ElectrocardiographWei Lin

Department of Biomedical EngineeringStony Brook University

Instructor’s Portion

SummaryThis experiment requires the students to build a electrocardiograph based on the previous projects of instrumentation amplifier and high-pass/low-pass filters. The students are required to build a sub VI that can measure the heart rate from the collected ECG signal.

UsesThis lecture applies to all courses of virtual instrumentation.

Equipment List Computers

LabVIEW 7 Express

NI-ELVIS benchtop workstation

References LabVIEW User’s Manual. April 2003

LabVIEW Introduction Course - Six Hours .

LabVIEW Introduction Course - Three Hours

VIs from the project “Data Acquisition Using NI-DAQmx”

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Student’s Portion

IntroductionThe students will build the electrocardiogram (ECG) amplifier based on the provided schematics diagram. They will develop a VI that can detect the R wave in the ECG signal and convert the R-R interval into heart rate. The ECG amplifier will be based on the circuits developed in the previous projects of instrumentation amplifier and filters. The students will modify the data acquisition VIs developed in the previous project titled “Data Acquisition Using NI-DAQmx VIs” to collect ECG and measure heart rate.

Objectives ECG amplifier Data acquisition using LabVIEW Data analysis using LabVIEW

TheoryThe basic ECG amplifier consists of two components. The first component is the instrumentation amplifier with typical gain of 1000 (60dB). The second component is the band-pass filter. The low cutoff frequency is around 0.5Hz to minimize the baseline shift. The high cutoff frequency is around 100Hz for antialiasing purpose.

Lab Procedure1. Keep ELVIS workstation power off.2. Locate the instrumentation amplifier on the prototyping board and

identify the resistor R4 and R5. Replace the resistors with resistors of 10k

3. Connect the output of the instrumentation amplifier to the input of the high-pass filter.

4. Connect BANANA A on the prototyping board to the positive input of instrumentation amplifier (Pin 3 of LF353)

5. Connect BANANA B on the prototyping board to the negative input of instrumentation amplifier (Pin 5 of LF353)

6. Turn on the ELVIS workstation.7. Place ECG electrodes on the wrists of both arms and connect the

electrodes to the connectors (BANANA A & B) of the ELEVIS station.

8. Launch LabVIEW and ELVIS.9. Measure the frequency spectrum of the amplifier by measuring the

gain at multiple frequency points.10. Use ELVIS scope to check the ECG signal.

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11. Using finite data acquisition VI to record ECG signals12. Modify the continuous data acquisition VI measure the heart rate. The

sub VI for the measurement of heart rate should be finished before the lab. Students are encouraged to develop their own algorithms.

Lab ReportThe lab report should contain the following:

1. The experiment title2. The experiment objective3. The experiment procedure and theory. Experiment results, which

include the plot for frequency spectrum (gain vs. frequency).4. Discussion5. You may add your lab design into this project.6. You must submit the sub VI for the heart rate measurement with the

description of use.

Please submit the report through email.

Appendix

Filter schematics

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