Nanoassembled Thin-film-coated Quartz Crystal Microbalance Odor Sensors for Environmental and Human Breath Ammonia Assessments

Kenshi Hayashi ,Shunichi Wakamatsu ,Seung Woo Lee ,Roman Selyanchyn

doi:10.18494/sam.2018.1734

Kenshi Hayashi , Shunichi Wakamatsu + Show 2 more

Open Access

https://doi.org/10.18494/sam.2018.1734

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Abstract

Nanoassembled Thin-film-coated Quartz Crystal Microbalance Odor Sensors for Environmental and Human Breath Ammonia Assessments

Highlights

Odors are generally determined by the combination of volatile organic and inorganic compounds that have a high vapor pressure even at ordinary room temperature, and are identified and described by humans’ natural sense of smell
In our initial approach to gas sensing, TiO2 ultrathin films that were alternately assembled with layers of poly(acrylic acid) (PAA) by the surface sol–gel process were used for ammonia detection.[17]. We have reported the creation of reliable quartz crystal microbalance (QCM) humidity sensors modified with porphyrin-based nanothin films,(21) which could be applied to daily needs, for instance, the monitoring of indoor environmental quality.[22]. Recently, we have reported a respiration assessment system, based on QCM electrodes, which possessed a surface modified with nanoassembled thin films.[23,24] We were able to obtain an online breathing record owing to the quick response of the QCM sensors to the fast changes in relative humidity (RH) in human breath samples
For the development of a gas sensor system for real environment measurements from several sources, we examined the LbL deposition of porphyrin/polymer thin films on the surface of 9 MHz QCM electrodes.[22]. RH was selected because it is a highly important factor for human comfort and well-being inside buildings,(21) ammonia was chosen to test the system as one of the most important analytes for indoor air quality (IAQ) assessment,(29) and cigarette smoke was chosen because it is the simplest environmental factor that significantly influences IAQ

Summary

Introduction

Odors are generally determined by the combination of volatile organic and inorganic compounds that have a high vapor pressure even at ordinary room temperature, and are identified and described by humans’ natural sense of smell. In our initial approach to gas sensing, TiO2 ultrathin films that were alternately assembled with layers of poly(acrylic acid) (PAA) by the surface sol–gel process were used for ammonia detection.[17] We have reported the creation of reliable QCM humidity sensors modified with porphyrin-based nanothin films,(21) which could be applied to daily needs, for instance, the monitoring of indoor environmental quality.[22] Recently, we have reported a respiration assessment system, based on QCM electrodes, which possessed a surface modified with nanoassembled thin films.[23,24] We were able to obtain an online breathing record (respiratory pattern) owing to the quick response of the QCM sensors to the fast changes in relative humidity (RH) in human breath samples. The proposed system, with all the necessary built-in units, can be used to access mechanical parameters and the chemical composition of environmental and human samples

Real Environment Measurements

Ammonia Detection in Human Breath

Channel oscillation generator

Conclusions