Designed to simplify intracellular injection and a variety of other microinjection tasks, WPI's PicoPumps use carefully regulated air pressures for securing cells and injecting them with fluid. Injected volumes range from picoliters to millilitres. 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—available in models PV820 and PV830—maintains a low positive “holding” pressure to the injecting pipette between injection pulses, to prevent fluid uptake through capillary action or diffusion. Timing, ejection pressure, holding pressure, and suction are adjusted independently by control knobs and indicator gauges on the front panel. Injection pressure is controlled by a 20 turn regulator on the front panel. A built-in timing circuit allows precise control of the amount of time that the injection pressure is applied to the output port. Time intervals can range from 10 seconds down to 10 ms or less, depending on the eject pressure setting. The injection pressure interval can be triggered manually on the front panel, by footswitch, or by computer controlled TTL pulse. A 5-volt monitor output provides a logic-level pulse for your computer or other monitoring device.

PV830 combines the features of the PV800 and the PV820. Eject pressure, Hold pressure, and Vacuum are all available, controlled by separate regulators on the front panel. 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. Pressure in the injection pipette is automatically switched between Eject and Hold pressure by a precision timing circuit that controls a solenoid valve. Eject pressure is controlled by the range switch and 20-turn regulator knob on the front panel. Vacuum is used to fill pipettes from the tip or to secure a floating cell during microinjection. Vacuum is regulated the same way, by a 20-turn knob on the front panel. Vacuum may be switched from regulated vacuum to atmosphere by using the pneumatic toggle on the front panel. Ejection or suction can be timed manually, using the Start button or a footswitch (optional), or timing can be preset on the front panel by using the Range switch and Period knob, or by computer.

PV820 adds to the basic unit a regulated Hold pressure, used to maintain a low pressure in the pipette between injections to prevent unwanted fluid uptake by capillary action or diffusion. A precision timing circuit switches from Eject pressure to Hold pressure automatically, once timing has been set. Although regulated vacuum is not provided in this model, suction can be provided by connecting a vacuum source to the vacuum port on the rear panel. Suction is then available through the pressure ports. Ejection/suction can be timed manually, using the Start button or a footswitch (optional). Timing can also be preset by using the Range switch and Period knob on the front panel, or by computer.

Using PV830 for holding and injection of cells