A simple approach to develop a paper-based biosensor for real-time uric acid detection.

The current work reports the development of an inexpensive real-time sensing module for uric acid detection on a simple, disposable paper substrate. Detection is based on a capacitive measurement system using functional ZnO hexagonal rods on pulse-electrodeposited Cu interdigitated electrodes (IDEs) over hydrophobic A4 paper. Both the prepared hydrophobic A4 paper and ZnO hexagonal rods are well characterized using field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), UV-visible spectrophotometry (UV-Vis), Raman spectroscopy, and contact angle measurement. Arduino IDE software is used to configure the Arduino Mega board to evaluate the change in the capacitance value and to display the corresponding uric acid concentration on a liquid crystal display (LCD) screen. The experimental result shows the linear relationship in the range of 0.1 mM-1 mM concentration of uric acid with a high sensitivity of 9.00 μF mM ^-1 cm ^-2 at 0.1 mM. The results indicate that the developed capacitance measurement unit can be employed for the early screening of uric acid in real samples for clinical applications. The reported proof-of-concept has huge potential towards the development of a disposable and inexpensive biosensor platform.