A 3D-Printable smartphone accessory for plant leaf chlorophyll measurement

Plant health and nutrition are universally inferred from leaf chlorophyll content. This research developed a 3D-printed accessory which attaches to the ambient light sensor in a smartphone to estimate leaf chlorophyll content in five tropical plant species. It unveils 3D printing files and assembling details to freely built the accessory anywhere. It is made from a 3D-printed body, a lighting circuit and common spare parts to measure a 663 nm LED band transmission through intact plant leaves. This chlorophyll absorbing light band allows to measure its concentration. The device was tested by comparing its readings to the universal spectrophotometric test or by leaf parallel measurements with a standard SPAD 502™ meter, and it performed as well as these universal standard methods. Due to well-studied relationships between chlorophyll concentration and nutritional status of plants, and the ubiquitous presence of other sensors in smartphones today, the independent improvement and adoption of this smartphone-connected system would ease the spread of precision farming and digital agronomy practices throughout the different scales of agriculture.