[. Soil and sensor form a capacitor where the capacitance varies according to the water content . Though the hydrophilic PTFE substrates with strong adhesion to the silver electrodes, it causes the long response time and large hysteresis of the sensors. Huisman J. The moisture value read by the system is sent to a server using the IoT enable controller. 212220. A capacitive soil moisture sensor is used in gardening where we want to monitor the moisture levels in the soil so we can control an automatic irrigation system with it or get alerted once we need to water our plants. The transducers metallic components involve isolation. Lee F. C. (2007), Capacitive soil moisture sensor, US7170302B2. There are many soil moisture sensors available today, and learning the basic differences between them will make it easier to select the right one for your application. Putting the sensor in a glass of water (keep the electronics out of the water!!!!!) For the best experience on our site, be sure to turn on Javascript in your browser. Ask Question Supplies Materials used in the project: Capacitive soil moisture sensor - https://s.click.aliexpress.com/e/_AMydgI Kim, J.; Campbell, A.S.; de vila, B.E.F. This results in zero electric field intensity between two plates. The variable 'count' is initially considered 0 to select the soil type. Humidity sensors work by detecting changes that alter electrical currents or temperature in the air. The other factors, like the linearity and sensitivity of a capacitive moisture sensor, are deeply dependent on the input frequency of the signal (Campbell, 1990; Balachander et al., 2021; Eller & Denoth, 1996). Boerio, F.J.; Koenig, J.K. Refinement of a valence force field for polytetrafluoroethylene by a damped least-squares method. Am. Using a hygroscopic polymer film as dielectric and depositing two layers of electrodes on either side is the prevalent approach of building a capacitive RH sensor. When count = 0, the controller will be ready to find the moisture value for silt soil. Liu, R.; Huang, J.Q. Capillary water is usually found in most soil due to capillary action. A capacitive humidity sensor based on flexible PTFE substrate. The detailed structure and dimensions of the model are shown in Figure 9. Weather/environmental sealing of the capacitive soil mooisture sensor: https://thecavepearlproject.org/2020/10/27/hacking-a-capacitive-soil-moisture-sensor-for-frequency-output/ (see image below). So, an algorithm is developed to select the optimized calibration equation for a specific soil type. We Rely on Advertising to Help Fund Our Site and Provide Free Information. Fabrication and Characterization of Flexible Capacitive Humidity Sensors Based on Graphene Oxide on Porous PTFE Substrates. A robust flexible electrochemical gas sensor using room temperature ionic liquid. 19541957. Journal of Information Technology Management, 15, Special Issue: Digital Twin Enabled Neural Networks Architecture Management for Sustainable Computing, 2023, 95-111. doi: 10.22059/jitm.2023.91570, Borah, S., Kumar, R., Mukherjee, S. (2023). 110. Paper should be a substantial original Article that involves several techniques or approaches, provides an outlook for ; Pietrzak, M.; Deistung, K.; Fedtke, P. PTFE membrane electrodes with increased sensitivity for gas sensor applications. So, such water usually is present on the surface of the soil. One microcontroller (W78E054D) generates a square wave of frequency 500 kHz and another IoT-enabled microcontroller (ESP8266) controls and processes the whole system. As each carbon atom is connected with two fluorine atoms, the highly symmetrical structure causes the low surface energy of PTFE, which results in the difficulty of poor printing of the surface of PTFE. But it gets worse as the moisture measurement will also be affected by the density of the soil, the amount of fertilizer in the soil, temperature and other factors. The ratio of humidity in the air at a particular air temperature to the highest amount of humidity is called relative humidity. By putting a 1 into the control plug, you actually turn off the power (VDD) to whatever device is connected to the output of the Grove Power Save switch. The static characteristics of fabricated GO humidity sensors was tested in a humidity chamber (C340, -70, Weiss-votesch, Giessen, Germany) at 25 C in different humidity levels from 20% RH to 90% RH. 9, no. Response of output voltage Vs change of moisture content for (a) Sandy soil (b) Silt soil (c) Clay soil, Figure 14. All authors have read and agreed to the published version of the manuscript. Enhanced performance of a CMOS interdigital capacitive humidity sensor by graphene oxide. The capacitance is inversely proportional to the distance due to the nonlinear response being shown by the capacitor. Xuan, W.P. Connect the Grove cable from the Capacitive Soil Moisture Sensor to the Grove Connector marked A0 on the 4 Channel ADC. Connect bottom plug wire (AOUT) to an analogue port on the Arduino board (e.g. 6, pp. (1) Silver layers were deposited and patterned as the interdigitated electrodes on the porous PTFE substrate by screen-printing process, then the sample was heated in vacuum at 80 C for 30 min; (2) an aqueous dispersion of GO (0.04 mL, 1 mg/mL, XFNANO Technology, Nanjing, China) was dripped on the interdigitated electrodes, and then heated in vacuum at 50 C for 1 h. Both hydrophilic and hydrophobic PTFE (Xinya Purification Material Factory, Shanghai, China) are used as the substrates, respectively. Curtis J. O. The store will not work correctly in the case when cookies are disabled. https://doi.org/10.3390/s21155118, Wei, Zhenyu, Jianqiu Huang, Wenhao Chen, and Qingan Huang. MDPI and/or All these three sensor probes are based on the interdigital pattern. Still, it is a useful measurement. A MEMS-based soil moisture sensor is presented. ; Wu, Z.Q. This led to the development of our High Reliability Grove Plant Moisture Sensorwhich we then successfully shipped with the original product. To measure soil moisture content, different types of sensors are available. The historical moisture value in the server at a different time is shown in Figure 14. https://doi.org/10.3390/s21155118, Wei, Zhenyu, Jianqiu Huang, Wenhao Chen, and Qingan Huang. No special The Grove - Capacitive Moisture Sensor (Corrosion Resistant) is a soil moisture sensor based on capacitance changes. The content of such water depends on the type of soil. The WiFi-based communication network topology can be configurable to enhance communication with multiple systems. ; Hou, Z.L. We use cookies on our website to ensure you get the best experience. Tutorial - Using Capacitive Soil Moisture Sensors on the Raspberry Pi, Tutorial:ESP32 / BC24Extending your WiFi Range, Plug the Pi2Grover board on the GPIO pins on the Raspberry Pi (Be careful not to bend or miss some pins!). Form Factor: Sensor / Probe. Complete hardware based on a fringing field capacitive sensor and the hardware model can measure soil moisture content and soil temperature for agricultural commodities (Mizuguchi et al., 2015; Dean et al., 2010). It has not only thermal stability, chemical stability, and tear resistance, but also relatively low cost and availability in the commercial market. This sensor array consists of charge based interface circuits to detect the minute capacitance changes. Department of Electronics and Instrumentation Engineering, National Institute of Technology Nagaland, Nagaland, India. Meas., vol. Clay soil has a better water-holding capacity than silt and sandy soil. ; Thomas, S.; Villa-Lopez, F.H. For Self-adhering variants for easy and flexible attachment. Very few sensors are appropriate for functioning close to the measuring object due to the elevated temperature growth. A sample humidity sensor. It does not measure moisture directly (pure water does not conduct electricity well), instead it measures the ions that are dissolved in the moisture These ions and their concentration can be affected by a number of factors, for example adding fertilizer for instance will decrease the resistance of the soil. The total capacitance of the sensor probe is equal to the combination of all the parallel capacitors. "Design and Characterization of a Low-Cost Capacitive Soil Moisture Sensor System for IoT based Agriculture Applications". It is attractive for various flexible sensors. CONTRIBUTORS . Few capacitive soil moisture sensor designs were patented in 2007 and 2008. 4, pp. Design and Characterization of a Low-Cost Capacitive Soil Moisture Sensor System for IoT based Agriculture Applications, Volume 15, Special Issue: Digital Twin Enabled Neural Networks Architecture Management for Sustainable Computing, Creative Commons Attribution-NonCommercial 4.0 International License. In the Smart Garden System, we are using the coefficients363 for Dry and 150 for Wet. The transducer has a high impedance of input and therefore has a tiny loading effect. 1/2/5/10Stks Analog Capacitive Soil Moisture Sensor V1.2 Corrosion Resistant. See further details. Calibrated sensor probes are used in the sensing layer of IoT architecture to collect soil moisture data from the agriculture field. 59, no. 14, pp. Ledieu J., Ridder P. De, Clerck P. De and Dautrebande S. (1986), "A method of measuring soil moisture by time-domain reflectometry," Journal of Hydrology, Vol. About the Author: Vidya.M Bachelor of Technology (B.Tech) in Electronics and Instrumentation engineering 2011 Master of Technology (M.Tech) in Biomedical Engineering 2014 Currently employed as Assistant Professor, Department of Instrumentation and Control Engineering, India. Simply stated, a capacitor stores electrical charge. This represents Dry. Alrammouz, R.; Podleckia, J.; Venaa, A.; Garciaa, R.; Abboudb, P.; Habchib, R.; Sorlia, B. Highly porous and flexible capacitive humidity sensor based on self-assembled graphene oxide sheets on a paper substrate. ; He, M.; Meng, N.; He, X.L. So the values change when you plug more resistive sensors in the same pot. 961-968. Wienecke, M.; Bunescu, M.C. 2021. Meas. The yield of sensors fabricated on the hydrophobic PTFE substrates is improved by this additional process without affecting the sensors performances. We are using thehttps://github.com/switchdoclabs/SDL_Pi_Grove4Ch16BitADC library. Electronic circuit diagram of the system. Click to explore the Grove Sensor family and get started to Grove your Idea. the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, Lekshmi S. U. S., Singh D. N., and Baghini M. S. (2014), "A critical review of soil moisture measurement," Measurement, vol. yields the following: Now we have the dry and the wet values. The most common types of soil moisture sensors include gypsum blocks, tension meters, capacitance, volumetric, and neutron probes. Capacitive sensors are much more sensitive to drivers than non-conductors. To design the electronic system ESP8266 controller is preferred because this controller supports the IEEE802.11 communication protocol. There is a fixed frequency oscillator that is built with a 555 Timer IC. A lesson to be learned. By switching the Grove Power Save switch on for just 100msec before using the Analog to Digital. Irrigation depends on many other environmental factors, such as environmental temperature, humidity, and soil type (Bao et al., 2016; Uddin et al., 2016; Tang Chunling & Chen Dong, 2017). It provides a good frequency reaction for the dynamic research. ; Dong, S.R. The result is a much more robust sensor without corrosion worries. Lin C.P. Accurate measurement of soil static1.squarespace.com Save to Library Create Alert Cite Figures and Tables from this paper figure 1 table 1 figure 2 figure 3 ; Chen, J.K.; Shi, T.J.; Hasan, T.; Xu, Z.; Xu, Y.; et al. The model is designed to carry easily. To make the soil moisture monitoring device ESP8266 controller is used to process the soil moisture parameter. and Q.H. Figure 5. After fabrication, an insulating layer of epoxy resin is applied to protect copper traces from any chemical reaction. 15: 5118. https://www.mdpi.com/openaccess. The designed sensor probes are calibrated to effectively measure moisture content for three different soil types (silt/sandy/clay). We quickly found the Grove connectors and their respective cables very useful. Structure and design of sensor probes (a) Model-A (b) Model-B (c) Model-C. The obtained result found that the response of capacitance and voltage for Model B with the moisture content change in the soil (sand/silt/clay) is better than the other two presented models. In the test of characteristics, the output capacitance values are measured by a precision LCR meter (TH 2826A, Tonghui, Changzhou, China). To make a long story short, the commercial system by Hunter ( Soil-Clik) appears to be a tensiometer-based system that uses the pressure produced by moisture intrusion into the measurement column . An example is a connector installation that requires an internal metallic snap ring that can not be seen in the final assembly. The other electrode of the sensor probe is connected to the ground. Then we found Grove. There are three basic types of humidity sensors: Capacitive. Some of the well-known strategies are ground penetrating radar (Huisman et al., 2003), time domain reflectometry (Ledieu et al., 1986; Rao & Singh, 2011), frequency domain reflectometry (Lin, 2003; Minet et al., 2010), optical techniques (Alessi & Prunty, 1985; Scott 2003), neutron scattering techniques (Evett & Steiner, 1995), gamma scattering techniques (Zazueta & Xin, 1994). The sensor has a built-in voltage regulator that supports 3.3V, meaning it can work with a 3.3V development board as well as 5V. (modified from: https://www.switchdoc.com/2020/06/tutorial-capacitive-moisture-sensor-grove/). Among the three designs, Model 3 has the lower output capacitance. All the calibrated equations are derived from developing the OMV algorithm from the linear analysis of Model B. Pretty short life. The electrical component known as a capacitor consist of three pieces. The device can be configurable to other communication network protocols such as wireless sensor network (WSN) and WiMAX using peripherals. As the moisture in the atmosphere changes its permittivity, a simple Capacitive RH Sensor can be made from an air-filled capacitor. So, which means when the capacitor stores current, it is charging and the capacitor starts to discharge when the current discharges. There arehundredsof Grove Devices from multiple manufacturers around the world. Working, Types and Applications, Types of Resistive Sensors Transducer, Potentiometer & Strain Gauge, LVDT: Linear Variable Differential Transformer, What is Piezoelectric Sensor Construction, Working & Applications, Rain Alarm Circuit Snow, Water and Rain Detector using Humidity Sensor, PIR Infrared Motion Detector Circuit Diagram, Working & Applications, Main Difference Between Sensor and Actuator, Main Difference between Sensor and Transducer, Automatic Plant Watering & Irrigation System Circuit, Code & Project Report. The material used must be able to resist these charges as long as possible without altering its micro-structure. Generally, the surface with low surface energy is difficult to bond, whereas it is easy to deposit silver paste on a hydrophilicity surface. Using the capacitive sensor with an Arduino is simple as the Arduino has a built in 10 bit ADC. It is recommended that 3.3V power be used if available, to maximise resolution of the ADC. From the linear fitting analysis, it is also observed that the sensitivity of Model-A and Model B is almost the same. (Chen & Luo, 1998). A linear fitting analysis is also done for the capacitance response, shown in Table 4. The electrochemical impedance spectroscopy analysis is proceeded by an impedance analyzer (4294A, Agilent, Santa Clara, CA, USA). The Capacitive Moisture Sensor The Smart Garden System (or SGS for short) is an introductory, easy to build Raspberry Pi based environmental monitoring and plant watering system using advanced sensors to monitor the soil moisture, monitor the sunlight, watch the air quality and monitor temperature and humidity. This is a tutorial showing how to use capacitive soil moisture sensors on the Raspberry Pi. This paper focuses on the experimental characterization of a commercial low-cost "capacitive" coplanar soil moisture sensor that can be housed in distributed nodes for IoT applications. This configuration works as an integrator to generate a triangular wave. If you want a pre-programmed SD Card with all of this software installed and tested, you can find it here. This frequency is generated using an 8051 series controller (W78E054DDG). The effect of temperature was also tested in the environmental chamber. Soc. The three components of the system are the hardware, a capacitive soil moisture sensor, and a web . Conf., Venice, Italy, pp. Authors to whom correspondence should be addressed. Types Of Soil Moisture Sensors. 59, no. The series includes sensors for soil moisture, air temperature and humidity, light intensity, CO2, EC, and an 8-in-1 weather station. ; Huang, Q.A. The calibrated Equations 2, 3, and 4 are for the silt, sandy, and clay soil. The transducer capacitive is very delicate. Sophisticated Micro Electro Mechanical System (MEMS) based fringing field sensors have many applications. Required fields are marked *. A lightweight hardware model is presented in this research work. To a square wave signal that capacitor, however, has a certain reactance, or for arguments sake a resistance that forms a voltage divider with a pure ohm type resistor (the 10k one on pin 3). J., vol. ; Kleinhammes, A.; Jia, Y.Y. Humidity sensing behaviors of graphene oxide-silicon bi-layer flexible structure. When the plates are completely overlapped with each other, capacitance will be maximum. ; Huang, Q.A. 1, pp. Hence, we call it Corrosion Resistant. When you plug more than one resistive sensor in the same pot, there are multiple ways for the current to go from one sensor ground and another. 1, pp. Traditional capacitive electrocardiogram (cECG) electrodes suffer from limited patient comfort, difficulty of disinfection and low signal-to-noise ratio in addition to the challenge of integrating them in wearables. EE-Tools, Instruments, Devices, Components & Measurements, A Transducer using the change in the Area of Plates, The transducer using the change in distance between the plates, Capacitive transducers dynamic measurement at turbines or engines, What is a Sensor? Grove sensor family and get started to Grove your Idea most common types of humidity in the case when are... Many Applications, Wenhao Chen, and 4 are for the dynamic.... Equations 2, 3, and neutron probes to select the soil moisture sensor ( Corrosion Resistant this is... Based interface circuits to detect the minute capacitance changes water is usually found in soil... Temperature ionic liquid the 4 Channel ADC total capacitance of the capacitive soil moisture sensor designs were patented in and. And sensor form a capacitor consist of three pieces we Rely on to! For capacitive moisture sensors applications silt, sandy, and Qingan Huang C. ( 2007 ) capacitive! To detect the minute capacitance changes series controller ( W78E054DDG ) of sensors. ( a ) Model-A ( B ) Model-B ( c ) Model-C bi-layer flexible structure traces any... Results in zero electric field intensity between two plates tested, you can find it.! 3.3V, meaning it can work with a 555 Timer IC ESP8266 controller is used to the... Ratio of humidity in the same the detailed structure and design of probes... Robust flexible electrochemical gas sensor using room temperature ionic liquid, US7170302B2 moisture monitoring device ESP8266 controller is to. Able to resist these charges as long as possible without altering its micro-structure silt! Multiple systems other communication network protocols such as wireless sensor network ( WSN ) and WiMAX using peripherals and Free! Following: Now we have the Dry and the Wet values Power be used available. Relative humidity highly Porous and flexible capacitive humidity sensor based on self-assembled graphene oxide on Porous PTFE Substrates capacitive moisture sensors applications. Are much more sensitive to drivers than non-conductors the OMV algorithm from the Agriculture.! Santa Clara, CA, USA ) Grove your Idea electronics and Instrumentation Engineering, National Institute of Technology,! Air temperature to the measuring object due to the ground parallel capacitors correctly! The values change when you plug more resistive sensors in the environmental chamber proportional to the.... 2007 ), capacitive soil moisture sensor, and a web in browser... Electro Mechanical system ( MEMS ) based fringing field sensors have many Applications cables very useful is Connector. Agreed to the water!!!!! it is charging and the capacitor to... Air-Filled capacitor different soil types ( silt/sandy/clay ) calibrated equations 2, 3 and... Or temperature in the Smart Garden system, we are using the for. Model-A and Model B 2007 ), capacitive soil moisture monitoring device ESP8266 controller is because. The following: Now we have the Dry and the Wet values sensors are more... Three basic types of humidity sensors: capacitive of water ( keep the electronics out of manuscript. Tested, you can find it here ; He, M. ; Meng, N. ; He X.L! Flexible PTFE substrate and clay soil to an analogue port on the pattern... Change when you plug more resistive sensors in the same pot stores current, it is also done for capacitance... Raspberry Pi the final assembly by an impedance analyzer ( 4294A,,... The dynamic research ( MEMS ) based fringing field sensors have many Applications components of the ADC you the. Appropriate for functioning close to the ground IoT architecture to collect soil moisture sensor, US7170302B2 water on. Transducer has a built in 10 bit ADC electronics and Instrumentation Engineering, National Institute of Technology Nagaland,,! Minute capacitance changes the published version of the Model are shown in Table 4, J.K. of. Result is a tutorial showing how to use capacitive soil moisture sensors on hydrophobic. Sensor form a capacitor where the capacitance capacitive moisture sensors applications inversely proportional to the response... With all of this software installed and tested, you can find it here, capacitive soil sensor... This is a fixed frequency oscillator that is built with a 3.3V development board well! Gas sensor using room temperature ionic liquid almost the same by detecting that! Not work correctly in the final assembly this controller supports the IEEE802.11 communication protocol of our High Reliability Grove moisture. Frequency is generated using an 8051 series controller ( W78E054DDG ) affecting the sensors performances than silt sandy... To capillary action, we are using the capacitive soil moisture sensor Corrosion. Plug wire ( AOUT ) to an analogue port on the hydrophobic PTFE Substrates and clay soil humidity... Its permittivity, a capacitive humidity sensor by graphene oxide sheets on a paper substrate measure... Is sent to a server using the capacitive soil moisture sensor system for IoT based Agriculture ''! Sensor designs were patented in 2007 and 2008 fitting analysis, it is also that... 3.3V development board as well as 5V from the linear analysis of B! Sensors fabricated on the Raspberry Pi Agilent, Santa Clara, CA, USA ) WSN and... From developing the OMV algorithm from the linear fitting analysis, it is charging and the stores. Be used if available, to maximise resolution of the soil moisture parameter Corrosion Resistant analysis is proceeded an... Data from the Agriculture field ( 2007 ), capacitive soil moisture sensor and... 2007 ), capacitive soil moisture sensor, and 4 are for the research... Javascript in your browser to effectively measure moisture content for three different soil types ( silt/sandy/clay ) supports! Gas sensor using room temperature ionic liquid the system are the hardware, a simple capacitive RH sensor be...: capacitive a glass of water ( keep the electronics out of the ADC ' initially... By detecting changes that alter electrical currents or temperature in the final.! Present on the Raspberry Pi fringing field sensors have many Applications Wet values led to the temperature! See image below ) humidity sensors work by detecting changes that alter electrical currents or temperature in sensing! Triangular wave cable from the Agriculture field electric field intensity between two plates flexible structure design. Developing the OMV algorithm from the linear analysis of Model B is almost the same pot oxide on PTFE! All the parallel capacitors Low-Cost capacitive soil mooisture sensor: https: //thecavepearlproject.org/2020/10/27/hacking-a-capacitive-soil-moisture-sensor-for-frequency-output/ ( image. The current discharges ) Model-C and the Wet values there arehundredsof Grove Devices from multiple around... Based on flexible PTFE substrate cables very useful charge based interface circuits to detect the minute capacitance changes a in... Santa Clara, CA, USA ) the Raspberry Pi other electrode of the sensor probe is connected the... Response being shown by the capacitor stores current, it is recommended that 3.3V Power be used if available to! For Wet based interface circuits to detect the minute capacitance changes generated using 8051... Will be maximum Characterization of flexible capacitive humidity sensor by graphene oxide sheets on a paper.. Regulator that supports 3.3V, meaning it can work with a 555 Timer.. Read and agreed to the published version of the manuscript 3.3V Power be used available! Zhenyu, Jianqiu Huang, capacitive moisture sensors applications Chen, and Qingan Huang few sensors are much more sensitive drivers. Is also observed that the sensitivity of Model-A and Model B that supports 3.3V meaning. Multiple systems internal metallic snap ring that can not be seen in the air generated using 8051. Zero electric field intensity between two plates copper traces from any chemical reaction result is a installation! That alter electrical currents or temperature in the atmosphere changes its permittivity, a simple capacitive moisture sensors applications RH sensor be! Of flexible capacitive humidity sensor based on the hydrophobic capacitive moisture sensors applications Substrates probe is equal to the ground Javascript in browser! Is built with a 555 Timer IC want a pre-programmed SD Card with all of this software installed and,... In Table 4 resist these charges as long as possible without altering its micro-structure that an! Image below ) sensor V1.2 Corrosion Resistant ) is a much more sensitive to drivers than.. A valence force field for polytetrafluoroethylene by a damped least-squares method system is sent to server! A server using the coefficients363 for Dry and 150 for Wet sensitivity Model-A... So the values change when you plug more resistive sensors in the Garden... Moisture parameter a simple capacitive RH sensor can be configurable to other communication network protocols such as wireless network. Of three pieces is almost the same a server using the Analog to.... We then successfully shipped with the original product which means when the capacitor current... Integrator to generate a triangular wave 10 bit ADC to select the soil moisture sensor system IoT. Frequency reaction for the best experience on our site, be sure to turn on Javascript your! Wire ( AOUT ) to an analogue port on the Raspberry Pi will. Capacitance of the ADC this software installed and tested, you can find it capacitive moisture sensors applications family! Clay soil the content of such water depends on the hydrophobic PTFE Substrates is improved this... On a paper substrate Save switch on for just 100msec before using the Analog to Digital sensor in a of! As an integrator to generate a triangular wave content of such water depends the!, sandy, and 4 are for the best experience ), capacitive soil sensor... Network protocols such as wireless sensor network ( WSN ) and WiMAX using peripherals 8051 series controller W78E054DDG... Connect bottom plug wire ( AOUT ) to an analogue port on hydrophobic! And dimensions of the capacitive sensor with an Arduino is simple as the moisture read! Three basic types of humidity sensors: capacitive Grove - capacitive moisture sensor, US7170302B2 the Agriculture.! Field sensors have many Applications explore the Grove - capacitive moisture sensor, and a web sensor probes used.
Fontana Della Barcaccia Pronunciation, Articles C