A PCB Technology Moisture Content and Electrical Conductivity Sensor Probe for Agricultural and Horticultural Applications

2014 ◽  
Vol 2014 (DPC) ◽  
pp. 000984-001011
Author(s):  
Robert N. Dean ◽  
Elizabeth Guertal ◽  
Adam Newby ◽  
Glenn Fain
Keyword(s):  
Electrical Conductivity ◽  
Plant Growth ◽  
Moisture Content ◽  
Test Data ◽  
Printed Circuit Board ◽  
Low Cost ◽  
Circuit Board ◽  
Conductivity Sensor ◽  
Irrigation Volume ◽  
Sensor Probe

Commercial printed circuit board (PCB) technology affords the realization of low-cost sensor probes for agricultural and horticultural applications. Plant growth can be optimized when the soil (in field crop applications) or the substrate (in greenhouse crop applications) properties can be measured and properly adjusted. Two important parameters are moisture content and electrical conductivity. Measuring moisture content allows the grower to better time irrigation for most efficient crop growth. Accurate moisture content measurement also allows the grower to apply sufficient irrigation volume for optimum plant growth while avoiding excessive irrigation volume. Likewise, measuring the electrical conductivity reveals useful information regarding ions in the soil or substrate, which can be used to optimize the application of plant nutrients or manage soil salinity. Commercial soil probes are expensive, which limits their widespread use in commercial applications. PCB probes, on the other hand, can be very inexpensive and can quickly be redesigned to modify the form factor for different applications. These sensors make use of the materials and processes inherent in commercial PCB manufacturing, including the FR4 substrate, patterned Cu cladding and soldermask. The non-conductive E-glass FR4 substrate is used as the rigid backbone of the sensor probe. The patterned Cu cladding is used for electrodes and signal traces. The polymeric soldermask is used as a thin insulating and moisture barrier layer. With these materials, insulated fringing field sensors can be realized on the surface of the PCB to measure moisture content, while exposed metal pads on the surface can be used to measure electrical conductivity. Additionally, the PCB probe is directly compatible with the integration of any desired integrated electronic components. Furthermore, the turnaround time for a new PCB sensor design can be as little as 24 hours at modest cost, making this technology economically superior to traditional sensor technologies, such as silicon based MEMS, where it can take months to realize a new design and be very expensive. A prototype sensor probe has been designed, fabricated and evaluated. Test data is analyzed, compared with test data from traditional sensor probes and presented.

A PCB Technology Electrical Conductivity Sensor for the Measurement of Saltwater Contamination

2015 ◽  
Vol 2015 (DPC) ◽  
pp. 001048-001069 ◽  
Author(s):  
Robert N. Dean ◽  
Frank Werner ◽  
Mark Adams
Keyword(s):  
Electrical Conductivity ◽  
Saltwater Intrusion ◽  
Coastal Areas ◽  
Gas Production ◽  
Freshwater Ecosystems ◽  
Circuit Board ◽  
Conductivity Sensor ◽  
Natural Factors ◽  
Freshwater Aquifers ◽  
Sensor Probe

Saltwater intrusion is when sea water moves into freshwater aquifers and contaminates them. It can be a serious problem for coastal communities and inland ecosystems. A number of factors, both natural and manmade, contribute to this contamination. Natural factors include events such as storm surges from hurricanes that push seawater into inland freshwater bodies. However, manmade factors contribute far more to saltwater intrusion than natural factors. The biggest human factor is the overuse of freshwater aquifers in coastal areas. Saltwater has a higher density than freshwater, and hence a higher static pressure. So when a freshwater aquifer is partially drained by over usage, the higher pressure saltwater will percolate through the bedrock into the aquifer under the freshwater. Contamination of the freshwater body then occurs through dispersion and diffusion. Manmade canals and channels for shipping, drainage and irrigation can also provide a pathway for seawater to move into coastal bodies of freshwater. Oil and gas production and mining can also contribute to saltwater contamination of freshwater. Saltwater contamination can render freshwater aquifers non-potable, kill freshwater fish and other inhabitants, kill freshwater plants and deleteriously affect inland freshwater ecosystems in coastal areas. Dissolved salt ions in water are excellent charge carries, resulting in a large difference in the electrical conductivity between freshwater and saltwater. Therefore the measurement of the electrical conductivity of a water sample can be used to gauge the level of possible saltwater contamination. Commercial printed circuit board (PCB) technology affords the realization of a low-cost sensor probe for measuring the electrical conductivity of aqueous samples. This sensor makes use of the materials and processes inherent in commercial PCB manufacturing, including the FR4 substrate, patterned Cu cladding and soldermask. The non-conductive E-glass FR4 substrate is used as the rigid backbone of the sensor probe. The patterned Cu cladding is used for electrodes and signal traces. The polymeric soldermask is used as a thin insulating and moisture barrier layer. With these materials, the sensor consists of two planar exposed metal pads on the surface that are used to measure electrical conductivity. Additionally, the PCB probe is directly compatible with the integration of any desired integrated electronic components and/or other sensors. Furthermore, the turnaround time for a new PCB sensor design can be as little as 24 hours at modest cost, making this technology economically superior to traditional sensor technologies, such as silicon based MEMS, where it can take months to realize a new design and be very expensive. A prototype PCB electrical conductivity sensor probe has been designed, fabricated and evaluated with mixtures of freshwater and seawater, demonstrating its usefulness.

A PCB Environmental Sensor for Use in Monitoring Drought Conditions in Estuaries

2016 ◽  
Vol 13 (4) ◽  
pp. 182-187 ◽  
Author(s):  
Robert N. Dean ◽  
Frank T. Werner
Keyword(s):  
Electrical Conductivity ◽  
Parallel Plate ◽  
Printed Circuit Board ◽  
Salinity Gradient ◽  
Low Cost ◽  
Life Forms ◽  
Circuit Board ◽  
Linear Characteristic ◽  
Drought Conditions ◽  
Salinity Levels

Estuaries occur in coastal regions worldwide and are important habitats for humans and other life forms. These fragile ecosystems are susceptible to the effects of prolonged drought conditions, resulting in changes in the salinity gradient across the estuary, which can adversely affect life forms living in and around the estuary. Electrical conductivity sensors are used to determine salinity of aqueous solutions, including water samples from estuaries. Conventional electrical conductivity sensors, consisting of orthogonally mounted thin parallel plate electrodes, are fragile and difficult to clean. Low-cost commercial printed circuit board technology is presented here as a vehicle to realize a robust planar sensor for determining salinity. This sensor's planar electrode configuration is inherently simpler and less fragile than a sensor with two orthogonally mounted thin parallel plate electrodes. Prototype planar sensors were designed, fabricated, and successfully tested in a freshwater-seawater solution ranging from 100% freshwater to 100% seawater, emulating the salinity levels encountered across many estuaries. The sensor test data demonstrated a linear characteristic with both conductance (R2 = 0.9995) and salinity (R2 = 0.9969) as a function of seawater concentration.

A Novel Wideband transition from Substrate Integrated Waveguide to Rectangular Waveguide

2020 ◽  
Vol 10 ◽  
Author(s):  
Keyur Mahant ◽  
Hiren Mewada ◽  
Amit Patel ◽  
Alpesh Vala ◽  
Jitendra Chaudhari
Keyword(s):  
Rectangular Waveguide ◽  
Printed Circuit Board ◽  
Low Cost ◽  
Single Layer ◽  
Circuit Board ◽  
Substrate Integrated Waveguide ◽  
Ka Band ◽  
Better Than ◽  
Millimeter Wave Circuits ◽  
Wideband Transition

Aim: In this article, wideband substrate integrated waveguide (SIW) and rectangular waveguide (RWG) transition operating in Ka-band is proposed Objective: In this article, wideband substrate integrated waveguide (SIW) and rectangular waveguide (RWG) transition operating in Ka-band is proposed. Method: Coupling patch etched on the SIW cavity to couple the electromagnetic energy from SIW to RWG. Moreover, metasurface is introduced into the radiating patch to enhance bandwidth. To verify the functionality of the proposed structure back to back transition is designed and fabricated on a single layer substrate using standard printed circuit board (PCB) fabrication technology. Results: Measured results matches with the simulation results, measured insertion loss is less than 1.2 dB and return loss is better than 3 dB for the frequency range of 28.8 to 36.3 GHz. By fabricating transition with 35 SRRs bandwidth of the proposed transition can be improved. Conclusion: The proposed transition has advantages like compact in size, easy to fabricate, low cost and wide bandwidth. Proposed structure is a good candidate for millimeter wave circuits and systems.

scholarly journals Highly Compact Through-Wire Microstrip to Empty Substrate Integrated Coaxial Line Transition

2021 ◽  
Vol 11 (15) ◽  
pp. 6885
Author(s):  
Marcos D. Fernandez ◽  
José A. Ballesteros ◽  
Angel Belenguer
Keyword(s):  
Printed Circuit Board ◽  
Low Cost ◽  
Coaxial Line ◽  
Circuit Board ◽  
Central Layer ◽  
Printed Circuit ◽  
Integrated Technology ◽  
Low Profile ◽  
The Many ◽  
High Degree

Empty substrate integrated coaxial line (ESICL) technology preserves the many advantages of the substrate integrated technology waveguides, such as low cost, low profile, or integration in a printed circuit board (PCB); in addition, ESICL is non-dispersive and has low radiation. To date, only two transitions have been proposed in the literature that connect the ESICL to classical planar lines such as grounded coplanar and microstrip. In both transitions, the feeding planar lines and the ESICL are built in the same substrate layer and they are based on transformed structures in the planar line, which must be in the central layer of the ESICL. These transitions also combine a lot of metallized and non-metallized parts, which increases the complexity of the manufacturing process. In this work, a new through-wire microstrip-to-ESICL transition is proposed. The feeding lines and the ESICL are implemented in different layers, so that the height of the ESICL can be independently chosen. In addition, it is a highly compact transition that does not require a transformer and can be freely rotated in its plane. This simplicity provides a high degree of versatility in the design phase, where there are only four variables that control the performance of the transition.

scholarly journals A Low-Cost Water Depth and Electrical Conductivity Sensor for Detecting Inputs into Urban Stormwater Networks

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3056
Author(s):  
Baiqian Shi ◽  
Stephen Catsamas ◽  
Peter Kolotelo ◽  
Miao Wang ◽  
Anna Lintern ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Water Depth ◽  
Asset Management ◽  
Low Cost ◽  
Rate Of Change ◽  
Urban Drainage ◽  
Urban Stormwater ◽  
High Resolution Data ◽  
Conductivity Sensor ◽  
Level Sensor

High-resolution data collection of the urban stormwater network is crucial for future asset management and illicit discharge detection, but often too expensive as sensors and ongoing frequent maintenance works are not affordable. We developed an integrated water depth, electrical conductivity (EC), and temperature sensor that is inexpensive (USD 25), low power, and easily implemented in urban drainage networks. Our low-cost sensor reliably measures the rate-of-change of water level without any re-calibration by comparing with industry-standard instruments such as HACH and HORIBA’s probes. To overcome the observed drift of level sensors, we developed an automated re-calibration approach, which significantly improved its accuracy. For applications like monitoring stormwater drains, such an approach will make higher-resolution sensing feasible from the budget control considerations, since the regular sensor re-calibration will no longer be required. For other applications like monitoring wetlands or wastewater networks, a manual re-calibration every two weeks is required to limit the sensor’s inaccuracies to ±10 mm. Apart from only being used as a calibrator for the level sensor, the conductivity sensor in this study adequately monitored EC between 0 and 10 mS/cm with a 17% relative uncertainty, which is sufficient for stormwater monitoring, especially for real-time detection of poor stormwater quality inputs. Overall, our proposed sensor can be rapidly and densely deployed in the urban drainage network for revolutionised high-density monitoring that cannot be achieved before with high-end loggers and sensors.

EFFECT OF HYDROTHERMAL TIME ON THE GROWTH OF ZnO NANORODS

2020 ◽  
pp. 84-91
Author(s):  
Hanh
Keyword(s):  
Printed Circuit Board ◽  
Low Cost ◽  
Cell Structure ◽  
Zno Nanorods ◽  
Zinc Nitrate ◽  
Circuit Board ◽  
Nitrate Hexahydrate ◽  
Hydrothermal Time ◽  
One Step ◽  
Surface Morphologies

In this work, ZnO nanorods (NRs) were successfully grown on printed circuit board substrates (PCBs) by utilizing a one-step, seedless, low-cost hydrothermal method. It was shown that by implementing a galvanic cell structure in an aqueous solution of 80 mM of zinc nitrate hexahydrate and hexamethylenetetramine, ZnO NRs can directly grow on the PCBs substrate without the assistance of a seed layer. The effect of hydrothermal time on the surface morphologies, and the crystallinity of the as-grown ZnO nanorods (NRs) was also investigated. The as-grown ZnO NRs also exhibited a significant enhancement in vertical growth and their crystallinity with 5 hour growth.

Nonlinear-Time-Dependent Analysis of Micro Via-In-Pad Substrates for Solder Bumped Flip Chip Applications

2002 ◽  
Vol 124 (3) ◽  
pp. 205-211 ◽  
Author(s):  
John H. Lau ◽  
S. W. Ricky Lee ◽  
Stephen H. Pan ◽  
Chris Chang
Keyword(s):  
Cross Sections ◽  
Flip Chip ◽  
Printed Circuit Board ◽  
Low Cost ◽  
Circuit Board ◽  
Test Results ◽  
Pcb Assembly ◽  
Creep Analysis ◽  
Chip Scale Package ◽  
Time Dependent Analysis

An elasto-plastic-creep analysis of a low-cost micro via-in-pad (VIP) substrate for supporting a solder bumped flip chip in a chip scale package (CSP) format which is soldered onto a printed circuit board (PCB) is presented in this study. Emphasis is placed on the design, materials, and reliability of the micro VIP substrate and of the micro VIP CSP solder joints on PCB. The solder is assumed to obey Norton’s creep law. Cross-sections of samples are examined for a better understanding of the solder bump, CSP substrate redistribution, micro VIP, and solder joint. Also, the thermal cycling test results of the micro VIP CSP PCB assembly is presented.

A PCB Sensor for Magnetic Materials

2019 ◽  
Vol 2019 (DPC) ◽  
pp. 001323-001342
Author(s):  
Robert N. Dean ◽  
Lauren E. Beckingham
Keyword(s):  
Magnetic Materials ◽  
Printed Circuit Board ◽  
Low Cost ◽  
Complex Impedance ◽  
Corrosion Products ◽  
Physical Contact ◽  
Circuit Board ◽  
Sensor Technology ◽  
Printed Circuit ◽  
Surrounding Environment

Printed circuit board (PCB) sensors are a sensor technology where the layout of traces on a PCB has been optimized so that the traces electromagnetically interact with the surrounding environment. These types of sensors can be manufactured at very low cost using standard commercially available low-cost printed circuit board fabrication. Exposed conductive electrodes on the circuit board are useful for measuring the electrical conductivity of the surrounding environment, and these sensors have been used in applications such as salinity measurement and dissolved ion content measurement of aqueous solutions. Insulated interdigitated electrode sensors are useful for capacitively analyzing the surrounding environment, and these sensors have been used to detect the presence of liquid water and to measure the moisture content of substances in physical contact with the sensor. Additionally, by measuring the complex impedance of the capacitive sensor over a wide frequency range, information concerning the chemical composition of the substance in contact with the sensor can be determined. In addition to conducive and capacitive PCB sensors, the third type of PCB sensor would be an inductive sensor. Although it is challenging to realize 3D coils in PCB technology, planar inductors can be realized in a single Cu layer on a PCB, and insulated from the environment using a cover layer of polymeric solder mask. This type of electrode structure can inductively couple with magnetic materials in close proximity to the sensor. A variety of magnetic materials exist, including iron, nickel and cobalt. Additionally, many alloys of these elements are also magnetic. Of particular interest are corrosion products with magnetic properties, such as iron(III) oxide, Fe3O2, also known as common rust. A thin layer of iron(III) oxide powder deposited on the sensor's active area results in a measureable increase in the sensor's inductance. As such, an inductive PCB sensor could be a low-cost option for detecting the presence of some corrosion products in its operating environment.

A Wireless Hay Bale Status Sensor Suite Using PCB Sensor Technology

2017 ◽  
Vol 2017 (DPC) ◽  
pp. 1-31
Author(s):  
Jeff D. Craven ◽  
Andrew W. Muscha ◽  
R. Chase Harrison ◽  
Markus A. R. Kreitzer ◽  
Robert N. Dean ◽  
...  
Keyword(s):  
Moisture Content ◽  
Spontaneous Combustion ◽  
Thermophilic Bacteria ◽  
Low Cost ◽  
The United States ◽  
Circuit Board ◽  
Sensor Technology ◽  
Moisture Content Level ◽  
Suitable Environment ◽  
Sensor Suite

The spontaneous combustion of curing hay bales poses serious safety and financial issues to farmers and ranchers across the United States and abroad. The primary cause of this spontaneous combustion is the baling of hay before it has adequately dried and reached a sufficiently low moisture content level. This inadequate drying is primarily due to the farmer allowing the hay to dry in the field after cutting for a given period of time. But unfortunately, this does not always ensure that the hay has sufficiently dried before baling. Spontaneous combustion of hay bales is due to a proliferation of thermophilic bacteria that thrive in a moist and hot environment. If the moisture content of hay is greater than 20%, it provides a suitable environment for mesophilic bacteria, which can heat the hay to as a high as 140°F. Although this is not problematic in and of itself, a 140°F hay bale is a suitable environment for the proliferation of thermophilic bacteria, which can further heat the hay to 170oF. At this temperature, the hay can spontaneous combust, destroying the hay and risking the loss of buildings, equipment, livestock and agricultural workers. To combat this problem, a low-cost, low-power, wireless hay bale status sensor suite has been developed so that the farmer can easily and safely monitor the conditions inside a curing hay bale, to give the farmer time to take action before the bale spontaneously combusts. The battery operated sensor suite has two sensors in contact with the hay inside the bale, a printed circuit board (PCB) moisture content sensor and a discrete temperature sensor. The extremely low-cost of the PCB moisture content sensor is what enables the practicality of the sensor suite. WiFi is used to transmit moisture content and temperature data to the farmer's smartphone when it comes within range. The sensor suite is placed inside the bale at the time of baling. After the bale has fully cured, in four to six weeks, the reusable sensor suite can be removed and used in a new bale.

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