Affordable New Injector: Configure the PV850 Software
[by Gabe Gonzalez]
The PV850 Injector is designed to simplify intracellular injection and a variety of other microinjection tasks. The PV850 uses regulated air pressure for injecting cells with fluid. Injected volumes range from picoliters to nanoliters. The port supplies positive pressure for high-pressure ejection maximum of 8 7PSI. The PV850 Microinjector offers separate regulated compensation (back filling prevention) and ejection pressures with a precision timing circuit that switches from injection pressure to compensation pressure automatically. Timing, injection pressure and compensation pressure are adjusted independently using the intuitive touch-screen user interface. Time intervals can range from 2 seconds down to 10 ms or less, depending on the injection pressure setting. The injection pressure interval is triggered by using a foot switch, manually or a computer controlled TTL pulse. The PV850 is designed to inject very small quantities of fluids, such as drugs into cells or small organelles. Pressure injection is an especially useful alternative to electroionophoresis, since it does not mandate the use of charged ions.
After the physical connections on the PV850 Injector are made, we can walk through the intuitive touch screen user interface.
The PV850 Microinjector has two main screens, the Home screen and the Settings screen.
- Protocol - The number in the upper right corner indicates the loaded protocol. You are able to save up to 3 protocols and call them up in the Settings screen.
- Injection Counter - Every time the injector is activated it will increment the Injection Counter. Reset the counter by touching it.
Each one of the following settings (located in the center column of the screen) is controlled by touching the parameter and rotating the knob to modify the parameter. Press the knob to toggle between gross and fine-tuning adjustments, indicated by the running man and the snail on the screen. Two seconds after a parameter is adjusted, it is saved into the memory. If you move from one parameter to the next before two seconds, the first parameter is automatically saved into the memory as the working parameter. This setting will be recalled on power up. This is different from saving and loading protocols in the Settings screen.
- Pump Mode - The pump can be set to manual or timed mode.
- In MANUAL mode, the pressure valve opens and remains open as long as the Inject button is pressed, the foot switch is pressed or a 5V TTL pulse is triggered by an external pulse generator.
- In TIMED mode, an electronic timer controls the duration that the pressure valve stays open, the Inject button, foot switch or 5V TTL trigger serves only to start the timer.
NOTE: Although the timer control allows settings sub-millisecond burst intervals, the true burst interval is limited by the mechanical response of the valve, which is about 0-2 seconds, depending on the pressure.
- Injection Pressure - The injector pressure indicates the maximum pressure that will be used when the pressure is activated. The maximum that can be used is 87 psi.
- Compensation Pressure - The compensation pressure indicates the constant low pressure that is applied to make sure that no liquid is mixed with your injection solution.
- Duration - The duration indicates the time that the pressure valve will be active once it is triggered. This only works when the pump mode is set to Timed.
On the right side of the screen are the following functions:
- Clear Tip - The Clear Tip button activates a 500 ms burst of maximum pressure (87 PSI) through the injection tip. This can be used if the tip becomes clogged.
- Inject - The Inject button allows you to activate the pressure port to do your injections manually. When the port is disabled, touch the yellow Port Off button on the home screen to enable the port. The port may also be enabled in the settings screen by touching the Port On button.
- Settings - Touch anywhere in the Settings area (where the gear icon is located in the bottom right corner of the screen) to access the Settings menu.
- Pump Mode - In the Pump Mode area, choose either the Manual or the Timed radio button to determine the injection mode.
- Pressure Mode - In Pressure Mode, select one of the radio buttons to set the display to either PSI or kPa.
- Self Test - The Self Test runs whenever the unit is powered on. To initiate a test manually, press this button. It runs a series of programmed diagnostics and displays results on the screen.
- Protocols - The Save/Load Protocols allow you to store your three favorite parameter sets (protocols). On the main screen, set the parameters as desired. Then, press one of the Save buttons. For example, press SAVE1 to save the parameters as Protocol 1. To load a set of saved parameters (a protocol), press the appropriate LOAD button. The number of the loaded protocol displays in the box in the upper left corner of the main screen.
- Port Status - The Port Status button indicates when the pressure port is enabled. Port ON indicates that the injection port is enabled. To disable the port, touch the Port ON button. The button will change to Port OFF. To re-enable the port, press the Port OFF button, and the button will change to Port ON.
Back - The Back button closes the Settings screen and displays the Home screen.
The injector is now ready to use, and you can set up your injection protocols to do your microinjections. Refer to the manual for more TECHNIQUES IN MICROINJECTION.