A Smartphone-Enabled Imaging Device for Chromotropic Acid-Based Measurement of Nitrate in Soil Samples. - Veerabhadrappa Lavanya; Anshuman Nayak; Partha Deb Roy; Shubhadip Dasgupta; Subhadip Dey; Bin Li 008; David C. Weindorf; Somsubhra Chakraborty (Sensors, 2023)