Luminescent Smart Labels for the New Generation of Optical Sensing and Internet of Things

Sensors play a key role on the Internet of Things (IoT) providing monitoring inside and outside the communication networks in a multitude of parameters [1]. Challenges towards IoT lie in the lack of affordable strategies able to convert sustainably, a signal from an optical sensors network into a digital data sequence. The coupling of optical sensors to smartphones appears as an exciting strategy for the new generation of mobile optical (mOptical) sensing. Enlarged by the COVID-19 pandemic scenario healthcare services standout and the concepts of <i>eHealth</i> and <i>mHealth</i> (mobile-assisted eHealth) arose [2] being more and more explored towards the development of effective low-cost and sustainable systems that promote healthcare provision. Using the concept of colored multiplexed QR codes based on luminescent organic-inorganic inks modified by lanthanides, customized smart labels formed by two independent layers and/or smart location provide simultaneous tracking and multiple synchronous temperature reading with maximum sensitivity values among the best values in the literature in the physiological temperature range overwhelming the state of the art of optical sensor for healthcare services provided electronically via the internet (eHealth) and mobile sensors (mHealth) [2]. In addition, the concept of super-modules built from adjacent spatial multiplexed modules was used to design a single QR code with, at least, the triple storage capacity of an analogous size black/white QR code, acting as a smart-tag ensuring restrict access and trackability [3].<br/>[1] Din et al. IEEE Access. 7 (2019) 7606.<br/>[2] Ramalho et al. Adv. Photonics Res. 2 (2021) 2000211; Adv. Photonics Res. (2021) 2100206. Adv. Sci. 6 (2019) 1900950.<br/>[3] Ramalho et al. Npj Flex. Electron. 4 (2020).