Detection technique for vitamin D 3 using Er-doped TiO 2 nanowire-based UV photodetector

Vitamin D3 acts as a crucial biomarker for various diseases. Current methods for vitamin D3 detection are time-consuming, expensive, and require trained personnel. We report a simple and cheap photodetector (PD)-based vitamin D3 detection technique for the first time using Ag nanoparticles-covered Er-doped TiO2 nanowires. The operational stability of the device was tested under the dark as well as the UV light illumination. Vitamin D3 solution produced absorption bands at 222 and 280 nm, respectively. The PD current density varied from 1.29  ×  10  −  4  A  /  cm2 to 1.74  ×  10  −  4 at −4  V for pure ethanol solution and 20  pg  /  ml D3 solution, respectively (under 220 nm illumination). The average absolute current values were reduced from 3.25 nA (220 nm) and 2.9 nA (340 nm) for 5  pg  /  ml to 2.95 nA (220 nm) and 2.54 nA (340 nm) for 30  pg  /  ml D3 solution, respectively. The current gradually increased up to 3.34 nA (220 nm) and 2.7 nA (340 nm) as the concentration was increased up to 80  pg  /  ml. The PD current/vitamin D3 concentration decreases exponentially from 0.58 to 0.03  nA  /  g  /  ml) for 5 and 80  pg  /  ml, respectively, under 220 nm excitation, from which an unknown concentration of vitamin D3 can be obtained.