Development and Application of the Single-Spiral Inductive-Capacitive Resonant Circuit Sensor for Wireless, Real-Time Characterization of Moisture in Sand

A wireless, passive embedded sensor was designed and fabricated for monitoring moisture in sand. The sensor, consisted of an inductive-capacitive (LC) resonant circuit, was made of a printed spiral inductor embedded inside sand. When exposed to an electromagnetic field, the sensor resonated at a specific frequency dependent on the inductance of the inductor and its parasitic capacitance. Since the permittivity of water was much higher than dry sand, moisture in sample increased the parasitic capacitance, thus decreasing the sensor’s resonant frequency. Therefore, the internal moisture level of the sample could be easily measured through tracking the resonant frequency using a detection coil. The fabrication process of this sensor is much simpler compared to LC sensors that contain both capacitive and inductive elements, giving it an economical advantage. A study was conducted to investigate the drying rate of sand samples of different grain sizes. The experimental data showed a strong correlation with the actual moisture content in the samples. The described sensor technology can be applied for long term monitoring of localized water content inside soils and sands to understand the environmental health in these media, or monitoring moisture levels within concrete supports and road pavement.

[1]  M J Dill,et al.  The long-term monitoring of civil engineering and building structures—developments in techniques for monitoring corrosion in reinforced and post-tensioned concrete , 1998 .

[2]  Claude Pellet,et al.  Dynamic behavior of a chemical sensor for humidity level measurement in human breath , 2004, IEEE Transactions on Instrumentation and Measurement.

[3]  C. Balanis.  Advanced Engineering Electromagnetics , 1989 .

[4]  Denis Flandre,et al.  High-sensitivity capacitive humidity sensor using 3-layer patterned polyimide sensing film , 2003, Proceedings of IEEE Sensors 2003 (IEEE Cat. No.03CH37498).

[5]  Maohua Wang,et al.  Wireless sensors in agriculture and food industry — Recent development and future perspective , 2005 .

[6]  J. Stafford.  Remote, non-contact and in-situ measurement of soil moisture content: a review , 1988 .

[7]  J. Mills-Beale,et al.  A Wireless, Passive Embedded Sensor for Real-Time Monitoring of Water Content in Civil Engineering Materials , 2008, IEEE Sensors Journal.

[8]  Craig A. Grimes,et al.  Design and application of a wireless, passive, resonant-circuit environmental monitoring sensor , 2001 .

[9]  Ermanno G. Grinzato,et al.  Quantitative infrared thermography in buildings , 1998 .

[10]  K G Ong,et al.  Monitoring of bacteria growth using a wireless, remote query resonant-circuit sensor: application to environmental sensing. , 2001, Biosensors & bioelectronics.

[11]  Shigeru Nakayama.  Development of a microwave moisture sensor for aggregates , 1995 .

[12]  K. G. Ong,et al.  A resonant printed-circuit sensor for remote query monitoring of environmental parameters , 2000 .

[13]  Ning Wang,et al.  Review: Wireless sensors in agriculture and food industry-Recent development and future perspective , 2006 .

[14]  Craig A. Grimes,et al.  Wireless passive resonant-circuit sensors for monitoring food quality , 2002, Optics East.

[15]  P. Bowen,et al.  Changes in portlandite morphology with solvent composition: Atomistic simulations and experiment , 2011 .

[16]  Craig A. Grimes,et al.  A Carbon Nanotube-based Sensor for CO2 Monitoring , 2001 .

[17]  陈谦,et al.  Capacitive soil moisture sensor , 2014 .

[18]  K. Watanabe,et al.  A digital hygrometer , 1988 .

[19]  Walter Lang,et al.  Applying autonomous sensor systems in logistics—Combining sensor networks, RFIDs and software agents , 2006 .

[20]  Zhuoqiu Li,et al.  A study on thermal self-diagnostic and self-adaptive smart concrete structures , 2000 .

[21]  Robert Meline,et al.  Smart Pebble: wireless sensors for structural health monitoring of bridge decks , 2003, SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[22]  K. G. Ong,et al.  A CARBON NANOTUBE-BASED SENSOR FOR CO 2 MONITORING , 2001 .

[23]  Craig A. Grimes,et al.  Remote Query Resonant-Circuit Sensors for Monitoring of Bacteria Growth: Application to Food Quality Control , 2002 .