Results and Future Work

Component 1: Pulse sensor

• Specifications: That the pulse sensor should be able to measure a pulse to ±4 bpm; that is, ±1 beat every 15 seconds.

• Constraints: The sensor should be attached using a constant force, such as a velcro strip of uniform length, to replicate real, rather than ideal, operating conditions.

• Materials:

  • Prototype

  • Stopwatch

• Procedure:

  • The prototype will be assembled according to standard operating procedures. The pulse sensor will be connected to the thumb of the test subject (Student #1) by means of a velcro strip. The tethered board will give some signal when a pulse has been detected (e.g. blinking LED, output on computer screen).

  • Student #2 will use a stopwatch to measure 15 second intervals. During each interval, Student #2 will count the number of times the prototype gives the determined signal. At the same time, Student #3 will measure the pulse of Student #1 independently, on the wrist of the opposite hand, to establish a control group. This test will be repeated 2 more times while the subject is seated and resting.

  • In between the third and fourth tests, Student #1 should perform some light exercise (e.g. jumping jacks or jogging in place) to raise his/her heart rate. The test will then be repeated three more times, for a total of six trials.

• Data presentation

  • The results of the six trials should be tabulated, showing the calculated BPM, standard deviation, and statistical difference from the control groups.

Component 2: Strain gauge for breathing rate

• Specifications: That the component be able to count breaths taken within a 10% error margin.

• Constraints: The strain gauge should be placed around the subject’s chest, in real use conditions.

• Materials:

  • Prototype

  • Data acquisition device

• Procedure:

  • The prototype will be assembled according to standard operating procedures. One part of the system will be wrapped around the subject’s chest, while the other part will be around the subject’s diaphragm. The average of both parts will be used to calculate the breath count.

  • The subject will manually count their breaths in a 60-second period. This number will be cross-checked with the number calculated by the device.

  • We will test 3 different cases in 2 different activity modes: rapid, shallow breathing; slow, deep breathing; and normal breathing. The activity modes are breathing at rest, and breathing while in motion. For ease, we will have the subject jog in place while connected to the device. Each case will be repeated 10 times, with a 1-minute interval between tests, for the instrument to recalibrate.

• Data presentation:

  • The results of the trials should be tabulated, showing manually counted breath rate, device-measured breath rate, and statistical analyses.

Component 3: Electrocardiogram sensor

• Specifications: That the EKG should be able to measure a pulse to ±4 bpm; that is, ±1 beat every 15 seconds.

• Constraints: The electrodes should be placed under the clothes, in real use conditions, using the full length of wires.

• Materials:

  • Prototype

  • Stopwatch

• Procedure:

  • The prototype will be assembled according to standard operating procedures. The two electrodes will be placed on the Left Arm and Right Arm of the test subject (Student #1) in order to read EKG Lead I. The tethered board will give some signal when a pulse has been detected (e.g. blinking LED, output on computer screen).

  • Student #2 will use a stopwatch to measure 15 second intervals. During each interval, Student #2 will count the number of times the prototype gives the determined signal. At the same time, Student #3 will measure the pulse of Student #1 independently, on the wrist of the opposite hand, to establish a control group. This test will be repeated 2 more times with the subject seated and resting.

  • After the third test, Student #1 should perform some light exercise (e.g. jumping jacks or jogging in place) to raise his/her heart rate. The test will then be repeated three more times, for a total of six trials.

• Data presentation

  • The results of the six trials should be tabulated, showing the calculated BPM, standard deviation, and statistical difference from the control groups.

Component 4: Temperature sensor

• Specifications: That the temperature sensor should be able to measure a body temperature to ±1℃.

• Constraints: The sensor should be placed in the correct position on the test subject, in order to obtain the most accurate test data.

• Materials:

  • Prototype

  • IR digital thermometer

• Procedure:

  • The prototype will be assembled according to standard operating procedures. The thermistor will be taped to the axilla of the test subject (Student #1). The tethered board will track the measured temperature on the computer screen, and log the data.

  • Student #2 will use a stopwatch to measure 15 second intervals. After each interval, Student #2 will record the current temperature displayed on the computer. At the same time, Student #3 will use the digital thermometer to measure the temperature of Student #1 independently, to establish a control group. This procedure will be repeated every 15 seconds over a period of two minutes (120s) with the subject seated and resting.

  • After the two minutes are up, Student #1 should perform some light exercise (e.g. jumping jacks or jogging in place) to raise his/her body temperature. The test will then be repeated over another two minute period, measuring the temperature at 15 second intervals.

• Data presentation

  • The results of the trials should be tabulated, showing each measured temperature and the error value between them. The average error, and standard deviation of the error, should also be reported.

Component 5: Electroencephalogram sensor

• Specifications: That the EEG should be able to measure the subject’s blinking rate to within ±8 blinks per minute, or ±2 blinks per 15 seconds.

• Constraints: The electrodes should be placed in physiological relevant positions, such as they would be inside a helmet, and wherever possible imitate real operating conditions.

• Materials:

  • Prototype

  • Stop watch

• Procedure:

  • The prototype will be assembled according to standard operating procedures. The three electrodes will be placed on the left and right side of the test subject’s forehead (Student #1). The tethered board will give some signal when a blink has been detected (e.g. blinking LED, output on computer screen).

  • Student #2 will use a stopwatch to measure 15 second intervals. During each interval, Student #2 will count the number of times the prototype gives the determined signal. At the same time, Student #3 will observe the number of times Student #1 blinks, to establish a control group. This test will be repeated 2 more times with the subject resting, and doing something idle like reading.

  • The test will then be repeated three more times, for a total of six trials. During the fourth through sixth trials, Student #1 should try to vary his/her blinking, such as blinking rapidly, going several seconds without blinks, etc.

• Data presentation

  • The results of the six trials should be tabulated, showing the calculated BPM, standard deviation, and statistical difference from the control groups.

Unfortunately, due to the emerging Covid-19 situation we were unable to complete any of our desired testing. However, we compiled our observations gathered during the construction of the prototype

• Pulse sensor:

  • From our tests, this sensor worked quite well. The timing of the sensor was very good and there was little lag.

  • We found the sensor to be moderately sensitive to orientation and applied pressure. The magnitude of the analog signal could range from 400-700 depending on the timing of the pulse and location of the sensor. Calibration of this sensor would have been aided by establishing a standard for attaching this sensor to the fingertip to determine a threshold value for peak detection.

  • We did not test this component at heart rates above resting level, but we have no reason to suspect that the performance would be significantly decreased.

• Breathing sensor:

  • • The sensor worked well. It was able to detect changes in the resistance with moderate precision and accuracy.

    • One limitation of the system is its relatively low sensitivity. It seems that there needs to be a large stretch in order for the resistance to change. This could be a problem in actual testing if the subject takes shallow breaths. Calibration of the sensor is recommended.

    • Noise was not a problem in the preliminary testing, however it will probably be a significant source of error in real conditions.

• ECG sensor:

  • From our tests, we were not able to get this system working. The output on the screen only showed noise. We double-checked the wiring of our amplifier, and believe that this problem is either due to the sensitivity of our ADC, or that the electrical contact from our electrodes is not strong enough.

  • We did not test this component at heart rates above resting level, but we have no reason to suspect that the performance would be significantly improved.

• Temperature sensor:

  • This system worked reasonably well. There was surprisingly little latency, and the range of the signal was quite broad, easily able to handle the temperature change from room to body temperature.

  • The signal actually went down as the temperature went up, which is not surprising because we used a simple voltage divider. This is only a matter of calibration, which we were unable to perform, but the ratio appeared to be about 160Ω/℃.

  • We did not attempt to test this component at temperatures above resting levels, but we have no reason to suspect that the performance would be significantly impacted, as there was plenty of range to spare.

• EEG sensor:

  • From our tests, we were not able to get this system working. The output on the screen only showed noise. We double-checked the wiring of our amplifier, and believe that this problem is either due to the sensitivity of our ADC, or that the electrical contact from our electrodes is not strong enough.