Urodynamics Without Borders

Measurement

The peristaltic pump is used to infuse fluid into the bladder via the catheter. The load cell is fixed to allow the infusion bag to be hung from it, as fluid is infused the load cell measures the weight of the bag to allow the volume infused to be calculated.

Design

The volume-infused configuration is a cantilever load cell attached to a hook that can hold the fluid infusion bag/bottle. The infusion pump is a peristaltic pump that can be connected to the fluid infusion bag/bottle. A pulse wave modulation circuit is required to control the pump’s output.

Manufacturing

Ensure the system controller has been manufactured, then:

1. Prepare the infusion load cell
   1. Solder the digital amplifier to the load cell
   2. Create the electrical connector for the digital amplifier
2. Prepare the peristaltic pump
   1. Solder wires to the peristaltic pump
   2. Create the electrical connector for the peristaltic pump
3. Prepare the infusion stand
   1. Prepare the base and main upright
   2. Secure the main upright to the base, test that the infusion stand is stable
   3. Secure the infusion load cell in the cantilever position at the top of the upright
   4. Secure the peristaltic pump halfway down the upright

Signal Processing

A load cell is calibrated to output the weight applied over time and can be used to calculate the volume infused. The rate of infusion can be tracked through the calculation of the rate of fluid infused.

The pump can be tested to identify the relationship between the input value and the flow rate delivered. This relationship can then be used to pump at a specific flow rate. The load cell output can be fed back to check if the pump is at the correct flow rate. If not, the feedback can be used to alter the pump’s input value until it is at the correct rate.

Component selection and manufacturing tips

• Loadcell
  • A maximum load of 3-5 kg
• Peristaltic pump
  • 0-100 ml/min (on the datasheet)
  • 12-24v DC input voltage
• PWM Circuit (defined in the parts list)

Validation testing

Validation tests can be performed after the previous steps have been completed.

Configuration