Model 2: Syringe Pump

It’s all about the dose!

Grade level

11-13

Time required

3 double hours (extendable to 6 DS)

Degree of difficulty

Model: medium, programming: medium

Model Type

Benchtop model for syringe pumps

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MODEL DESCRIPTION/TASK

The students plan and implement a medical syringe pump for fine dosing of medication.

The control elements such as selection buttons and display elements are programmed on the touch display. The dosing is precisely achieved by stepping an encoder motor.

Two LEDs give light signals during dosing mode (green) or in the end position and when the fluid volume is too low for a dose (red). Various functions such as “Start”, “Return”, “Dose preselection” and “Injection time” are implemented step-by-step via touch buttons. The number of motor revolutions is used to determine the dose currently injected and the remaining amount of drug in the syringe, which is then displayed on the screen. If the remaining quantity is not sufficient for a preselected dose, the start is prevented. Similarly, the motor stops when the syringe is fully inserted. In both cases, the red LED flashes.

The syringe drive returns to the start position and stops automatically when a specific request is made to change the syringe and automatically when the program is started.

EVERYDAY RELEVANCE

Medical syringe pumps are precise dispensing devices that deliver drugs or fluids in precisely controlled amounts over a specified period of time. They are often used in medicine, for example in anaesthesia, intensive care or pain therapy.

In addition, syringe pumps can be used for precise dosing in biological or chemical experiments and manufacturing processes.

Key Questions

Where can an automatic medical syringe pump be used in everyday life? (Communication)
Which functions does the syringe pump control system have to fulfil sensibly? (Collaboration)
Under what conditions should the system move the syringe? (critical thinking)
What needs to be considered so that the control can be used at different locations and the system works as robustly as possible? (Creativity)

Compartment cover

Information technology

Advanced programming, condition loops, functions

Mathematics

Conditional counting, volume and time calculation

Technology

Stable construction, construction technology

Physics

Movement change

Biology, Chemistry

Experiments with dosing tasks: In chemical and biological experiments, the syringe pump can be used as a fan-connector for precise dosing.

Course History

Conversational

The procedure for building the model and the function to be achieved are developed together.
The work steps of the app are specified or discussed.

Partner or individual work

The students familiarise themselves with the app and load the corresponding task.
The students define meaningful functions of an automatic syringe pump.
The students use the app to create the requirements list for the syringe pump to be built.

Optional partner or group work

Optionally, the students outline the possible designs of the syringe pump with further sensors (limit switches) and actuators (LED).
The students discuss the results in the group and agree on a design.

Notes and information

Methodological and didactic notes

Description of features
In medical practice, professional syringe pumps work with highly precise step-by-step dosing. Instead of allowing a fluid to flow continuously, the desired volumetric flow is achieved by repeatedly administering the smallest single doses (e.g., 0.01 mL or even 0.001 mL). This principle ensures maximum accuracy and safety, especially for highly effective drugs in intensive care or emergency medicine

Educational benefits
As a model, a microdose of 0.1 ml is specified here. Dosing in such discrete steps can be implemented particularly clearly from a programming point of view, as it can be easily translated into loops or time-controlled routines. The dosing rate can easily be adjusted by changing either the number or frequency of microdoses - considerations for this encourage an active understanding of regulation and control. In addition, the procedure for the students is intuitively understandable: It is more tangible to consider how many individual steps are necessary to dispense, for example, 1 ml of fluid than to abstractly imagine a steady flow.

Differentiation options
Depending on the working speed of the individual students, variations in the minimum dose and the injection speed can be programmed (differentiation option 1). In addition, the touch display can be extended with a slider with which the injection time can be continuously adjusted (differentiation option 2).

Motivational aspects
Working with syringe pumps combines technology with meaningful application - it’s not just about motors and sensors, but about how technology can save lives. For boys, but especially for girls, this medical-technical
Context is particularly motivating because it shows that programming and building are not abstract, but meaningful and socially relevant. Those working here work on solutions that help people - this makes technology tangible, exciting and valuable.

Supplementary materials

If available, a video could be used for the introduction phase to the topic.
Drawing media (paper, whiteboard or projection surface).

Installation Guideline

Connection Diagrams

Functions of the model and their technical solutions

Actuator/sensor functions

Technical solution

Performing a rotation of a
Encoder motors

Actuation of the drive motor for a
Rotation with fixed step size

Red/green LED light signals

Actuation of the LED for operating and
fault messages

Calculating and displaying
Information on the touch screen

Programming and evaluation of
Quantities and times

Material List

Sensors

Function

1 On/Off button on the TXT 4.0 controller

1. Switching on the syringe pump

2. Emergency stop of the syringe pump

2 mini buttons

Detecting the start and end position

Actuator

Function

1 Encoder motor

Movement

2 LEDs (1 × red, 1 × green)

Status Indicator Light