Minimally Invasive Surgery and Interventional Techniques
Department of Biomechanical Engineering - Delft University of Technology
Contact Arjo Loeve
DropAdjust: simplifying infusion control
07 October 2020


During the corona crisis early 2020, many hospitals worldwide experienced serious issues due to shortages of crucial devices. Many of the patients staying in a hospital receive some kind of infusion therapy. This ranges from fluids for hydration–administered by liters–to concentrated medication at a few ml per hour. Depending on infusion volume and flow, three types of infusion systems are used:


Gravity infusion: a bag or bottle placed at ~1.80m height, with an infusion line (tube) running to the infusion needle in the patient and a small wheel on the tube to manually control the infusion flow (€ 3-4 per disposable set). The flow in ml/hour is roughly determined by counting the number of drops leaving the bag in 30 s. Only about 26% of users manage to set the flow within 10% of the target.


Volume pumps: similar to gravity infusion, but with an electronic pump placed on the infusion line to actively control the infusion flow. The desired flow is set by the healthcare professional and the pump controls large infusion flows with an accuracy of about 5%. Such pumps cost € 1500-2000.


Syringe pumps: a syringe with 5 to 60 ml medication, connected to the infusion line, is placed in the pump, which precisely controls the user-set desired low infusion flow with an accuracy of 3-5%. These pumps are very accurate, but only apply small volumes at low flows and cost up to € 2500.


So these systems have varying accuracy, cost and user friendliness. However, large volumes and infusion flows are often used with non-critical fluids and medication. In these cases gravity infusion requires frequent manual checks or doesn’t deliver the required accuracy or stability, whereas infusion pumps are cost inefficient and may quickly be unavailable during crises such as the corona pandemic.

Recently, the MoniDrop (€ 500) was put on the market to partly close this gap: a drop counter that can be placed on a manually controlled gravity infusion line and that shows the infusion flow in convenient units. Yet, the manual control wheel on infusion lines still makes setting a correct flow difficult.

Teamed with TU Delft and the Jeroen Bosch Ziekenhuis, QRS healthcare develops the DropAdjust: a manual control device for improving the accuracy of manually set infusion flows. Combined with the MoniDrop it should provide a sufficiently accurate infusion control system at only a fraction of the cost of volume pumps. This will reduce healthcare technology costs while increasing the gravity infusion safet. The current DropAdjust design has shown to enable manual control as accurate as a volume pump. However, it is not yet suitable for practice, and should be much simpler and easier to produce.


  1. Review the current DropAdjust design and performance.
  2. Improve or replace the current design, focusing on manufacturability, cost and usability.
  3. Test the improved prototype to prove its performance and help making the device market ready.

Additional info

Budget is available, so we like to see you deliver a practice-ready prototype. You will have to sign an NDA & IPR-transfer to ensure continuity of the project towards helping patients in practice.


Supervisor TUD: Arjo Loeve, TUDelft - 3mE - BMechE, (contact)

Supervisor JBZ:  Marit van Velzen, Jeroen Bosch Ziekenhuis,

Supervisor QRS:          Ewoud Kooijman, QRS Healthcare,

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