QRsens: Dual-purpose quick response code with built-in colorimetric sensors
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AuthorEscobedo Araque, Pablo; Ramos Lorente, Celia Esperanza; Ejaz, Ammara; Erenas Rodríguez, Miguel María; Martínez Olmos, Antonio; Carvajal Rodríguez, Miguel Ángel; García-Núñez, Carlos; Orbe Payá, Ignacio De; Capitán Vallvey, Luis Fermín; Palma López, Alberto José
QR codesColorimetric sensorsColour correctionSmartphoneQR analytical devices
P. Escobedo et al. QRsens: Dual-purpose quick response code with built-in colorimetric sensors. Sensors & Actuators: B. Chemical 376 (2023) 133001 [https://doi.org/10.1016/j.snb.2022.133001]
SponsorshipSpanish MCIN/AEI/10.13039/ 501100011033/ (Projects PID2019–103938RB-I00, ECQ2018–004937- P and grant IJC2020–043307-I); Junta de Andalucía (Projects B- FQM-243-UGR18, P18-RT-2961); European Regional Development Funds (ERDF); European Union NextGenerationEU/PRTR
QRsens represents a family of Quick Response (QR) sensing codes for in-situ air analysis with a customized smartphone application to simultaneously read the QR code and the colorimetric sensors. Five colorimetric sensors (temperature, relative humidity (RH), and three gas sensors (CO2, NH3 and H2S)) were designed with the aim of proposing two end-use applications for ambient analysis, i.e., enclosed spaces monitoring, and smart packaging. Both QR code and colorimetric sensing inks were deposited by standard screen printing on white paper. To ensure minimal ambient light dependence of QRsens during the real-time analysis, the smartphone application was programmed for an effective colour correction procedure based on black and white references for three standard illumination temperatures (3000, 4000 and 5000 K). Depending on the type of sensor being analysed, this integration achieved a reduction of ~71 – 87% of QRsens’s dependence on the light temperature. After the illumination colour correction, colorimetric gas sensors exhibited a detection range of 0.7–4.1%, 0.7–7.5 ppm, and 0.13–0.7 ppm for CO2, NH3 and H2S, respectively. In summary, the study presents an affordable built-in multi-sensing platform in the form of QRsens for in-situ monitoring with potential in different types of ambient air analysis applications.