Symptoms:

Various. Tips not dispensing, failing to dispense part-way through a run, or creating over-sized spots.


Causes:

There are many potential causes some are:

  • Hardware or control baord failure
  • Sub-optimal aspiration settings
  • Sub-optimal dispense settings
  • Not using an air gap when working with volatile solvents and/or solutes that can precipitate in water
  • Blocked tip
  • Damaged tip
  • Tip has become hydrophobic
  • Air in fluidics lines
  • Leaking dilutor syringe
  • Blocked frit filter
  • Blocked PCV filter
  • Contamination in lines
  • Damaged fliuidics lines
  • Failing dilutor pump


Troubleshooting:


  • Hardware failures will be detected by the system in 90% of cases. Follow instructions in "Error Reporting" article.
  • Aspiration/dispense settings are customer/application specific. Instructions for optimising aspirartion and dispense settings are in the Short Manual, chapter 2.11.1, Pipette check in the stroboscope, and chapter 6, Troubleshooting and Maintenance.
  • Air gaps - required to prevent volatile solvents mixing with system liquid or preciptiating warter-insolluble solutes in system liquid (and causing blockages). Instructions on how to correctly configure the air gap settings can be found in Short  Manual, chapter 5.10.10, TSMP 08: air gap pipetting.
  • Blocked tip - solids may be visible in the tip, possibly when examining with a magnifier. Replace tip with spare/new tip and return blocked tip to GeSiM for inexpensive resotration.
  • Tip has become hydrophobic - on some cases the inner sufrace of the tips can come hydrophobic and fail to hold the meniscus inside the end of the nozzle. This  can cause air to enter the tip and results inunstable dispense. It is more likely for a tip to bbecome hydrophobic if it has been stored for an extended time. This will be visible in the stroboscope images which may show the miniscus on the outside of the tip, or air bubbles in the end of the tip. Follow instruction from NanoPLotter "unstable tip" error article in our knowledge base.
  • Air in lines - air bubbles may be visible in the lines. These will compress when the pumps actuate, and incorrect volumes will be dispensed. 
    1. Make sure that PCV fill level matches level the the tips are positioned at in the NanoPlotter.
    2. Use the "empty tubing" function, followed by the "complete fill tubing and tips" funtion to purge all air from lines. 
    3. Examine lines to make sure that all air bubbles have been removed. Repeat emptying and filling if air bubles persist
    4. If it is not possible to remove the air bubbles after repeated filling and emptying, then there is likely to be a leak in the fluidics. If the leak can be located, then the leaking connection should be tightened or the damaged part replaced.
  • Leaking diluter syringe - leaks may be visible during filling of the fluidics lines when large volumes are being pumped. There may also be evidence of leaks on or below the syringe (water marks, mould lines down the sides of syringe seals, etc.). Replace syringe.
  • Blocked frit filter - these are the small green 2um filters between the tubing from the diluter and the tubing to the pipettes. Contaminants in the lines can easily blind these filters. 
    • This can be diagnosed by emmtying and filling the tubes, and observing the movement of the miniscus though the line, particularly in the tubing between the tip and the frit.
    • Normally the minisucus should move in synchrony with movemnt of the dliuter pump.
    • If there is a delay in the movement of the miniscus, then frit is porbably blocked and should be replaced.
    • It is also advisable to change the PCV filter and clean the PCV if the frit is blocked, as there may be contaminents present which could cause further blockages.
  • Blocked PCV filter - [tbc]
  • Contamination in lines - biofilms or precipitated solids may be visible in fluidic lines - replace contaminated tubing, clean contaminated diluter valve, syringe, vessels and replace frit filter.
  • Damaged fluidics lines - small leaks may cause air bubbles to enter lines. Replace damaged tubing.
  • Failing diluter pump shoud be recognised by the system and recorded in the log. In some cases, the dilter pump may need to be returned to the manufacturer for evalutaion and repair.