The invention comprises a diaper sensor device comprising at least two sensor units each comprising at least a temperature sensor and a humidity sensor； optionally a positional sensor； a microcontroller communicating with the sensors and comprising a transmitter for transmitting data from the sensors； a power unit supplying power to the sensors, the microcontroller and the transmitter； a flexible watertight casing； housing the sensors, the transmitter； and the power unit, and fastening means for fastening the diaper sensor device on the outside of the diaper.Furthermore the invention comprises a method and a system for determining the existence and class of human excreta in a diaper.
