The traditional respiratory rate measurement technologies have several deficiencies, such as subjective appraised results, complicated signal extraction processes, difficult access to equipment, and inconvenience to move due to the wired connection setting. The respiratory airflow can directly reflect the human breath, and the respiratory frequency is usually 1012 breaths/min (1 ventilation every 56 seconds). The humidity difference between exhalation and inhalation can be directly used to measure respiratory rate. In the present work, a wireless respiratory rate monitoring system based on inorganic halide perovskite humidity sensor was developed. The sensor exhibits an ultrasensitive humidity sensing performance, which overcomes the long response/recovery time (> 10 seconds) of the commercial humidity sensors. The system utilized a Zigbee wireless communication to transmit the measurement signal, which separates the signal detection and processing parts, making it easier for the tester to move. The upper computer software was designed and used for data processing to calculate the breathing rate. The system can accurately monitor the respiratory rate in real-time, recognize and alarm the apnea successfully by comparing with a setting threshold value. The test results show that the system can accurately monitor the breathing rate with a maximum error of 1 time per minute. The system possesses great potential for application in respiratory rate monitoring due to its high accuracy, simple operation, portability, and low cost.
Respiratory rate monitoring system based on inorganic halide perovskite humidity sensor
First published at:Mar 22, 2021
 Cretikos M A, Bellomo R, Hillman K, et al. Respiratory rate: the neglected vital sign[J]. Med J Aust, 2008, 188(11): 657–659.
 Allen J. Photoplethysmography and its application in clinical physiological measurement[J]. Physiol Meas, 2007, 28(3): R1–R39.
 Hogan J. Why don't nurses monitor the respiratory rates of patients?[J]. Br J Nurs, 2006, 15(9): 489–492.
 Chen X C, Zhao H, Bi Y G, et al. Respiratory rate estimation from smartphone-camera-acquired pulse wave signal using visible light[J]. J Northeast Univ (Nat Sci), 2017, 38(7): 932–935.
陈星池, 赵海, 毕远国, 等. 手机可见光提取脉搏中呼吸率的估计[J]. 东北大学学报(自然科学版), 2017, 38(7): 932–935.
 Pimentel M A F, Johnson A E W, Charlton P H, et al. Toward a robust estimation of respiratory rate from pulse oximeters[J]. IEEE Trans Biomed Eng, 2017, 64(8): 1914–1923.
 Chen X C, Zhao H, Li H, et al. Detection of respiratory rate using pulse wave on near infrared wearable devices[J]. Opt Precision Eng, 2016, 24(6): 1297–1306.
陈星池, 赵海, 李晗, 等. 近红外可穿戴设备中脉搏波的呼吸率检测[J]. 光学 精密工程, 2016, 24(6): 1297–1306.
 Charlton P H, Birrenkott D A, Bonnici T, et al. Breathing rate estimation from the electrocardiogram and photoplethysmogram: a review[J]. IEEE Rev Biomed Eng, 2018, 11: 2–20.
 Chu T S, Lu M Z, Ma Z X. Respiratory rate measurement based on mattress life monitor[J]. Technol Innov Appl, 2014(18): 5–6.
储泰山, 陆美珠, 马志新. 基于床垫式生命监测仪的呼吸率检测[J]. 科技创新与应用, 2014(18): 5–6.
 Turnbull H, Kasereka M C, Amirav I, et al. Development of a novel device for objective respiratory rate measurement in low-resource settings[J]. BMJ Innovat, 2018, 4(4): 185.
 Lee P J. Clinical evaluation of a novel respiratory rate monitor[J]. J Clin Monit Comp, 2016, 30(2): 175–183.
 Fan D Y. Improved design and algorithm research of portable respiratory detection system[D]. Tianjin: Tianjin University, 2018.
范大勇. 便携式呼吸监测系统设计方案的改进和算法研究[D]. 天津: 天津大学, 2018.
 Zhen Z, Li Z C, Zhao X L, et al. Formation of uniform water microdroplets on wrinkled graphene for ultrafast humidity sensing[J]. Small, 2018, 14(15): 1703848.
 Smith A D, Elgammal K, Niklaus F, et al. Resistive graphene humidity sensors with rapid and direct electrical readout[J]. Nanoscale, 2015, 7(45): 19099–19109.
 Atalay O, Kennon W R, Demirok E. Weft-knitted strain sensor for monitoring respiratory rate and its electro-mechanical modeling[J]. IEEE Sens J, 2015, 15(1): 110–122.
 Zheng Y L, Ding X R, Poon C C Y, et al. Unobtrusive sensing and wearable devices for health informatics[J]. IEEE Trans Biomed Eng, 2014, 61(5): 1538–1554.
 Mogera U, Sagade A A, George S J, et al. Ultrafast response humidity sensor using supramolecular nanofibre and its application in monitoring breath humidity and flow[J]. Sci Rep, 2014, 4: 4103.
 Borini S, White R, Wei D, et al. Ultrafast graphene oxide humidity sensors[J]. ACS Nano, 2013, 7(12): 11166–11173.
 Adib F, Mao H Z, Kabelac Z E, et al. Smart homes that monitor breathing and heart rate[C]//Proceedings of the 33rd Annual ACM Conference on Human Factors in Computing Systems, South Korea, 2015: 837–846.
 Iber C, Ancoli-Israel S, Chesson A L, et al. The AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology and Technical Specifications[M]. 2nd ed. Westchester, Ill, USA: American Academy of Sleep Medicine, 2012.
 Anichini C, Aliprandi A, Gali S M, et al. Ultrafast and highly sensitive chemically functionalized graphene oxide-based humidity sensors: harnessing device performances via the supramolecular approach[J]. ACS Appl Mater Interfaces, 2020, 12(39): 44017–44025.
National Key R & D Plan for Major Instruments (2016YFF0102802), Chongqing Key Instrument Project (cstc2017zdcy-zdzxX0009), Funded by Special Fund for Performance Incentive Guidance of Scientific Research Institutions in Chongqing (cstc2019jxjl130029), Chongqing Natural Science Foundation (cstc2018jcyjA3233, cstc2019jcyj- msxmX0623), Fundamental Scientific Research Business of Central Universities (2018CDQYGD0008, 2018CDXYGD0017, 2019CDQYGD004), and Chongqing Graduate Research and Innovation Project (CYS19011)
Get Citation: Wu Yingjie, Wu Zhilin, Wang Lin, et al. Respiratory rate monitoring system based on inorganic halide perovskite humidity sensor[J]. Opto-Electronic Engineering, 2021, 48(3): 200100.