Chemiresistive Electronic Nose toward Detection of Biomarkers in Exhaled Breath

Abstract

Detection of gas-phase chemicals finds a wide variety of applications, including food and beverages, fragrances, environmental monitoring, chemical and biochemical processing, medical diagnostics, and transportation. One approach for these tasks is to use arrays of highly sensitive and selective sensors as an electronic nose. Here, we present a high performance chemiresistive electronic nose (CEN) based on an array of metal oxide thin films, metal-catalyzed thin films, and nanostructured thin films. The gas sensing properties of the CEN show enhanced sensitive detection of H2S, NH3, and NO in an 80% relative humidity (RH) atmosphere similar to the composition of exhaled breath. The detection limits of the sensor elements we fabricated are in the following ranges: 534 ppt to 2.87 ppb for H2S, 4.45 to 42.29 ppb for NH3, and 206 ppt to 2.06 ppb for NO. The enhanced sensitivity is attributed to the spillover effect by Au nanoparticles and the high porosity of villi-like nanostructures, providing a large surface-to-volume ratio. The remarkable selectivity based on the collection of sensor responses manifests itself in the principal component analysis (PCA). The excellent sensing performance indicates that the CEN can detect the biomarkers of H2S, NH3, and NO in exhaled breath and even distinguish them clearly in the PCA. Our results show high potential of the CEN as an inexpensive and noninvasive diagnostic tool for halitosis, kidney disorder, and asthma.

A Highly Stable Two‐Dimensional Copper(II) Organic Framework for Proton Conduction and Ammonia Impedance Sensing

“…At the same time, the ammonia contento fe xhaled breath is an important biomarker for diagnosing halitosis, stomach cancer,a nd kidney disorders. [30,31] Accordingly,t om onitor the concentrationo ft race ammonia in air or exhaled breath is an important issue fore nvironmental protection and medical monitoring.…”

Influence of Water Molecules on the Detection of Volatile Organic Compounds (VOC) Cancer Biomarkers by Nanocomposite Quantum Resistive Vapor Sensors vQRS

“…In order to investigate these different aspects, expected to govern the characteristics of the chemo-resistive response of polymer nanocomposite based vQRS, they have been exposed to mixtures of water vapor and VOC mixed in various proportions. Moreover to get closer to the composition of real breath, i. e., only few ppm of VOC were dispersed in thousand ppm of water molecules [57].…”

Highly Sensitive Sensors Based on Metal-Oxide Nanocolumns for Fire Detection

“…Further, it is well known that highly ordered one-dimensional nanostructures, which show extremely large surface-to-volume ratios, are the most promising material platform for a good gas-sensing performance due to the excellent accessibility of target gases and aggregation-free geometry [19]. Accordingly, our previous studies have investigated the gas-sensing properties of metal-oxide gas sensors based on one-dimensional nanostructures, and already demonstrated their high sensing performance in response to various gases, including C 2 H 5 OH, NO 2 , SO 2 , H 2 , C 7 H 8 , CH 4 , CH 3 COCH 3 , C 6 H 6 , NH 3 , H 2 S, and C 6 H 6 compared with plain films [23,27,28,29]. However, despite their decent gas-sensing properties, the selectivity of gas sensors based on metal oxides has remained challenging.…”