Chemical sensors integrated with mobile phones for remote medical diagnostics: state-of-the-art and beyond

Abstract

Human breath and sweat are sources of biogenic volatile organic compounds (VOCs) which can be sampled noninvasively providing medical information. Smartphones can be equipped with a variety of classical sensors (e.g. camera, audio, temperature/humidity, geomagnetic, proximity, barometer, accelerometer, GPS, gyroscope, etc.) but also with chemical sensors for gases and VOCs monitoring and then be used as personalized health monitoring devices. The goal of this paper is to highlight the latest research efforts towards the direction of transforming smartphones to revolutionary diagnostic medical tools, being able to detect and process chemical profiles related to vital signs but also with the potential to therapeutic monitoring.

A Linear-Quadratic Model for the Quantification of a Mixture of Two Diluted Gases with a Single Metal Oxide Sensor

“…The aim of this work is to quantify a mixture of two gases diluted in an air buffer (79% of nitrogen and 21% of oxygen), with only a single sensor. Acetone is one of the VOCs with the highest concentration in exhaled breath air [ 23 ]. It is also linked to several clinical applications, such as diabetes or weight loss monitoring.…”

“…In such applications, it is known that acetone might interfere in the evaluation of alcohol concentration [ 24 ]. Thus, a mixture of acetone and ethanol diluted in air is a relevant model of exhaled breath air to test the analysis of the most abundant VOCs [ 23 ]. This ethanol interfering gas would simulate all the others gases present in breath.…”

Addressing challenges in using breath chemical analysis in smartphone-based health diagnostics

“…A number of sophisticated analytical techniques (e.g. GC-MS, GC-MS/MS, HPLC-MS, SRI-TOF-MS, IMS) have been involved to recognize and define the disease-specific chemical fingerprints [1]. Unfortunately, the analytical instruments provided by these techniques are inherently bulky, expensive, demand laborious and time-consuming sample-preparation methods, and require welltrained and experienced operators.…”

“…Specific VOCs in breath are product of metabolic processes and are closely linked with medical information. The concept of using chemical breath analysis in combination with mobile phones for remote medical diagnostics is quite challenging [1,2]. The detection of VOCs in breath can be related to diagnosis and monitoring of diseases and metabolic disorders such as cancer, diabetes, asthma and liver or renal failure.…”