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eVOLVER
  • eVOLVER Documentation Wiki
  • General
    • About Us
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      • Code of Conduct
  • Getting Started
    • Buying eVOLVER
    • Part Sourcing
    • Unboxing and Setting Up
    • Software Installation
      • DPU Installation
      • Electron App (GUI) Installation
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      • Router Setup
    • Calibrations
      • Temperature Calibration
      • Optical Density Calibration
      • Pump Calibration
      • Manual Calibration - calibrate.py
  • Upgrade Base eVOLVER Hardware
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    • Starting an Experiment
      • Carboy Media Prep
      • Preparing Vials
      • Setup Waste Carboy
      • Sterilizing Lines
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      • OD Blank
      • GUI Start Guide
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      • Cleaning Up After Experiment
    • Growth Curve
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    • Use the GUI to Control Parameters
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    • Arduino Software Installation
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    • Millifluidics Guides
      • Designing Millifluidics Using Eagle
      • Constructing Laser Cut Millifluidics
      • Constructing Millifluidics via SLA Printing
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  • Troubleshooting
    • Troubleshooting Overview
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      • Contamination
      • Vial Overflow, Pump Failure, and Spills
      • Tubing and Connector Blockage and Bursting
    • Optical Density (OD) Readings
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      • Replacing Photodiodes and LEDs
      • Heating Element
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      • Motherboard Troubleshooting/Replacement
      • 12V Power Supply Troubleshooting/Replacement
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  • Hardware
    • Overview of Hardware Architecture
    • Overview of Fluidics
      • Tubing and connectors
      • Peristaltic Pumps
      • Fluidics box
    • Overview of Millifluidics
      • IPPs (Integrated Peristaltic Pumps)
      • Pressure Regulator
    • Vial Caps
      • Universal Vial Cap Construction Guide (Luer Connectors Only)
      • 5 and 7 Port Nylon Tubing Caps Construction Protocol
    • Smart Sleeve
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      • 🌪️Stirring
      • Temperature
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        • OD90 vs OD135
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      • 🌡️Arduino
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      • eVOLVER.py
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      • Power Supply
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      • ePACE
        • ATTiny1634 Writing
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      • Morbidostat
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        • Experiment Start
          • Sterilizing Extractor Fluidics
          • Setting up your experiment
          • Using the extractor script
        • Extractor Analysis
        • Troubleshooting
        • Example protocols
      • Phototroph Growth
        • Setup Phototroph eVOLVER
        • Photo-eVOLVER Smart Sleeves
          • Photo-eVOLVER Smart Sleeve Construction Guide
        • Experiment Guide
    • Custom Fluidics
      • Adding a Third Pump Rack
      • Bubblers / In-Vial Aeration
        • Bubbler Construction Protocol
        • Bubbler Cleaning Protocol
      • Running the slow pumps
    • min-eVOLVER
      • About
      • min-eVOLVER Construction
        • Parts
        • Construction Protocol
      • Fluidics Setup
      • Software Installation and Startup
      • send_command.py
      • Calibrations
      • Starting an Experiment
      • ePACE with min-eVOLVER
        • [v1.1] ePACE with min-eVOLVER
      • Troubleshooting
    • Interfacing with Other Systems
  • Contributing
    • Guidelines for Contribution
    • Reporting a Bug / Hardware Failure
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      • Making a Forum Post
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On this page
  • Standard components
  • Troubleshooting and repair
  • Swapping and modifying

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  1. Hardware
  2. Overview of Fluidics

Peristaltic Pumps

Just like the digestive system!

PreviousTubing and connectorsNextFluidics box

Last updated 5 months ago

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Standard components

The standard eVOLVER peristaltic pumps (since ~2020) sourced by Fynch Bio are selected specifically to eVOLVER use. Previous pumps used with eVOLVER during its early development tended to wear out quickly and have variable flow rates, primarily due to the mechanism for rotating the rollers against the tubing to drive pump flow. The motor shaft directly turned the rollers through friction, which led to slippage and abrasion over time. The current pumps do not have drirect contact between the motor shaft and rollers, instead driving roller rotation through a gear reduction system.

This gear system drives a roller casing with fixed roller axles contained in the pump head. In this way, the pump action does not rely on friction and thus much more accurate and durable than previous pumps.

Troubleshooting and repair

Because the current pump style has been introduced so recently, very few of them have failed from wear and tear. Based on our experience with other pump styles, the most likely failure mode will be collapse or tear of the tubing inside the pump head, or shearing of the tubing on the barb outside the head. This can be solved by replacing the pump head (contact Fynch Bio) or replacing the tubing.

The induction motor inside the pump is very unlikely to fail through normal use. If there is a liquid spill on the pump array and some pumps are not spinning, the most likely cause is corroded contacts with the pump array PCB. While the pumps themselves will be fine, they should be removed and replaced to a new PCB, ordered from Fynch or PCBWay. This will require removing solder, which can be tricky.

Swapping and modifying

The pump heads can be rotated 90 degrees in any direction, should your bench setup require changing the direction your pumps face.

The low-flow pumps available through Fynch use an additional gear reduction box to reduce the speed of pump action by a factor of 45. This is useful for addition of inducers, antibiotics, or other media feeds that require a small and precise bolus.

Plenty of other peristaltic pumps are suitable for eVOLVER, so long as they operate at 12V.

The flow rate of eVOLVER pumps (and any pump with an induction motor) is somewhat modifiable through PWM modulation. This effectively reduces the voltage going to the pump, which will slow its rotation, down to the point where the coils can't generate enough torque to consistently turn the shaft. This happens about halfway through the PWM range (around 2000), where you can get the pumps to run at about 1/3 speed. This is rarely necessary for experiments, so it has not been optimized, but is a potential feature for users to explore.

Inside the pump head, the pump tubing can be removed and inspected. The tubing is 2x4mm Pharmed BPT, which has similar chemical compatibility as the silicone tubing for the rest of eVOLVER fluidics, and is rated to over 1000 hours of operating life. Learn more here:

Pharmed BPT can be purchased from Saint-Gobain suppliers. However, the tubing should be 2mm ID and 4mm OD, and there is not enough tolerance to allow for similar non-metric sizes (like 1/16"x1/8"). 2x4mm Pharmed tubing is difficult to find in the US, and we are working on finding a reputable supplier for it. In the meantime, these alternatives from McMaster-Carr have been tested to seal and pump properly: and

https://www.biopharm.saint-gobain.com/components/fluid-transfer/pharmed-bpt-tubing
https://www.mcmaster.com/5102K11/
https://www.mcmaster.com/7027N11/