THE STATE UNIVERSITY OF NEW JERSEY
RUTGERS
Cardiovascular Dynamics Lab • Department of Biomedical Engineering
617 Bowser Road • Piscataway • New Jersey 08854-8014 •
732/445-3727 • FAX: 732/445-3753 • e-mail: drzewiec@biomed.rutgers.edu
Time Signals for
Physiological Modeling
Aim: In this experiment, we simultaneously record a blood pressure pulse waveform
and attempt to model it with a sinewave from the wave generator.
Modeling of Physiological Waveforms:
Connect the PPG to Channel 2 of the Biopac system. Wrap the pulse
transducer around the tip of your index finger. The transducer should fit
snuggly, but not to the point where your blood circulation is impaired.
Calibrations are not necessary in this experiment. It will be best that one
partner in the lab group wear the PPG while the other adjust the instruments.
From the Setup Channels menu check the three option boxes and select PPG
(0.5-35Hz) preset. Channel 1 should record the output of the Tektronix sine
waveform generator while Channel 2 records from the pulse (PPG) sensor.
Adjust the function generator output to model the physiological signals as
best as possible. Also, adjust sampling rate and other parameters
accordingly.
For the simplest set up, it is best to verify that the PPG channel and wave
generator channels are working separately before a recording of both is
performed.
After you have verified that you can separately record a sinewave and a
pulse wave, set the Biopac to record both channels simultaneously. One lab
partner will adjust the frequency and amplitude of the sine-generator such
that it matches the pulse wave as best as possible. The best way to start will
be to first measure the pulse frequency in Hz then, set the wave generator
frequency to the same value. It is best that the lab partner providing the
pulse be still and breath regular (no joking around).
After you have what you find is the best result, print your data and record
the key waveform measures like [p-p, max, min, frequency] for both the
pulse and sinewave.
Lastly, place the Biopac window into the scope display made by clicking
the scope button on the top of the window. Print this result. Exit the scope
mode and then use your measurement tools to find the pulse period for 5
heartbeats. Save that data in your notes.
SIMULINK EXPERIMENT
Use the SIMULINK software to model the pulse data with a sinewave. Pay
attention to key timing data points and max and min values from your pulse
recordings. For example, pay attention to the correct frequency, wave shape,
and zero crossing times. You will be evaluated based on the accuracy of
your SIMULINK model’s representation of your acquired waveforms.
REPORT
1. Provide your SIMULINK results for the Sine waveforms and all biopac
graphs
2. Discuss the problems that you had in attempting to model the pulse
3. Calculate the average heart rate for your subject over 5 heartbeats. By
what percentage did the heart rate increase or decrease over the 5 beats?
4. Is the sinewave generator a good model of the heart rate process?
Discuss.
5. Prepare a written summary of your lab and discuss its relevance to your
lecture materials.