The document summarizes various techniques for measuring respiratory rate that were presented in a seminar. It discusses methods using piezoelectric sensors, laser Doppler vibrometry, pyroelectric sensors, impedance pneumography, capnometry, and photoplethysmography. Piezoelectric sensors directly measure electric potential changes from respiratory airflow. Laser Doppler vibrometry allows non-contact measurement of vibrations on the chest from respiration. Pyroelectric films can also detect temperature differences from breathing. The document provides examples of systems using these techniques and concludes that respiratory monitoring using pyroelectric films is cost-effective.

1. Department of Electronics and Instrumentation Technology
RVCE
A Seminar on
RESPIRATORY RATE MONITOR
By:
Goverdhan. R
1st sem, M.Tech
RVCE
Under the Guidance of
of
Dr. B.G Sudharshan
Associate Professor,
BMSPI, Dept. of E & IT Dept. of IT, R.V.C.E 03-12-2014 1

2. Contents
 Introduction
 Importance of monitoring respiratory rate
 Various method of measuring respiratory rate
 Respiratory rate measurement using Piezoelectric Sensor (PZO)
 Respiratory rate measurement from Laser Doppler Vibrometer
(LDVi)
 Respiration rate measurement system using Pyroelectric Sensor
 Impedance pneumography method
 Capnometry
 Respiratory rate measurement using PPG signal
 Conclusion
 References
BMSPI, Dept. of E & IT 03-12-2014 2

3. Introduction
 Respiration rate is an important vital sign. It is, the number of
breaths taken within a set amount of time.
 Tachypnea /Bradypnea / Apnoea, is a sensitive indicator of
physiologic distress that requires immediate clinical intervention.
Figure 1. Normal breathing rate [1]
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4. Importance of monitoring respiratory rate[2]
Figure 2: Causes of death (SOURCE: Sudden Cardiac
Arrest Foundation)
Tachyapnoea are an important predictor of cardiac arrest.(25-
27breaths/minute)
Mortality is high in Tachypnea persons.
BMSPI, Dept. of E & IT 03-12-2014 4

5. Various method of measuring respiratory rate
 Respiratory rate measurement using Piezoelectric Sensor (PZO).
 Respiratory rate measurement from Laser Doppler Vibrometer (LDVi).
 Respiration rate measurement System Using Pyroelectric Sensor.
 Impedance pneumography method.
 Capnometry.
 Respiratory rate measurement using PPG signal.
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6. Respiratory Rate measurement using Piezoelectric
Sensor (PZO)[3]
• Piezoelectric sensors have been used to detect breathing effects,
utilizing the piezoelectric property.
• It directly measures the electric potential changes produced when the
piezoelectric ceramic is impacted by respiratory airflow.
• piezoelectric film sensor made of aluminum nitride (AlN) material has
good sensitivity.
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7. Respiratory Rate using Piezoelectric Sensor
(PZO)[3](contd…)
Figure 3. Respiration belt Sleep Sense 1387-
kit.(Courtesy: www.biosemi.com) Figure 4. Piezoelectric output, periodogram
BMSPI, Dept. of E & IT 03-12-2014 7

8. Measurement of Respiratory Rate from Laser
Doppler Vibrometer (LDVi)[4]
 LDVi is a fully no-contact measurement method for monitoring of the
respiration rate.
 This method is operated at a distance of 3m, on different point of the
patient thoracic and abdominal area.
 Laser Doppler vibrometers can effectively detect vibration within two
hundred meters with a sensitivity on the order of 1 (mm/s)/V.
 The laser sensor works with a He–Ne laser source.
 No special safety precautions are required since laser power is less
than 1 mW.
BMSPI, Dept. of E & IT 03-12-2014 8

9. Measurement of Respiratory Rate from Laser
Doppler Vibrometer (LDVi)[4] (contd…)
Figure 6: Polytec OFV-505, an advanced laser
Vibrometer head, output signal.
Figure 5:Velocity BMSPI, Dept. of E & IT signal measured on the chest area 03-12-2014 9

10. Measurement of Respiration Rate in Preterm Infants
by Laser Doppler Vibrometry[5]
Figure 7: Setup of measurement. Figu0r3e-1 28-20:1 4scheme and procedure.
BMSPI, Dept. of E & IT
10

11. Respiration Rate Measurement System Using
Pyroelectric Transducer[6]
 A polyvinylidene fluoride (PVDF) has faster response time than
those of traditional thermal devices.
 A PVDF film has both piezoelectric and pyroelectric properties.
 The difference of temperature can be best sensed by using
PVDF placed in front of the nostrils by means of a suitable
holding device.
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12. Respiration Rate Monitoring Gauze Mask
System Using Pyroelectric Transducer[6]
Figure 9: Experiment setup Figure 10:Waveform derived from belt
system and experiment setup
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13. Impedance Pneumography Method[7]
 The objective of this technique is to measure changes in the
electrical impedance of the person’s thorax caused by respiration
or breathing.
 In both of these methods, a high-frequency ac current is injected
into the tissue through the drive electrodes.
 This potential difference is related to the resistivity of the tissue
between the voltage-sensing or receive electrodes.
 The equivalent resistance is defined as the ratio of the voltage
difference between the two receive electrodes and the current
that flows through the tissue.
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14. Impedance Pneumography Method[7]
BMSPI, Dept. of E & IT 03-12-2014 14
Figure 11: (A) Two Terminal measurement (B) Four Terminal Measurement (C) Simulator
output

15. Capnography
 The measurement is based on the absorption
property of infrared rays by certain gases (like
CO2, CO, and NO2).
 When infrared rays are passed through the
expired air containing a certain amount of CO2,
some of the radiations are absorbed by it.
 The detector changes the loss in heating effect of
the rays into an electrical signal.
Figure 12: Normal Capnogram
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16. Respiratory rate measurement using PPG
signal[8]
 Photoplethysmography(PPG) is the
measurement of blood volumetric
changes with each heartbeat.
 The PPG pulse obtained by the optical
sensor is used for various cardiovascular
parameter measurement.
 Frequency domain analysis of PPG signal
shows a two peaks first around 0.25 to
0.35Hz and second at around 1 to 1.5Hz.
Figure 13: Frequency spectrum of the PPG signal
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17. Respiratory rate measurement using PPG
signal[8]
Figure 14: System block diagram Figure 15: PPG of subject
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18. Conclusion
 Several techniques have been developed for the
measurement.
 The choice of a particular method depends upon the
ease of application of the transducer and their acceptance
by the subject under test.
 Respiratory rate monitor using PVDF is cost-effective.
BMSPI, Dept. of E & IT 03-12-2014 18

19. References
[1] Cretikos M, Bellomo R, Hillman K, Chen J, Finfer S, Flabouris A, “Respiratory Rate: the
neglected vital sign,” The Medical Journal of Australia Dec 2007.
[2] Ian Smith, John Mackay, Nahla Fahrid, Don Krucheck, “Respiratory rate measurement: a
comparison of methods,” British Journal of Healthcare Assistants, vol 05 No 01, January
2011.
[3] Bryson Padasdao, Olga Boric-Lubecke, “Respiratory Rate Detection Using a Wearable
Electromagnetic Generator ,“ International Conference of the IEEE EMBS Boston,
Massachusetts USA, August 30 - September 3, 2011.
[4] Zhigang Zhu, Ning Xiang, “Detecting Voice, Heart Beats and Respiration by a Laser Doppler
Vibrometer,” Online.
[5] Lorenzo Scalise, Ilaria Ercoli, Paolo Marchionni, Enrico Primo Tomasini, Measurement of
Respiration Rate in Preterm Infants by Laser Doppler Vibrometry,”IEEE,2011
BMSPI, Dept. of E & IT 03-12-2014 19

20. References
[6] Y. P. Huang, M. S. Young and K. N. Huang, “Respiratory Rate Monitoring Gauze Mask System
Based on a Pyroelectric Transducer,” IEEE, pp 1648-1649, 2008.
[7] Amit K. Gupta, “Respiration Rate Measurement Based on Impedance Pneumography,”
Application Report, Texas Instruments, 2011.
[8] Nivedita Daimiwal, M. Sundhararajan and Revati Shriram, “Respiratory Rate, Heart Rate and
Continuous Measurement of BP Using PPG,” International Conference on Communication and
Signal Processing, IEEE, pp 999-1002 April 2014.
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