以MP3錄音機製作可攜式血氧濃度長時間記錄器

A portable long term recorder for oxygen saturation using MP3 recorder

王俊傑(Chun-Chieh Wang)

指導教授 ： 蔡正倫

中原大學/工學院/醫學工程研究所/碩士(2007年)

https://doi.org/10.6840/CYCU.2007.00659

摘要

本研究目的是發展低價格且能長時間記錄光體積描記圖和血氧濃度的記錄器。此記錄器是利用具有轉檔錄音功能的市售MP3數位錄音機來將所記錄的光體積變化描述圖壓縮成MP3檔案格式。光體積變化描記圖訊號以350Hz的頻率取樣記錄後再傳送到電腦進行訊號的處理分析。由於可攜式數位錄音機通常使用低電壓的電池來提供電力，因此不用顧慮使用時的電安全問題。這種安全且便宜的生理訊號記錄器將方便人們經常性地記錄與檢查自己的生理狀況，並且有助於提早偵測出心血管系統的問題。MP3錄音機只要內建有1 GB的快閃記憶體，就可以記錄超過10小時的訊號，因此真正可記錄的時間長度是受限於電池的所能提供電力的時間長度。
文獻報告曾指出在運動後的心率恢復速率可以做為評估心血管系統狀況的有用指標，也就是在運動停止後的第一分鐘內心率恢復如果低於12次，將來會有較高死亡率。MP3錄音機所使用的16位元類比/數位轉換器，因為具有非常高的訊號解析度和非常大的動態範圍，加上所使用的快閃記憶體錄音機兼具有體積小和重量輕的優點，因此方便在運動時隨身攜帶在身上，隨時記錄心率與血氧濃度的起伏變化情形。雖然心率和血氧濃度不能在記錄過程中立即顯示在記錄器上，但這反而可使量測結果更為客觀。將所記錄分析的心率和血氧濃度與市售的醫療儀器進行比較測試的結果顯示，兩者之間血氧濃度值的差異小於2％，而心率值和變化趨勢則幾乎完全一致。

關鍵字

心率恢復 ； 血氧濃度 ； MP3數位錄音機 ； 光體積變化描記圖

並列摘要

The purpose of this study is to develop a low cost long term digital recorder for photoplethysmograph and pulse oxygen saturation signals. The recorder is based on a commercial MP3 digital recorder with line-in input, and the photoplethysmograph signal is recorded as a compressed MP3 file. The photoplethysmograph signal is sampled at 350 Hz and transferred to a personal computer for signal processing and analysis. The portable recorder is generally powered by a low voltage battery. Therefore, there is no concern of electrical safety. Such a safe and affordable physiological signal recorder will allow people to self check their body condition more frequently. It is also helpful to early detect some cardiovascular system disorders. Since an MP3 recorder with 1 Giga Bytes of flash memory can store more than 10 hours of signal, the recording time is only limited by the capacity of battery.
The 16 bits analog-to-digital converter used in an MP3 recorder has a very high signal resolution and a very large dynamic range. The flash memory recorder is also small in size and light in weight. Therefore, it is highly portable and can be carried while doing exercise. The heart rate recovery after severe exercise has been reported as a useful index of the condition of cardiovascular system. If the recovery rate within the first minute were less than 12 beats, it might indicate a higher mortality rate in the future. This recorder allows the measurement of heart rate recovery signal to be recorded in the field. Although heart rate and oxygen saturation can not be shown on the recorder for reading, this actually makes the measurement more objective. The measurement of heart rate and oxygen saturation were compared with those of a commercial medical device. The difference in oxygen saturation reading between two measurements was less than 2%, and the heart rate readings and trends were also almost identical.

並列關鍵字

photoplethysmograph ； MP3 digital recorder ； heart rate recover ； oxygen saturation

參考文獻

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