Noninvasive analysis of exhaled breath for gastric cancer diagnosis using paper-based smartphone nano-optoelectronic noses

A paper-based colorimetric sensor array with an integrated smartphone was developed to detect a wide range of volatile organic compounds (VOCs) and used for an exhaled-breath analysis of VOCs associated with gastric cancer (GC). The sensor array combines functionalized nanoplasmonic materials and chemically responsive organic dyes which change color when they come in chemical contact with VOCs. Parts per billion (ppb)-level detection is achieved based on color changes of the array. Gas chromatography-mass spectroscopy (GC-MS) analysis of the exhaled gas from GC patients and healthy candidates indicated 25 different VOCs which may be used as the biomarkers. The paper-based smartphone nano-optoelectronic nose, used in combination with orthogonal partial least squares discriminant analysis (OPLS-DA), was able to differentiate between VOCs associated with GC patients and healthy candidates with an accuracy of 90 %. This cost-effective sensor platform paves a way for further clinical breath analysis on the noninvasive screening of GC and potentially other gas detection in medical diagnosis and environmental monitoring.