F7ABBPNK - Design and Construction of Medical Devices/Practical Exercises

The aim of the practically oriented course is to acquaint students with the design process of the measuring part of the device, ie basic problem analysis, determination of functional blocks and their design, selection of suitable components and their values with emphasis on working with catalog sheets and application recommendations, preparation of electrical documentation and board design. printed circuit board, its mounting, soldering and revitalization. During the course, students will implement a functional device (mounting, soldering, recovery) electronic thermometer, which will consist of two functional units - analog part for temperature measurement and signal conditioning (equipped with THT components) and display element with diode bargraph (equipped with SMT components ). For both products, students will implement the design of the diagram and PCB in the CAD environment EAGLE. In addition to the analog part of the device, an application for digitizing data from the analog device using NI-DAQ cards and a cheap solution with the help of Arduino will be implemented. The last part will be a service intervention in the device (monitor of vital functions) with emphasis on safe handling and measurement of test points.

TCourse prerequisites:

Understanding of schematics and knowledge of basic circuit calculations passive components (resistor dividers, RC and RL cells, resistor bridges), active components (diodes and Zener diodes), operational amplifiers (connections as followers, inverting and non-inverting amplifiers, differential amplifier, and instrument amplifier). Basic knowledge of working with laboratory instruments digital multimeter (measurement of U, I, R parameters), laboratory power supply (voltage and current limit settings), oscilloscope (manual parameter settings range, time base, triggering), and signal generator.

The course is completed with a graded credit.

The course is evaluated on the basis of an independent assignment and a final test with a practical exam. The independent assignment involves designing a schematic and printed circuit board in Fusion, with each student being assessed on the basis of the submitted materials the schematic and PCB exported to PDF as accompanying documentation. All aspects of correct documentation are assessed, with points deducted for inaccuracies and errors in the design. The maximum total number of points that can be earned is 20.

The final test focuses on the material covered in the course and consists of the following parts: a numerical example requiring the parameters to be read from the component catalog sheet, a circuit diagram design with a selection of components from a defined series, and theoretical questions with one correct answer. Students can earn a maximum of 40 points (15 points for the numerical example, 15 points for creating the diagram, and 2 points per question, i.e., a total of 10 points for questions, for a total of 40 points for the test). The time allowed for the test is 30 minutes.

The practical exam takes place immediately after the test. Students draw a circuit from a set of predefined tasks and are tasked with independently implementing this circuit, including, for example, calculating the necessary circuit components. The correctness of the circuit will be evaluated by the instructor after measuring the significant points in the circuit. Students must be able to calculate, or at least approximately estimate, the voltage/current at this point. The maximum number of points for the practical exam is 40.

Students can earn additional bonus points beyond the tests for designing, implementing, and activating their own PCB necessary for completing the task within the course.

The final grade is determined by the sum of points from the test, individual assignment, practical exam, and any bonus points. The final grade is given on the ECTS scale.

The minimum number of points is 50, i.e., grade E, and the maximum is 100, i.e., grade A, according to the SZŘ ČVU (Study and Examination Regulations of the Czech Technical University in Prague).

Two unexcused absences are permitted in this course.

Course has no lectures.

Exercises take the form of 4 hour blocks

1. Problem analysis (electronic thermometer with NTC), design of functional block connections (connection of resistive thermometer to divider and bridge, power supply and voltage reference, amplification), choice of components based on calculation and availability from the series, work with catalog sheet

2. Verification of the proposed connection (electronic thermometer with NTC) and its stability in a non-soldering field.

3. Schematic design in EAGLE environment, choice of components and packages, circuit simulation in Multisim environment (SPICE).

4. PCB design in EAGLE environment, methods of manual component layout, autorouting and manual path guidance, export for production.

5. PCB production by photo path, PCB mounting and soldering of THT components - thermometer board with NTC

6. Revitalization of the produced board, measurement at nodal points, fault finding, measurement of transmission characteristics.

7. Manual soldering of SMT components, application of solder paste through the mask, mounting and remelting, optical analysis of soldering - imaging element board to the thermometer.

8. Recovery and testing of the activated set (thermometer board and display element board), use of the system for automated tests TestStand in combination with a data card for verification of operation in different conditions and stress test (simulation of different temperatures, different battery voltages)

9. Creation of a measuring application in the LabVIEW environment for digitization of data from a manufactured jig using an NI-DAQ industrial converter.

10. Digitization using available solutions (Arduino) and data display in the terminal and LabVIEW

11. Connection of instrument amplifier for sensing biopotentials - ECG, EMG and EOG, data digitization

12. Signal amplification from electrochemical sensors - pH and conductivity, temperature compensation, detection of maximum peaks.

13. Service intervention in the monitor of vital functions, safety during handling and use of isolating transformer, analysis of function blocks, measurements on test nodes for setting operating values, assembly of the device and verification of operation

14. Consultation of the subject, reserve for additional assessment of tasks, graded credit.

Orientation in technical documentation (data and sheets, application recommendations); design of electrical documentation in the EAGLE environment (electronic diagram and printed circuit board); PCB production; soft soldering of THT and SMT components; safe ESD work; implementation of a simple application for signal digitization based on NI-DAQ and Arduino in the LabVIEW environment and data export; service intervention in the device (analysis of functional blocks, safety during handling, measurement at test points)

[1] Medical instrumentation: application and design. 4th ed. Editor John G. WEBSTER. Hoboken, N.J.: Wiley, c2010. ISBN 9780471676003.

• Prospectus - bakalářský (!)
• Biomedical Technology (compulsory course)
• Biomedical Technology (compulsory course)