A Room Temperature VOCs Gas Sensor Based on a Layer by Layer Multi-Walled Carbon Nanotubes/Poly-ethylene Glycol Composite.

Zitao Liu,Xiaohao Wang,Ying Dong,Tuoyu Yang

doi:10.3390/s18093113

Abstract

Sensitive detection of volatile organic compounds (VOCs) is significant for environmental monitoring and medical applications. In this work, multi-walled carbon nanotubes (MWCNTs) and polyethylene glycol (PEG) that have good adsorption for VOCs, were sprayed layer by layer on an interdigitated electrode (IDE) to build a sensitive VOCs gas sensor. The relative resistance change (△R/R) when the sensor was exposed to VOCs was measured. The sensor showed high sensitivity to acetone, ethanol, isopropanol and isoprene with fast response (110 ± 5 s) and recovery (152 ± 5 s) at room temperature, and the lower detection limit (LDL) of the sensor reached 9 ppm. With the micro-fabricated IDE structure, the sensor can be easily built into an electric nose for VOC recognition and measurement.

Highlights

The detection of volatile organic compounds (VOCs) in the environment or in exhaled breath has received considerable attention and is becoming increasingly important in the development of point of care testing (POCT) devices and Internet of Things (IoT) nodes [1,2,3,4,5,6,7]
(PEI) and polyethylene glycol (PEG), acetone, ethanol, isopropanol, isoprene and sodium dodecyl (PEI) and polyethylene glycol (PEG), acetone, ethanol, isopropanol, isoprene and sodium dodecyl sulfate (SDS) were purchased from Aladdin, Inc. (Shanghai, China) Morphological and structural sulfate (SDS) were purchased from Aladdin, Inc. (Shanghai, China) Morphological and structural characterization of the multi-walled carbon nanotubes (MWCNTs) were carried out using Field Emission Scanning Electron Microscopy characterization of the MWCNTs were carried out using Field Emission Scanning Electron (SU8010, FESEM, Tokyo, Japan) and a BX53M Upright Metallurgical Microscope (Olympus, Tokyo, Microscopy (SU8010, FESEM, Tokyo, Japan) and a BX53M Upright Metallurgical Microscope
A chemiresistive VOC sensor based on MWCNTs and PEG composite layers was designed and

Summary

Introduction

The detection of VOCs in the environment or in exhaled breath has received considerable attention and is becoming increasingly important in the development of point of care testing (POCT) devices and Internet of Things (IoT) nodes [1,2,3,4,5,6,7]. ZnO, SnO2 and WO3 -based gas sensors can detect several kinds of VOCs (e.g., isoprene, ethanol and acetone) at ppb levels [9,10,11] These sensors still exhibit limitations such as poor selectivity and high operating temperatures (typically within the 300 to 500 ◦ C range). This is because they are based on chemical oxidizing or reducing reactions between oxygen ions and the analyte, while VOCs have similar reducing reaction energies [12], and the high temperature is a necessary condition for generating oxygen ions. These disadvantages increase the power consumption and decrease the portability

Methods

Results

Conclusion