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

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.

Automated summary

Continuous monitoring of taste-inducing ions and molecules in liquids is crucial for the development of electronic tongues (E-tongues). This study focuses on the highly selective and sensitive real-time detection of Na+ due to its importance in determining the saltiness of food. The researchers designed a graphene-based channel decorated with Calix[4]arene and Nafion, which act as a receptor and a molecular sieve respectively, to enhance selectivity and sensitivity and prolong the device's lifespan. By combining the device with a microfluidic channel, dynamic on-off functions were achieved. The device exhibits highly selective and sensitive Na+ detection properties compared to other molecules/ionic species and has a lifespan of at least 220 days. It can also accurately distinguish real beverages containing Na+, as demonstrated by principal component analysis. These findings suggest that the device has the potential to become a platform for E-tongues in the future.