Rapid on-site detection of riboflavin using nanozyme GdSn-MnO₂ based printed electrode interface with portable and wireless sensor device

Maintaining optimal levels of vitamin B₂ (riboflavin) in the diet is crucial for maintaining overall health. However, the development of portable, cost-effective, and wireless electrochemical sensing systems for onsite riboflavin detection remains a significant challenge. In this study, a portable and wireless electrochemical sensing platform was developed, integrating a flexible printed electrode modified with gadolinium (Gd) and tin (Sn) co-doped manganese dioxide (MnO₂) nanoplates. The electrode was fabricated on a polyethylene terephthalate (PET) substrate using screen-printing technology with activated carbon paste and Ag/AgCl ink. This non-enzymatic sensing approach was optimized by modifying the electrode surface with GdSn-MnO₂ nanoplates at varying Gd:Sn ratios (1:1, 1:2, and 2:1), enhancing both sensitivity and selectivity. Experimental validation and Recurrent Neural Network (RNN) analysis confirmed that an equimolar Gd:Sn ratio (1:1) provided optimal sensor performance. The developed sensor exhibited ultra-high sensitivity (3.97 μA mM⁻¹cm⁻¹), with a detection limit of 3 nM, excellent selectivity, and superior recovery in real-world applications. Furthermore, the flexible electrode was integrated with a portable wireless sensing device employing an Arduino Nano 33 IoT module, enabling riboflavin detection via open-circuit potential (OCP) measurements. Real-time data transmission was achieved wirelessly through an Android-based mobile application. The device exhibits excellent selective sensing, evident from a decrease in electrode potential from 0.19 V to 0.01 V due to strong hydrogen bonding and electrostatic interaction among electrode surface and analyte (RF). The proposed sensor demonstrated performance comparable to conventional large-scale laboratory systems, underscoring its potential for practical onsite food analysis.