Designed to simplify intracellular injection and a variety of other microinjection tasks, PicoPumps use carefully regulated air pressures for securing cells and injecting them with fluid. Injected volumes range from picoliters to nanoliters. Separate ports supply positive and negative pressure—positive pressure for high-pressure ejection, and suction for supporting the cell or for filling the pipette from the tip. A second pressure port maintains a low positive “holding” pressure to the injecting pipette between injection pulses, to prevent fluid uptake through capillary action. A manual for PicoPumps (we have PV800 PicoPumps in the lab) can be found here. Newer models are available:

Usage#

  • Set up the device. Check the manual for details. Fundamentally just involves connecting to air flow, and a micropipette holder with appropriate tubing.
  • Make sure you have a compatible pipette holder. Check the manual for details.
  • Make sure airflow to your PicoPump is switched on.
  • Turn the PicoPump on with the front, main switch.
  • On the eject pressure gauge, there is a ‘regulator’ knob. Turn clockwise to increase the pressure, and counter-clockwise to decrease the supplied pressure. 6 psi may be a good place to start, for many applications.
  • You will not typically use the vacuum facility. The vent switch on the pressure panel will witch from venting to atmosphere (typically this is what you want) or to the dedicated vacuum line.
  • You can control the PicoPump using MATLAB and a DAQ board, and listen in on what it does. Connect an output channel of your DAQ board to the PicoPump (EXT INPUT) , and an input channel (MONITOR).
  • The MONITOR channel should be binary, gives the times for which the pressure solenoid was energised (+5V when on, 0V when off).
  • The EXT INPUT channel can take a +5V input to effect a pressure change, i.e. pressure solenoid is opened and green light turns on. This is equivalent to pressing START (though I am not sure). Sending a +1V output via Matlab+DAQ will turn off the applied pressure, similar to hitting STOP on the machine.
  • There are two DURATION modes that you can switch between on the front of the box, GATED and TIMED.
    • GATED - pressure solenoid remains open for as long as EXT INPUT is supplying voltage (and according to the manual, START, but this does not seem to be the case unless you hold down start).
    • TIMED - a timer within the machine controls the timing of pulses, and EXT INPUT and START only serve to start the process. RANGE and the PERIOD dial are used to set the time. RANGE controls the time intervals (either 10 ms or 10 s) of the PERIOD dial.
  • If controlling with Matlab, may be easiest to used GATED mode and do the time calculations within Matlab.
  • The time at which the solenoid can be switched on and off ranges from 1 ms at 0 psi to 3 ms at 100 psi.

Dye#

You can add a fluorescent dye in order to visualise injected, pressurised fluid, e.g. an ATP solution.

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