Rationally designed graphene channels for real-time sodium ion detection for electronic tongue

Abstract

Monitoring taste-inducing ions and molecules continuously in liquids or solutions is of great considerable matter for the realization of the electronic tongue (E-tongue). Particularly from the five major tastes, the highly selective, sensitive detection of Na+ in real-time is prioritized. Prioritization is due to the saltiness of food is the key ingredient in most meals. Nevertheless, existing Na+ detecting devices have relatively low performances of selectivity, sensitivity, and lack of on–off functions. Additionally, conventional devices significantly deteriorate in capacity due to repetitive usage or lifetime shortage by degradation of the sensing material. Herein, a graphene-based channel was rationally designed by the facile decoration of Calix[4]arene and Nafion to address this issue. They act as a receptor and a molecular sieve, respectively, to enhance selectivity and sensitivity and elongate the life expectancy of the device. This device was merged with a microfluidic channel to control the injection and withdrawal of solutions to fulfill dynamic on–off functions. The fabricated device has highly selective, sensitive Na+ detection properties compared to other 10 molecule/ionic species. Dynamic on–off functions of the device were available, also possesses a long lifespan of at least 220 days. Additionally, it can precisely discriminate real beverages containing Na+, which can be observed by principal component analysis plot. These features offer the possibility of ascending to a platform for E-tongues in near future. (Figure presented.).