An Ultra-Broadband Near-Infrared Cr³⁺-Activated Gallogermanate Mg₃Ga₂GeO₈ Phosphor as Light Sources for Food Analysis

Abstract

A detailed nondestructive analytical method for quantitative food analysis was established by using a self-fabricated NIR-LED light source combined with Mg3Ga2GeO8 (MGGO) phosphor and a blue LED chip in one package, which can be integrated into smartphones. The phosphor of MGGO:Cr3+ exhibits ultra-broadband NIR emission in the range of 650–1200 nm, which matches well with the overtones of molecular vibrations (e.g., O–H, C–H, and N–H) presented in food composition. The detailed crystal structure of MGGO was investigated by powder XRD Rietveld refinements, HRTEM images, and the corresponding SAED. Luminescence properties based on different Cr3+ ions positions were investigated according to Gaussian peak fitting. Owing to the NIR response to organic elements, the working curves between absorbance and water content as well as sugar degree of pears and bananas were plotted. Then the reliability and veracity of the nondestructive analytical method were evaluated (R2 = 0.9988). All the results suggest that the ultra-broadband NIR emission of MGGO:Cr3+ phosphor has potential application as light sources integrated into smartphones for nondestructive food analysis.