Mobile Phone-based Pulse Oximeter

Researcher: Drew Hall (UC San Diego)
Location: United States

Millions worldwide suffer from diseases that exhibit early warnings signs that can be detected by standard clinical-grade diagnostic tools. Unfortunately, such tools are often prohibitively expensive to the developing world, leading to inadequate healthcare and high mortality rates.

To address this problem, a smartphone-based pulse oximeter was developed that interfaces with the phone through the audio jack, enabling point-of-care measurements of heart rate (HR) and oxygen saturation (SpO2). The device is designed to utilize existing phone resources (such as the processor, battery, and memory) resulting in a more portable and inexpensive diagnostic tool than standalone equivalents. By adaptively tuning the LED driving signal, the device is less dependent on phone-specific audio jack properties than prior audio jack-based work, making it universally compatible with all smartphones.

Results

Previous funding from PDEL supported development of a smartphone-based pulse oximeter for use in low- to middle-income countries where access to clinical grade diagnostic tools is limited. At the time, only an Android version of the software was available, and it supported a limited number of mobile phones.

This phase of the project focused on validating the device’s performance and comparing it against a clinical grade instrument. Heart rate variabilitywas added to the device as well.

Results demonstrate that the pulse oximeter is capable of performing well using several types of smartphones. Results compared well to the iOximeter (a commercial grade instrument used in clinics worldwide), making it a low-cost and accurate alternative. 

Researchers have developed Android and iOS versions of the app, the source code of which will be made publicly available on Github, and greatly expanded the number of phones that it can support thanks to a new signal-noise-ratio (SNR) versus power adaptive algorithm developed by the researchers.

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