Portable, low-cost, Raspberry Pi-based optical sensor (PiSENS): continuous monitoring of atmospheric nitrogen dioxide

Saiz, Ernesto; Banicevic, Ivana; Espinoza Torres, Sergio; Bertata, Salma; Picasso, Gino; O'Brien, Matthew; Radu, Aleksandar

Abstract

We have developed a sensing system that utilizes a low-cost computer (Raspberry Pi) and its imaging camera as an optical sensing core for the continuous detection of NO2 in the air (PiSENS-A). The sensor is based on colour development as a consequence of the interaction of the gas with an absorbing solution. The PiSENS-A is thoroughly calibrated over the hourly mean which is used as one of the key metrics in evaluating air quality. The calibration was performed in the range of 0 < [NO2] < 476 μg m−3 chosen to contain the threshold used to determine compliance to the UK's Air Quality Standard Regulations (2010) expressed as a maximum of 18 permitted exceedances of [NO2]hourly mean = 200 μg per m3 per year. Lab-based measurements were evaluated against UV-vis. The average precision expressed as a relative standard deviation was: RSD% = 2.8%, while the correlation of mock samples was excellent (Pearson's r = 1.000). Field-based measurements were evaluated against chemiluminescence-based instrument exhibiting a correlation coefficient of R2 = 0.993. The PiSENS-A was also deployed as an independent air quality analyser at the Keele University campus.

• Journal Article Type: Article
• Acceptance Date: Dec 22, 2022
• Online Publication Date: Dec 22, 2022
• Deposit Date: May 30, 2023
• Journal: Analytical Methods
• Print ISSN: 1759-9660
• Electronic ISSN: 1759-9679
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 15
• Issue: 4
• Pages: 482-491
• DOI: https://doi.org/10.1039/d2ay01433e
• Keywords: General Engineering; General Chemical Engineering; Analytical Chemistry