Sleep is an essential aspect of human health, occupying approximately one-third of our lives. However, studies indicate that around 3-7% of adults experience moderate to severe sleep apnea, a condition that disrupts sleep patterns and poses various risks such as daytime sleepiness, insomnia, and changes in behavior and sexual function. Consequently, the implementation of an apnea monitoring system is crucial. In this article, TechSparks aims to provide design guidelines for such a project to assist readers in addressing this issue effectively.
Understanding apnea provides ideas for projects
The diagnosis of sleep apnea in patients relies on the frequency of apnea and hypopnea events, with a threshold of ≥ 5 times per hour indicating a positive diagnosis.
- Apnea: Temporary cessation of breathing, either inhalation or exhalation, for more than ten seconds during sleep.
- Hypopnea: Partial reduction in airflow, where the airflow rate is less than 50% of normal, resulting in a drop in blood oxygen concentration of 4% or more.
In the medical field, professional nocturnal sleep apnea multi-physiological monitors are utilized to diagnose this condition. These monitors record various physiological parameters such as apnea, hypopnea, hypoxia index, electrocardiogram, and respiratory rate changes to provide accurate diagnostic results. While these monitors are the most authoritative detection equipment currently available, they tend to be complex due to the multiple measurements involved. Nocturnal sleep apnea polyphysiological monitors are typically used in hospitals or clinics and are operated by healthcare professionals. The aim of this guide, however, is to offer users an option for periodic and continuous testing through personal monitoring activities. Users can acquire testing equipment at an affordable price and perform measurements at home, thus ensuring accessibility. Therefore, the project should possess several key characteristics: simplicity of operation, affordability, and long-term monitoring capability.
Design of Wireless Sleep Apnea Monitoring
Project system design
Figure illustrates the system design diagram of the wireless sleep apnea monitoring project, encompassing three essential components:
- Measuring device: This component is responsible for capturing relevant physiological data such as respiration rate, oxygen saturation levels, and movement patterns during sleep.
- Recorder: The recorder receives and stores the data obtained from the measuring device. It ensures secure and reliable storage for subsequent analysis and review.
- Analyzer: The analyzer processes the recorded data to identify and analyze apnea and hypopnea events, as well as other relevant sleep metrics. It employs algorithms and signal processing techniques to extract valuable insights and generate reports for further examination.
These three interconnected components form a comprehensive system that enables wireless sleep apnea monitoring, facilitating accurate detection, recording, and analysis of sleep-related physiological parameters.
Block Architecture Design of Parameter Meter
The diagram illustrates the architecture of the wireless sleep apnea monitoring system, which comprises several circuit components, including the sensing circuit, single-chip microcontroller, serial memory, Bluetooth wireless module, real-time clock, charging circuit, and battery.
The sensing circuit is of particular significance as it is responsible for detecting and measuring various physiological indicators of the user during sleep. These indicators encompass metrics such as the frequency and duration of snoring events, the number and duration of apnea episodes, blood oxygen saturation levels, airflow in the nasal and oral cavities, and heart rate changes.
During the design of the single-chip microcontroller, it is essential to develop software that records the different physiological parameters based on a time axis. Each data point is stored in the memory and transmitted through the Bluetooth module. This data recording and transmission process enables the reconstruction of the sleep-related information, allowing for the analysis and understanding of the interrelationships between the various physiological parameters.
Design of Apnea Detection Recorder
The software embedded within the single-chip microcontroller assumes the crucial role of managing the connection and data transfer operations of the Bluetooth module. It also undertakes the task of converting the diverse physiological parameters related to sleep breathing into a serialized time-voltage digital format, which is subsequently stored in the flash memory for secure retention.
Furthermore, an application software suite has been developed utilizing Microsoft Visual BASIC to cater to the needs of the wireless sleep breathing multi-physiological parameter recorder and analyzer. This software suite offers a comprehensive display of the acquired sleep breathing data, encompassing various physiological parameters. With a user-friendly interface, it facilitates intuitive interaction and effectively presents the patient’s sleep patterns and fluctuations in an easily understandable visual format.
Sleep Apnea Monitoring System Design Guidelines
When designing the software for the single-chip microcontroller, it is essential to measure various physiological parameters based on a time axis and establish their relationships during data reconstruction. To ensure accurate transmission of data through the Bluetooth module, a serial memory is utilized to temporarily store the measurement information, mitigating the risk of data loss. The wireless sleep breathing multi-physiological parameter measuring instrument is designed for compactness, emphasizing low power consumption and small component selection. The integration of a single-chip microcontroller optimizes overall power consumption. The Bluetooth wireless module is chosen for its low power consumption and high security, enabling wireless data transmission.
During physiological parameter measurements, proper fixation of the measuring device on the patient’s body is crucial. Head and body movements during sleep can cause the device to detach or yield incorrect measurements, potentially affecting the assessment of symptoms by medical professionals. Therefore, the wireless meter’s sensor needs to be small, securely attached, and non-disruptive to the patient’s sleep. Data processing involves applying band-pass filters to eliminate irrelevant data, presenting only the authentic waveforms of multiple physiological parameters related to sleep breathing, thereby enhancing diagnostic accuracy.
Furthermore, the wireless sleep apnea multi-physiological parameter meter and recorder are designed to be portable devices, necessitating efficient power management. The single-chip microcontroller is responsible for power control, achieving reduced power consumption by operating at a lower frequency. Sleep mode is utilized to conserve power without compromising accuracy. The digital sampling frequency of data is lowered, reducing the data volume and temporarily storing it in the serial memory. The Bluetooth wireless module remains in sleep mode until the serial memory is nearly full, at which point it is activated to establish a connection with the sleep breathing multi-physiological parameter recorder, thereby minimizing power consumption of the wireless measuring instrument.