Influence of Raised Ambient Temperature on a Sensor Node Using Step-Stress Test

The monitoring of environmental condition, together with soil parameter, is extremely important in precision farming technologies. One of the best solutions to implement environmental monitoring system in agriculture is to use a wireless mesh network to cover large area and ensure fault tolerance. A low-cost and low-power sensor node for mesh architectures has been developed and tested in this work. The node is based on a system on a chip microcontroller and few sensors to acquire air temperature, air humidity, soil temperature, soil moisture, and solar radiation. Generally, the effects of temperature on the dynamic metrological performance and on the reliability of wireless sensor network are not adequately dealt with. Moreover, no international standard for the environmental test of wireless sensor networks is available. In this article, a temperature step-stress test profile was implemented to characterize the behavior of the prototype at different temperature, from 20 °C up to 80 °C (step of 5 °C) using a climatic chamber. The aim of the test was to characterize which are the effects of the overheating on the current consumption, the sensor response, the analog-to-digital converter, and the digital-to-analog converter. The experimental test highlights some minor anomalies. However, all the unexpected behaviors are not caused by permanent failure mechanisms that lead to failure in the whole node. They are simple drifts that disappear when temperature returns to the standard environmental conditions.