Development of a wireless vitamin B₂ sensor by using flexible and disposable screen-printed electrode modified with g-C₃N₄ based ternary composite

Water-soluble vitamin B₂ (riboflavin, RF) is essential for the metabolism and well-being of living things because it facilitates the synthesis of red blood cells, maintains the normal operation of the skin, eyes, and nerves, and helps turn food into energy. Consequently, creating a portable, wireless, and sensitive RF detection technique is crucial for clinical diagnosis as well as the food sector. In this work, we present a novel, flexible, and disposable homemade screen-printed electrode (HSPE) interfaced with a portable, wireless sensor system for selective and sensitive RF detection. The HSPE was fabricated using a cellulose-coated mulberry paper substrate, onto which a ternary composite of graphitic carbon nitride (g-C₃N₄) was deposited to enhance its electrochemical properties. The developed sensor exhibited prominent analytical performance, with high selectivity, reproducibility, low detection limit (LOD, 2.78 nM), high sensitivity (1724.76 μA μM⁻¹ cm⁻²), rapid response time (5 s), and a wide linear detection range (0.01–0.8 μM, R² = 0.97). The HSPE demonstrated effective real-time RF detection in diverse food samples, including rice, beans, chicken, potatoes, and yogurt, achieving good recovery rates. Integrated with a portable, wireless sensor device based on the Arduino Nano 33 Internet of Things (IoT), the system detected RF via open-circuit potential (OCP) changes and transmitted data wirelessly for remote monitoring through an Android mobile application. The device successfully distinguished RF presence with a performance comparable to larger-scale systems, demonstrating high potential for commercial deployment.