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|A silicon probe with integrated microelectronics for soil moisture measurements
Cunha, J. Boaventura
Correia, J. H.
|Instrumentation and control
|WORLD CONGRESS OF COMPUTERS IN AGRICULTURE AND NATURAL RESOURCES, Iguaçu Falls, Brazil, 2001 – “World Congress of Computers in Agriculture and Natural Resources : proceedings”. [S.l. : s.n., 2001]. p. 440-447.
|This work presents an on-chip silicon bulk-micromachined Soil Moisture Sensor (SMS) suited for irrigation control and management applications. The same basic fabrication concepts and materials, which made microelectronics successful, are now being adapted to making low-cost, small, high-performance sensor systems with integrated electronics on the same chip. As a result, this system-on-a-chip includes the SMS, readout electronics, self-test, calibration facilities and a digital bus interface for external data transmission. Moreover, since this sensor has low-cost, it could be employed several sensors networked together with the 1-wire bus, to achieve an accurate measure of the soil moisture at the plant root level. A 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. This method is based on the Joule effect (heater probe shank) and in Seebeck effect (thermopile – temperature probe shank). The heater and the thermopile are suspended on a dielectric window to reduce undesired heat conduction to the substrate (silicon is a good heat conductor). Thermal simulations of the bulk-micromachined SMS are performed to test sensor performance. In order to validate the method, simulations are made and experimental results were achieved with a macrosensor based on this technique. The results were compared with the measurements performed by the conventional thermo-gravimetric method.
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|DEI - Artigos em atas de congressos internacionais
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