Pumpy Using the pumps
The pumps are designed for relatively slow movement, to allow for small volumes to be injected. This means that whenever the syringe needs to be replaced it would take too long to have the linear actuators retract to allow the current syringe to be removed. Therefore, the pump design allows the linear actuators to be moved manually as well as automatically.
To manually move the linear actuators, the motor needs to be disengaged. To do this, we pull away the axle that connects the motors to the speed reducing gears, freeing the gears to be moved manually.The axle should be pulled out only until it rotates freely. If it is pulled too far, the small gear that it connects to might come off. We can then use the long axle to move the linear actuators.
This process is clear in the video below. The axle in front of the pump is not connected to the motor at the beginning; this allows the gears to move. Once the axle is pushed into the pump, the gears are locked and engaged with the motor.
Please note, the motor doesn't need to be removed to be disengaged. It is shown out of the pump at the beginning of the video because it is part of the pump assembly instructions page.
Once the linear actuators have been fully extended, the syringe plunger stopper needs to be adjusted for the size of the syringe, as shown in the image below.
To load a syringe onto the pumps:
- Remove the syringe plunger stopper. This is the piece that sits above the syringe plunger (the red piece made with lego planks in the above images).
- Place a rubber band on the end of the linear actuators.
- Place the syringe between the rubber band and the linear actuators.
- Adjust the linear actuators using the red axle shown above, until the syringe plunger sits flush against the pump.
- Adjust the syringe plunger stopper for the size of the syringe and replace it one the pump.
You may need to readjust the liner actuators manually again before starting to pump. Otherwise, you may now use the software to start pumping.
Single pumps tend not to be able to keep the large syringes (>10ml) in place. However, when we use the multiplexed pump array this is less of an issue, as the extra rigidity provided for the supports is enough to keep the syringes in place.
The plunger on the 1ml BD syringes can bend since the plastic isn't very strong. For lower volume plastic syringes, we tend to prefer 2ml syringes.