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[[Vol. 35]Environmental Monitoring of Air Pollution_ тАШDetect to WarnтАЩ Sensing System for Monitoring Formaldehyde_ WPI-MANA.pdf](https://mdr.nims.go.jp/filesets/48f21336-1de8-4645-a5d1-25fd8848c098/download)

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International Center for Materials Nanoarchitectonics (WPI-MANA)

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[[Research Highlights Vol.35] Environmental Monitoring of Air Pollution: ‘Detect to Warn’ Sensing System for Monitoring Formaldehyde](https://mdr.nims.go.jp/datasets/a9b3857b-003a-4cc6-a5a1-ff493a11eceb)

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2022/04/04 10:08 Environmental Monitoring of Air Pollution: ‘Detect to Warn’ Sensing System for Monitoring Formaldehyde| MANAhttps://www.nims.go.jp/mana/research/highlights/vol35.html 1/3Previous  Index  NextResearch Highlights[Vol. 35]Environmental Monitoring of Air Pollution: ‘Detect to Warn’ Sensing System forMonitoring Formaldehyde27 Mar, 2018Compact ‘referenced—chemiresistive-sensors’ consisting of network-assembly ofsemiconducting carbon nanotubes and hydroxylamine hydrochloride enable highlyselective and continuous measurement of formaldehyde for environmental monitoring.Figure: Reference and sensing devices are visualized using LEDs. The presence offormaldehyde is shown by the brighter LED.Formaldehyde (HCHO) and related chemical compounds used in the construction industry toprevent decay of building materials are known to cause dermatitis, asthma, and other suchailments. Such health issues related indoor air pollution–referred to as ‘sick building syndrome’–is aglobal problem with World Health Organization (WHO) guidelines recommending a maximumpermissible concentration of HCHO of 0.08 ppm indoors. But monitoring levels of HCHO is nottrivial, with conventional technology being expensive, bulky, and although compact monitoringsystems exist, they require renewal of ‘detection tags’ after each measurement, and have issuesrelated to continuous and long term monitoring.Here, Shinsuke Ishihara and colleagues at the WPI-MANA, National Institute for Materials Sciencein Tsukuba and collaborators at the Nanomaterials Research Institute, National Institute ofAdvanced Industrial Science and Technology (AIST), Tsukuba, report on the development of aninnovative HCHO detection system based on a combination of hydroxylamine hydrochloride andhttps://www.nims.go.jp/mana/research/highlights/vol34.htmlhttps://www.nims.go.jp/mana/research/highlights/index.htmlhttps://www.nims.go.jp/mana/research/highlights/vol36.html2022/04/04 10:08 Environmental Monitoring of Air Pollution: ‘Detect to Warn’ Sensing System for Monitoring Formaldehyde| MANAhttps://www.nims.go.jp/mana/research/highlights/vol35.html 2/3network-assembly of semiconducting single walled carbon nanotube (SWCNTs) sensors capable ofhighly selective and continuous monitoring. Specifically, the SWCNT sensor is reusable; has adetection limit of 0.016 ppm; HCHO-selectivity of 105 to 106 times higher than other vapors suchas water and methanol; and the implementation of a reference sensor adjacent to an active oneprevents false positives.The reaction of HCHO with hydroxylamine hydrochloride generates hydrochloric acid, which causeschanges in the conductivity of the SWCNTs that are measured with an external electrical circuit.The reference sensor does not have hydroxylamine hydrochloride present at its surface, hence thesensor does not react to HCHO.“The high performance and versatility of our sensors was achieved by designing devices withprecise separation of semiconducting carbon nanotubes, monodisperse treatment of carbonnanotubes and improvement of active surface area by networking,” says Ishihara. “Furthermore,our sensor is low cost, portable, and long lifetime, thereby making it suitable as a ‘detect to warn’sensory system.”Reference“Amperometric Detection of Sub-ppm Formaldehyde Using SingleWalled Carbon Nanotubes andHydroxylamines”Shinsuke Ishihara[1], Jan Labuta[1], Takashi Nakanishi[1], Takeshi Tanaka[2], and HiromichiKataura[2]Journal : A Referenced Chemiresistive System. ACS Sens. 2, 1405–1409, (2017).DOI : 10.1021/acssensors.7b00591(This paper is also highlighted by ACS Select Virtual Issue: Advances in ElectroanalyticalChemistry; see J. Am. Chem. Soc. 140, 2701–2703, (2018))Affiliations[1] World Premier International Center for Materials Nanoarchitectonics (WPI-MANA), NationalInstitute for Materials Science, (NIMS), Tsukuba, Ibaraki 305-0044, Japan[2] Nanomaterials Research Institute, National Institute of Advanced Industrial Science andTechnology (AIST), Tsukuba, Ibaraki, 305-8565, JapanContact informationInternational Center for Materials Nanoarchitectonics(WPI-MANA)National Institute for Materials Science1-1 Namiki, Tsukuba, Ibaraki 305-0044 JapanPhone: +81-29-860-4710E-mail: mana-pr[AT]ml.nims.go.jphttps://samurai.nims.go.jp/profiles/ishihara_shinsuke?locale=enhttps://samurai.nims.go.jp/profiles/labuta_jan?locale=enhttps://samurai.nims.go.jp/profiles/nakanishi_takashi?locale=enhttps://pubs.acs.org/doi/abs/10.1021%2Facssensors.7b00591https://pubs.acs.org/page/jacsat/vi/advances-in-electroanalytical?ref=feature2022/04/04 10:08 Environmental Monitoring of Air Pollution: ‘Detect to Warn’ Sensing System for Monitoring Formaldehyde| MANAhttps://www.nims.go.jp/mana/research/highlights/vol35.html 3/3