Autonomous soil moisture sensor based on nanostructured thermosensitive resistors powered by an integrated thermoelectric generator

Abstract An autonomous single heat pulse probe porous ceramic soil moisture sensor powered by a thermoelectric generator (TEG) is presented. The sensor uses nanostructured thermosensitive resistors fabricated on the same ceramic substrate of the TEG. The nanostructured resistors, fabricated by printing PbS quantum dots, present a very high thermal coefficient (−16 × 10 3  ppm/°C) and, used in a bridge configuration with conventional precision and low thermal coefficient SMD metal film resistors, result in a high sensitivity temperature sensor. A laboratory prototype of the sensor showed a voltage variation of 2.4 mV in the output of the bridge when the volumetric water content of the soil changed from 5% to 40%. To complete the autonomous system, we designed an ultra low-power electronic interrogator which, when powered only by the 3 F supercapacitor of the integrated TEG energy harvesting system, was able to take daily measurements up to 5 days without harvesting energy.

[1]  G. S. Campbell,et al.  Calibration and Temperature Correction of Heat Dissipation Matric Potential Sensors , 2002 .

[2]  G. Kluitenberg,et al.  Comparison of Single and Dual Probes for Measuring Soil Thermal Properties with Transient Heating , 1994 .

[3]  M. Kanatzidis,et al.  Electron doping in bottom-up engineered thermoelectric nanomaterials through HCl-mediated ligand displacement. , 2015, Journal of the American Chemical Society.

[4]  Luzius Matile,et al.  Characterization of a New Heat Dissipation Matric Potential Sensor , 2013, Sensors.

[5]  Gaylon S. Campbell,et al.  Soil thermal conductivity , 1990 .

[6]  Suat Irmak,et al.  Autonomous precision agriculture through integration of wireless underground sensor networks with center pivot irrigation systems , 2013, Ad Hoc Networks.

[7]  Elnatan Chagas Ferreira,et al.  Proposal of a novel heat dissipation soil moisture sensor , 2011 .

[8]  Elnatan Chagas Ferreira,et al.  A high sensitivity single-probe heat pulse soil moisture sensor based on a single npn junction transistor , 2013 .

[9]  Raul Morais,et al.  Multi-functional probe for small-scale simultaneous measurements of soil thermal properties, water content, and electrical conductivity , 2006 .

[10]  Jan W. Hopmans,et al.  Design and Numerical Analysis of a Button Heat Pulse Probe for Soil Water Content Measurement , 2009 .

[11]  Olivier Marloie,et al.  Correcting the Temperature Influence on Soil Capacitance Sensors Using Diurnal Temperature and Water Content Cycles , 2012, Sensors.

[12]  J H Norikane,et al.  A comparison of soil moisture sensors for space flight applications. , 2005, Applied engineering in agriculture.

[13]  Elnatan Chagas Ferreira,et al.  Autonomous Multisensor System Powered by a Solar Thermoelectric Energy Harvester With Ultralow-Power Management Circuit , 2015, IEEE Transactions on Instrumentation and Measurement.

[14]  Christofer Hierold,et al.  Optimization and fabrication of thick flexible polymer based micro thermoelectric generator , 2006 .

[15]  José Higino Correia,et al.  Modeling, simulation and testing of a silicon soil moisture sensor based on the dual-probe heat-pulse method , 2004 .

[16]  Qi Zhang,et al.  Solar micro-energy harvesting based on thermoelectric and latent heat effects. Part II: Experimental analysis , 2010 .

[17]  G. Campbell,et al.  Probe for Measuring Soil Specific Heat Using A Heat-Pulse Method , 1991 .