Although syringe and piston techniques are popular for microinjection in the nanoliter range, microinjection of sub-nanoliter volumes through a very small opening in a glass micropipette is often better accomplished with a controlled burst of gas pressure. Designed to simplify intracellular injection and a variety of other microinjection tasks, WPI’s PicoPumps use precisely regulated 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. In the time between injections, a secondary default “hold” pressure is applied to the pipette to prevent fluid uptake through capillary action or diffusion. The pressure pulses are typically controlled by a precision timer. Timing, ejection pressure, holding pressure and suction are adjusted independently by control knobs and monitored with indicator gauges on the front panel. Injection pressure is controlled by a 20-turn regulator on the front panel. The built-in timing function controls the amount of time that the injection pressure is applied with millisecond resolution. Time intervals can range from 10 s down to 10 ms or less. The pressure burst can also be controlled manually or triggered by an external source.
The PV830 model provides separate regulation and pressure gauges for the eject and hold pressures. In addition to the features of the PV820, the PV830 model also includes a vacuum pressure regulator and vacuum gauge.
PicoNozzle Kit 5430-ALL (included) allows micropipettes to be securely mounted in micro-positioners for stable axial air delivery.
The optional 5430-XX PicoNozzle Kit has a Luer-fitted pipette holder for quick and easy changes. Choose your kit based on the pipette OD (XX indicates OD: 1.0, 1.2, 1.5 or 2.0 mm). The red handle has a larger diameter so that it fits easily into most manipulators. This kit contains:
(1) MPH6S microelectrode holder
(1) Handle for the MPH6S (4" hollow tube with male Luer fitting at both ends-handle diameter is 6.25 x 100 mm.)
(1) 5’ tubing (0.060" ID, 0.120" OD, male locking Luer fitting on one end and a female locking Luer fitting at the other end, rated for 200 PSI and 86 durometer shore A)
Hold Pressure Prevents Backfilling
Like the PV830, the PV820 was designed to simplify intracellular injection. The hold pressure prevents backfilling of the pipette by capillary action. Simple to use. Reliable every time.
Each PicoPump is supplied with a 5430-ALL kit that includes two PicoNozzles and tubing to connect the holders to the pressure and vacuum ports.
Vacuum Pressure for Additional Applications
Eject pressure supplies a high-pressure pulse for injecting fluid. Hold pressure, which is not sufficient to cause fluid ejection, is used to prevent back filling of the pipette by capillary action or diffusion when the solenoid is inactive. Vacuum can be applied through the ejection port, but vacuum in the PV820 must be externally regulated. To fill pipettes from the tip or through a secondary port to secure a floating cell during microinjection, vacuum may be switched from regulated vacuum to atmosphere by using the switch on the front panel.