Respiratory rate monitoring system based on inorganic halide perovskite humidity sensor

Wu Yingjie; Wu Zhilin; Wang Lin; Nian Weiqi; He Yong; Guo Yongcai

doi:10.12086/oee.2021.200100

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Wu Y J, Wu Z L, Wang L, et al. Respiratory rate monitoring system based on inorganic halide perovskite humidity sensor[J]. Opto-Electron Eng, 2021, 48(3): 200100. doi: 10.12086/oee.2021.200100

Citation:

Wu Y J, Wu Z L, Wang L, et al. Respiratory rate monitoring system based on inorganic halide perovskite humidity sensor[J]. Opto-Electron Eng, 2021, 48(3): 200100. doi: 10.12086/oee.2021.200100

Respiratory rate monitoring system based on inorganic halide perovskite humidity sensor

1.
Key Laboratory of Optoelectronic Technology and Systems of Ministry of Education of China, Chongqing University, Chongqing 400044, China
2.
Chongqing University Cancer Hospital, Chongqing 400030, China

Fund Project: 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)

More Information

Corresponding author: Guo Yongcai, E-mail: ycguo@cqu.edu.cn

Received Date 23 March 2020

Revised Date 06 November 2020

Published Date 15 March 2021

Abstract

Abstract

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 10~12 breaths/min (1 ventilation every 5~6 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 airflow /
- humidity sensor /
- respiratory rate monitoring /
- wireless communication /
- upper computer design

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References

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Overview

Overview

Overview: Respiratory rate, as an important parameter of respiratory function, refers to the number of breaths per minute, and can provide important information related to health status. Continuously, accurately and stably monitoring respiratory rate is great significance for preventing respiratory diseases, cardiovascular diseases. It is simple and accurate to measure breathing rate by measuring the respiratory airflow. However, common airflow detecting methods, such as temperature sensors, piezoelectric sensors, and flow sensors, having weak output signals. There is 30% humidity difference between human exhaled gas with the outside world, humidity sensor can be used to measure the breathing signal. Human breathing frequency from 12 to 20 times per minute. The response and recovery time of the humidity sensors on the market range from ten seconds to tens of seconds, which cannot use to respiratory rate monitoring. When 30% humidity change occurs in the inorganic halide perovskite humidity sensor made in this paper, resistance will change significantly and recover within 3 seconds, which can be used to measure respiratory nasal airflow signals.

For the convenience of testers, this system uses Zigbee wireless network to transmit signals. The system is divided into four parts: sensor, data acquisition and sending node, receiving node, and host computer software. The data acquiring and sending node collects breathing signal converted by the humidity sensor and sends it to receiving node. Receiving node transmits received data to host computer software. The host computer software processes the received data, and compute respiratory rate through the algorithm. After processing, the relevant information is displayed on the interface for reference by medical staff. From the test data of five testers, it can be seen that under fast, slow, and normal breathing, the maximum error between the system test breathing rate and the tester's actual breathing rate is 1 per minute, and the system can accurately monitor the breathing rate.

This article designs and develops a respiratory rate monitoring system based on an inorganic halide perovskite humidity sensor, which can accurately measure the breathing process through respiratory airflow. It has a simple structure, a large output signal, a fast response speed, low energy consumption, and is easy to carry. The advantage is that the system's measured breathing results have high accuracy and good circulation stability. The system is expected to be applied in many scenarios such as daily respiratory rate measurement and monitoring of patient respiratory rate in hospitals.