'Institute of Electrical and Electronics Engineers (IEEE)'
Abstract
This paper presents an on-chip silicon bulkmicromachined Soil Moisture Sensor (SMS) for irrigation control in greenhouses. The system-on-a-chip includes the SMS,
readout electronics, self-test, calibration facilities and a digital bus interface for external data transmission. Moreover, this
low-cost device can be applied in several locations (e. g. per each plant root), and networked together with the 1-wire bus.
The heat-pulse technique is used (for measuring the maximum temperature on a distant point) to determine the volumetric
heat capacity and hence the water content of a porous media, such as soil. In order to validate this method, experimental results were achieved with a macrosensor based on the heat-pulse and capacitance methods. The capacitance method relates the volumetric water content with the capacitance change (dielectric properties) of a probe, inserted in the soil. Several tests were performed for different type of soils and
water contents. These results are compared with the measurements achieved using the conventional thermogravimetric method