE.V1
  • 1x PIP-RIGHT-SUPP.V1
  • 1x PIP-LEFT-SUPP.V1
  • 1x PIP-6D-SHEAT.V002

Of-the-shelf parts:

  • 12x M3 x 12 mm screws
  • 4x M3 x 16 mm screws
  • 2x M4 x 12 mm screws
  • 4x M4 x 30 mm screws
  • 6x M4 washers
  • 2x LMF8LUU bearings
  • 1x Antibacklash Nut
  • 2x 8mm Axis x 136mm
  • 1x Flexible coupling for motor
  • 1x POSITIONING PIN D6MM L50MM
  • 1x 6mm diametter o-ring
  • 1x T8 LEADSCREW.
  • 1x Neodymium magnet
  • 1x Stepper motor

Tools for assembly:

  • Alen wrenches and screwdrivers, sizes M3, M4, and M5.

Step 2: Assemble the tip ejector

Follow the ejection post assembly guide.

alt text

Step 3: Assemble the micropipette

  1. First of all you need to attatch the CPL-ST piece to the stepper motor and the T8 LEADSCREW with four M4 screws

imagen_2023-12-27_144656384.png

  1. Attach the PIP-SUP-ST piece to the stepper with four M3 x 16cm screws (red)

imagen_2023-12-27_143344824.png

  1. Add the two 8mm axis at the side holes of the PIP-SUP-ST and attatch them with two M4 screws for each axis.

imagen_2023-12-27_144825399.png

  1. Put the two LMF8LUU bearings into the side holes of the PIP-SUP-CR and secure each one with four M3 x 12cm screws

imagen_2023-12-27_134501545.png

  1. On the central hole of the PIP-SUP-CR you need to put the M8-AB-NUT (its an antibacklash nut) with four M3 x 12cm screws

imagen_2023-12-27_141755411.png

Note

Now you have two assemblies, the two firts steps are for the ASS-PIP-ST and the third and fourd steps are for the AS-PIP-CARR.

  1. Join the assemblies, aligning the two 8mm axis to the holes of the LMF8LUU bearings, and the M8 LEADSCREW with the antibacjlash nut

imagen_2023-12-27_145005523.png

  1. Now you can put the AB-SPRING and the other part of the antibacklash system (M8-AB-TOP)

imagen_2023-12-27_145222822.png

  1. Add to the neodymium magnet and the M6-CAP-SCREW to the top of the PIP-SUP-STEM piece

imagen_2023-12-27_152247439.png

  1. Attach the PIP-SUP-STEM with two M4 x 12 mm screws and two M4 washers (grey) on each side of the PIP-SUP-CR

imagen_2023-12-27_152725589.png

  1. Now you need to put the 6D-O-RING (Blue), the TRAP-RING (Red) and the TRAP-SPRING (Grey) into the hole of the PIP-6D-SHEAT (Yellow)

imagen_2023-12-27_155232173.png

  1. Then, you can put the PIP-6D-SHEAT into the PIP-CPL-SHEAT piece

imagen_2023-12-27_155418824.png

  1. Attatch the PIP-CPL-SHEAT to the PIP-SUP-LW with four M4 x 30mm screws and four M4 washers (Grey)

imagen_2023-12-27_155609728.png

  1. Join the PIP-SUP-LW piece to the previous assemblies, aligning the M8 axis to the side holles of the 3D piece

imagen_2023-12-27_160017471.png

  1. Before finishing, you must attach the PIP-RIGHT-SUPP and PIP-LEFT-SUPP pieces to the sides of the PIP-TRI-PLATE piece with two M3 screws and nuts each

imagen_2023-12-27_160349483.png

  1. Finally you can join the PIP-TRI-PLATE to the PIP-SUP-LW with four M5 screws (Red arrows)

imagen_2023-12-27_160703951.png

Installation

Warning

Not yet documented. Punteo para escribir:

  • Montaje del parking post sobre el marco del robot.
  • Agregado de partes para tool-changing (agujeros para el parking post, y placa/llave para toolchanger).
  • Protocolo de calibración (gravimétrica). (NO ESCRIBIR)
  • Montaje sin tool-changer, directo al perfil 2040 del eje Z.

Interactions

Pipettin bots micropipette tool interacts with the rest of the robot through the PIP-TRI-PLATE (green), which is attached to the HEAD_PLATE (pink) piece belonging to the toolchanger system.

The latter, in addition to being part of the toolchanger system, is also attached to the 20x40 V profile of the Z-axis of the Motion System.

imagen_2023-12-29_164338629.png imagen_2023-12-29_164303414.png

It also interacts with the Tool Parking system through the two pieces PIP-RIGHT-SUPP and PIP-LEFT-SUPP (green), which are designed to rest on the hex cap screws (red) attached to the PIP-PARK-HOLDER piece belonging to the Tool Parking system

imagen_2023-12-29_164847531.png

The PIP-6D-SHEAT.V1 piece interacts with the tip ejector and the racks. The tip ejector, as its name suggests, is responsible for ejecting the used tips.

Subsequently, in both the tube racks and tip racks, it manages to retrieve liquid from the tubes and also grab the tips.

Maintenance

Punteo para escribir:

  • Cada cuanto calibrar de nuevo. Protocolo corto de calibración gravimétrica (3 volumenes, 3 puntos, etc.).

The general considerations for the maintenance of the pipette are the following:

  1. It is necessary to check periodically that the screws and nuts are properly tightened, as the vibration and movements of the machine can cause a slight misalignment over time and with the use it receives.

  2. The pipette axes must be well lubricated for its proper movement. This lubrication can be performed every few months, depending on the amount of use the machine receives.

  3. Ensure that no chemicals come into contact with the PLA material used for 3D printing, as it may be damaged.

Seal maintenance

The guidelines for the maintenance for the O-ring are:

  1. Clean the O-ring surfaces and pipette components regularly to remove any residue or contaminants that may compromise the seal. Use mild solvents or cleaning solutions compatible with the pipette materials.

  2. Conduct periodic visual inspections of the O-ring for signs of wear, cracks, or any damage. If any issues are detected, promptly replace the O-ring to maintain a reliable seal.

  3. If the O-ring exhibits significant wear, loss of elasticity, or any other issues, replace it promptly. Worn O-rings can compromise the seal and affect pipette accuracy.

Tip holder maintenance

Regular maintenance of a resin tip holder depends on factors such as usage frequency, the type of resin used, and environmental conditions. You must consider the following guidelines:

  1. Clean the tip holder regularly to remove any residue, dust, or contaminants. Use a soft cloth or a swab dampened with a mild cleaner.

  2. Periodically inspect the resin tip holder for cracks, wear, or any signs of deterioration. If issues are found, consider repairing or replacing the tip holder.

  3. Avoid exposing the tip holder to harsh chemicals that may damage the resin. If contact with chemicals occurs, clean it immediately and check for any damage.

  4. Store the tip holder in a clean, dry place when not in use. Avoid extreme temperature or humidity conditions that could affect the integrity of the resin.

  5. Protect the tip holder from impacts or falls that may cause damage. Depending on the type of resin, it may be susceptible to breakage or chipping upon impact.

  6. If you notice significant deterioration in the resin of the tip holder, consider repairing or replacing it to maintain optimal performance.

Design

Punteo para escribir:

Previous versions

There is an older but almost identical version of the pipette, originally designed by Bruno and ported to FreeCAD by Agustín.

It was re-designed for compactness, and to reuse the carriage design from the pipette adapter tool.

imagemicrop.png

microrealactualizada.png

Models

The latest versions of all files will be available at this link.

  • CPL-ST: custom part
  • Material: PLA
  • CAD: CPL-ST.FCStd

  • Part number: CPL-ST

  • ROD-LMF8LUU: custom part

  • Material: PLA
  • CAD: ROD-LMF8LUU.FCStd

  • Part number: ROD-LMF8LUU

  • M8-AB-NUT: custom part

  • Material: PLA
  • CAD: M8-AB-NUT.FCStd

  • Part number: M8-AB-NUT

  • AB-SPRING: custom part

  • Material: PLA
  • CAD: AB-SPRING.FCStd

  • Part number: AB-SPRING

  • M8-AB-TOP: custom part

  • Material: PLA
  • CAD: M8-AB-TOP.FCStd

  • Part number: M8-AB-TOP

  • O-RING-SEAT: custom part

  • Material: PLA
  • CAD: O-RING-SEAT.V1.FCStd

  • Part number: O-RING-SEAT.V1

  • M6-CAP-SCREW: custom part

  • Material: PLA
  • CAD: M6-CAP-SCREW.FCStd

  • Part number: M6-CAP-SCREW

  • 6D-O-RING: custom part

  • Material: PLA
  • CAD: 6D-O-RING.FCStd

  • Part number: 6D-O-RING

  • 7D-O-RING: custom part

  • Material: PLA
  • CAD: 7D-O-RING.FCStd

  • Part number: 7D-O-RING

  • PIP-6D-SHEAT: custom part

  • Material: PLA
  • CAD: PIP-6D-SHEAT.V1.FCStd

  • Part number: PIP-6D-SHEAT.V1

  • PIP-7D-SHEAT: custom part

  • Material: PLA
  • CAD: PIP-7D-SHEAT.V1.FCStd

  • Part number: PIP-7D-SHEAT.V1

  • PIP-CPL-SHEAT: custom part

  • Material: PLA
  • CAD: PIP-CPL-SHEAT.V1.FCStd

  • Part number: PIP-CPL-SHEAT.V1

  • PIP-SUP-LW: custom part

  • Material: PLA
  • CAD: PIP-SUP-LW.V1.FCStd

  • Part number: PIP-SUP-LW.V1

  • 8MM-AXIS: custom part

  • Material: PLA
  • CAD: 8MM-AXIS.FCStd

  • Part number: 8MM-AXIS

  • PIP-SUP-ST: custom part

  • Material: PLA
  • CAD: PIP-SUP-ST.V1.FCStd

  • Part number: PIP-SUP-ST.V1

  • TRAP-SPRING: custom part

  • Material: PLA

  • Part number:TRAP-SPRIN

  • TRAP-RING-6MM: custom part

  • Material: PLA
  • CAD: TRAP-RING-6MM.V1.FCStd

  • Part number: TRAP-RING-6MM.V1

  • PIP-ENDSTOP-SUP: custom part

  • Material: PLA
  • CAD: PIP-ENDSTOP-SUP.V1.FCStd

  • Part number: PIP-ENDSTOP-SUP.V1

  • PIP-TIPS-EJECTOR: custom part

  • Material: PLA
  • CAD: PIP-TIPS-EJECTOR.V1.FCStd

  • Part number: PIP-TIPS-EJECTOR.V1

  • PIP-SUP-STEM: custom part

  • Material: PLA
  • CAD: PIP-SUP-STEM.V1.FCStd

  • Part number: PIP-SUP-STEM.V1

  • PIP-SUP-CR: custom part

  • Material: PLA
  • CAD: PIP-SUP-CR.V1.FCStd

  • Part number: PIP-SUP-CR.V1

  • PIP-TRI-PLATE: custom part

  • Material: PLA
  • CAD: PIP-TRI-PLATE.V1.FCStd

  • Part number: PIP-TRI-PLATE.V1

  • THSL-NUT-8X4: custom part

  • Material: PLA
  • CAD: THSL-NUT-8X4.FCStd

  • Part number: THSL-NUT-8X4

  • PIP-SIDE-SUPP: custom part

  • Material: PLA
  • CAD: PIP-SIDE-SUPP.V1.FCStd

  • Part number: PIP-SIDE-SUPP.V1

  • 12x M3 x 12 mm screws: off-the-shelf parts.

  • 4x M3 x 16 mm screws: off-the-shelf parts.
  • 2x M4 x 12 mm screws: off-the-shelf parts.
  • 4x M4 x 30 mm screws: off-the-shelf parts.
  • 6x M4 washers: off-the-shelf parts.
  • 2x LMF8LUU bearings: off-the-shelf parts.
  • 1x Antibacklash Nut: off-the-shelf parts.
  • 2x 8mm Axis x 136mm: off-the-shelf parts.
  • 1x Flexible coupling for motor: off-the-shelf parts.
  • 1x POSITIONING PIN D6MM L50MM: off-the-shelf parts.
  • 1x 6mm diametter o-ring: off-the-shelf parts.
  • 1x T8 LEADSCREW: off-the-shelf parts.
  • 1x Neodymium magnet: off-the-shelf parts.
  • 1x Stepper motor: off-the-shelf parts.

Software

Warning

Documentation not yet available.

Development

These 3D-printed parts were designed in FreeCAD 2.1 and 2.0, then exported in the FCStd format for slicing. They were printed on an Original Prusa i3 MK3 using STL files.

If you want to dive into file formats visit here.