On-chip integrated silicon bulk-micromachined soil moisture sensor with electronics and bus interface

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

A influência de variáveis ambientais no crescimento de espécies/procedências de Eucalyptus spp. nos estados de Minas Gerais e Espírito Santo.

Foram analisados onze experimentos de introdução de espécies e procedências potenciais de Eucalyptus instalados em várias localidades dos estados de Minas Gerais e Espírito Santo. O estudo da influência de variáveis ambientais dos locais de introdução no crescimento em altura dessas espécies, aos três anos e meio de idade, permitiu concluir que a altitude do local do experimento foi a variável que mais influenciou o crescimento em altura de Eucalyptus camaldulensis, E. dunnii, E. grandis, E. pellita e E. tereticornis; o déficit hídrico isoladamente influenciou significativamente apenas o crescimento em altura de E. urophylla; a temperatura média e o total anual de precipitações não influenciaram isoladamente o crescimento em altura das oito espécies estudadas, e que é possível prever o comportamento das espécies e procedências em relação ao crescimento em altura, conhecendo-se a altitude, déficit hídrico e total anual médio de precipitações do local de introdução

On-chip integrated silicon bulk-micromachined soil moisture sensor based on the DPHP method

This paper reports the design, modelling, fabrication and assembly of a silicon bulk-micromachined soil moisture microsensor using the Dual-Probe Heat-Pulse (DPHP) method. Soil humidity measurement is essential to studysoil preservation and control the development of plants, namely in closed ecosystem. The DPHP method uses a heater (Peltier effect) and a temperature probe (Seebeck effect) to determine the volumetric heat capacity of the soil and hence water content ( θv). This is the first time that the DPHP method is implemented in a microdevice and the first integrated sensor for soil moisture. This microdevice is more suited to measure at different soil depths in a non-destructive and automated manner.Agricultural and Agro-industrial Science and Technology Institute of the University of Trás-os-Montes and Alto Douro

Caracterização de resíduos gerados em análises químicas de tecidos vegetais.

Este trabalho apresenta a caracterização dos resíduos gerados em análises químicas de tecidos vegetais do Laboratório de Análises de Solos e Plantas - LASP da Embrapa Amazônia Ocidental

Diagnóstico rápido participativo (DRP) como método de avaliação do programa de gerenciamento de resíduos laboratoriais (PGRL).

Na Embrapa, o DRP vem sendo utilizado pelo grupo de educação ambiental que adaptou o nome Diagnóstico Rural Participativo para Diagnóstico Rápido Participativo

A multi-chip-nodule micro-system for soil moisture measurements

This study presents a Multi-Chip-Module-based (MCM) micro-system suited for irrigation control and management applications. The micro-system includes the soil moisture sensor and an analogue-to-digital converter with signal processing circuitry. The same basic fabrication concepts and materials which made microelectronics successful are now being adapted to making low-cost, small, and high-performance sensor systems with integrated electronics on the same micro-system. Since this sensor has low-cost fabrication for mass production, a network could be implemented in order to achieve an accurate measurement of the soil moisture at the plant root level. A dual-probe heat-pulse technique is used (measurement of the maximum temperature rise at some distance from the heater, after applying a heat-pulse) to determine the volumetric heat capacity and, hence, the water content of the soil. The sensor module is about 30 mm long, 6 mm wide, and 0.8 mm in height; the probe pitch is 3 mm allowing small-scale spatial measurements of soil moisture, which can be made near the soil surface where large root densities are found. The heater uses a nickel-chrome resistor for resistive heating (thermo resistive effect – Joule heat). The temperature sensors (probe and reference) are highaccuracy CMOS smart temperature sensors

A CMOS mixed-signal interface with a RF transmitter for a micromachined soil moisture sensor

This paper describes a CMOS mixed-signal interface with a RF transmitter. This die is assembled in a Multi-Chip-Module (MCM) micro-system together with the micromachined soil moisture sensor to achieve a cost effective solution with accurate and reliable measurements for soil moisture in agriculture. The soil moisture probe, based on Dual-Probe Heat-Pulse (DPHP) method, is fabricated in bulkmicromachining technology. The DPHP method is based on the measurement of the maximum temperature rise at some distance from the heater, after applying a heat-pulse. The measurement of the temperature rise is obtained by subtracting soil temperature from the probe temperature. The mixed-signal interface is based on a pre-amplification stage and first-order sigma-delta modulator. The bit-stream output of the modulator is then applied to a counter as a first order decimation filter thus providing a 12-bit readout sample. Prior to transmission, data is encoded as a pulse width modulated (PWM) signal and then transmitted by means of an amplitude shift-keying (ASK) modulation. The transmitter features a VCO phase locked to the quartz crystal reference of 13.56 MHz to achieve a carrier frequency of 433.92 MHz. A RF power amplifier based on class E topology was chosen. The CMOS mixed-signal interface with a RF transmitter has been implemented in a single-chip using a standard CMOS process (AMI 0.7 µm, n-well, 2 metals and 1poly)

Modeling and simulation of a silicon soil moisture sensor based on the DPHP method for agriculture

A silicon soil moisture sensor, based in the dual-probe heat-pulse (DPHP) method, was modeled and simulated for achieving, with low cost, accurate and reliable measurements. This method is based on the application of a heat pulse during a fixed interval of time. The maximum rise in temperature (∆Tm) is monitored by the measurement probe, placed at a certain distance of the heater source. A lowcost high-performance and small temperature sensor (a dynamic VPTAT generator) is required to be placed into the probe which have 0.912 mm in diameter and 20 mm long. If one considers the range of water contents, ratio of water mass to dry soil mass, in a typical agricultural soil (0.05 to 0.35m3 m¡3), the average sensitivity of the dual probe is about 1:95ºC per unit change (m3m-3 in water content forq = 400 Jm-1