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Scientific Reports on Micro and Nanosystems

edited by Christofer Hierold

Vol. 35

Stefan Nedelcu

Energy efficient analog mixed-signal front ends

for CNT-FET NO₂ air-quality nanosensors

1^stEdition 2022. XXVIII, 236 pages. € 64,00.
ISBN 978-3-86628-779-2

Abstract

Alongside climate change, air pollution is one of the most concerning public

health topics of the 21st century. Statistics estimate that more than seven

million people die from air pollution yearly, especially in low- and middleincome

countries, where people suffer from the highest exposure. Inhalable

micrometer particulate matter (PM2:5 and PM10), nitrogen dioxide (NO2),

ozone (O3), sulfur dioxide (SO2), and carbon monoxide (CO) are the most

common pollutants, permanently monitored by World Health Organization

(WHO). The six pollutants mentioned above are the main causes of a few

million premature deaths annually and NO2 is one of the most important

pollutants in the eye of public health. WHO’s new guidelines recommend

an NO2 average level that should not exceed 107 ppb hourly, and 5 ppb annually.

This thesis tackles the NO2 monitoring problem by employing carbon nanotube

field-effect transistors (CNT-FETs) as sensing elements, hence extending

the ubiquitous Internet-of-Things (IoT) applications, i.e., novel air quality

monitoring systems. The first prototype design proposes an embedded

system that can interface up to four CNT-FETs and may expand the IoT domain

for environmental and lifestyle applications. The platform performance

is demonstrated using a CNT-FET nanosensor, exposed to NO2 gas concentrations

from 200 ppb down to 1 ppb. The sensor signals are measured for

NO2 concentrations as low as 1 ppb, achieving a 3σ limit of detection (LOD)

of 23 ppb with an R2 linear fit coefficient of 0.95. Although this prototype offers

custom configuration, i.e., range, bandwidth, sampling rate, acquisition

time intervals, SD card, and Bluetooth Low Energy (BLE) connection, its

average power consumption of 64.5mW is relatively high.

Keywords:

Scientific Reports on Micro and Nanosystems

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