Smartphone-Based pH Sensor for Home Monitoring of Pulmonary Exacerbations in Cystic Fibrosis.

Alexander Sun,Chengyang Yao,Douglas Conrad,Drew Hall,A Venkatesh,Tom Phelps

doi:10.3390/s17061245

Alexander Sun, Chengyang Yao + Show 4 more

Open Access

https://doi.org/10.3390/s17061245

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Abstract

Currently, Cystic Fibrosis (CF) patients lack the ability to track their lung health at home, relying instead on doctor checkups leading to delayed treatment and lung damage. By leveraging the ubiquity of the smartphone to lower costs and increase portability, a smartphone-based peripheral pH measurement device was designed to attach directly to the headphone port to harvest power and communicate with a smartphone application. This platform was tested using prepared pH buffers and sputum samples from CF patients. The system matches within ~0.03 pH of a benchtop pH meter while fully powering itself and communicating with a Samsung Galaxy S3 smartphone paired with either a glass or Iridium Oxide (IrOx) electrode. The IrOx electrodes were found to have 25% higher sensitivity than the glass probes at the expense of larger drift and matrix sensitivity that can be addressed with proper calibration. The smartphone-based platform has been demonstrated as a portable replacement for laboratory pH meters, and supports both highly robust glass probes and the sensitive and miniature IrOx electrodes with calibration. This tool can enable more frequent pH sputum tracking for CF patients to help detect the onset of pulmonary exacerbation to provide timely and appropriate treatment before serious damage occurs.

Highlights

Cystic Fibrosis (CF) is an inherited chronic disease that adversely affects the lungs and digestive systems of about 30,000 children and adults in the United States, as well as approximately 70,000 people worldwide [1]
Due to the abnormally viscous secretions in their lungs and pancreas that lead to inflammation and organ damage, CF patients often suffer from chronic lung disease, lung infection, bronchiectasis, and malnutrition [2]
When using the glass electrode, the smartphone-based pH platform matches within ~0.03 pH of the benchtop pH meter over the timespan of a week without daily recalibration. Does this show that the smartphone-based tool matches well with the benchtop meter, and it suggests that, when using glass probes, frequent or full calibration is not required

Summary

Introduction

Cystic Fibrosis (CF) is an inherited chronic disease that adversely affects the lungs and digestive systems of about 30,000 children and adults in the United States, as well as approximately 70,000 people worldwide [1]. People living with this lifelong disease must follow a regular treatment routine to stay healthy and maintain optimal lung function, requiring frequent physician visits to test and clear airway infections. Current tools, such as clinical culturing, take days to obtain results, and are not able to detect whether a patient is undergoing an exacerbation, leaving physicians to make choices about antibiotic treatment based on trial and error. Recent studies have shown that a decrease in pH of exhaled breath condensate, as well as increase in fermentation products and upregulation of Sensors 2017, 17, 1245; doi:10.3390/s17061245 www.mdpi.com/journal/sensors

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