A low-cost portable spectrophotometer

In this work we present an electronic open hardware project for building a low-cost portable contact spectrophotometer. The project is based on a low-cost, pre-cabled on-board spectral sensor designed for device embedding. It is an off-the-shelf “low cost” component based on the AS7265x Smart Spectral Sensor chip family which consists of three sensor devices: AS72651 with master capability, AS72652, and AS72653. This integrated sensor is capable of measures on 18 spectral channels, ranging from 410nm to 940nm. Each AS7265x component has two integrated LED drivers with programmable current and can be timed for electronic shutter applications. Features include UART or I2C slave digital interface, 16-bit ADC with digital access, and programmable LED drivers. The device prototype we have built has also a GPS and a DHT (temperature and humidity) sensor to collect data to factor from the environment when measuring spectral information. Here we describe its main characteristics and present some preliminary tests and calibration.