Once students have successfully run the code, expect them to see the LCD power on and display the text: Rel Conductance. Calibrating the correction factor is a bit more work. Integrate a conductivity probe into a simple circuit. Once groups have completed recording their results in Data Table 1 of the handout for Part 2, make sure they save their solutions for use later in Part 3. Use appropriate symbols, numbers, and words to communicate key ideas about technological products and systems. 8), Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials, time, or cost. We regret that this curriculum does not meet your expectations. Set the baud rate to 9600 and select "Carriage return". A system to maintain the pH level of a sample within a defined range. Operation is via I2C protocol and readings are displayed on the Arduino serial monitor. Direct groups to collect the materials to complete Part 1, which are listed on page 3 of the handout. Then review and discuss students' responses to the questions to make sure they understand the role of the probe, its real-world applications and the types of substances that the probe helps to identify as being present or absent within solutions being analyzed. solute: The minor component in a solution, dissolved in the solvent. The less oxidation, the better. Thanks!! Calibrate the sensors. Calibrating was done by taking multiple samples of demineralised water and adding different amounts of salt to them. Once students have finished answering the questions, review their responses as a class before starting the lab activity, as described in the Assessment section. 12), laptop or desktop computer with USB cable and Internet access, 2 x 20 cm lengths of 22 gauge single-strand insulated copper wire; available at hardware stores, 2 x 10 cm lengths of 32 gauge nichrome wire; such as from, plastic barrel from a disposable pen, such as a BIC pen, four plastic cups, for the four test solutions, half-size or larger breadboard, such as the reasonably priced boards at, assorted jumper wires, such as a pack of 30 7-inch wires (PRT-11026) at, 470 resistor, such as the resistor multipacks at, red LED, such as the basic red 5 mm LED (COM-09590) at, 2 x 9V battery connector, such as the heavy-duty 9V snap connectors at, 16 x 2 LCD display, such as the basic 16-character by 2-line display with black text on green background (LCD-00255 ROHS) at, 10K trimpot (aka trimming potentiometer, a small variable resistor), such as the trimpot 10K with knob (COM-09806) at, 10K resistor, such as the resistor multipacks at, 220 resistor, such as the resistor multipacks at, soldering iron(s), such as the reasonably priced solder at, lead-free solder, a few tubes to share among one class, such as solder available at, wax pencil or tape and marker, to label the cups, distilled water, expect 1 gallon to be enough for an entire class, paper towels, for drying the rinsed probes, additional supplies may be needed to enable students to use their conductivity probes to conduct end-of-activity experiments of their own designs, for example, solutions of common household chemicals, lemon juice, sodium hydroxide, ammonia, at varying concentrations and temperatures, How to use a breadboard to construct simple circuits, Be able to identify the LED, resistor, jumper wire and related electrical components used in the activity, Aqueous solutions, including how to make a simple solution, Basic lab safety for conducting experiments in a chemistry laboratory. It also measures temperature to compensate for temperature changed resistance. Free K-12 standards-aligned STEM curriculum for educators everywhere. I'm going to try it out. See a few example discussion questions in the Assessment section. Next, students complete the "analyzing" section of the lab activity, composed of an online reading about electrolytes and nonelectrolytes, including a six-minute video, followed by an online digital experiment to test their reading comprehension. Students are introduced to the technology of flexible circuits, some applications and the photolithography fabrication process. 9 - Now to we add a button to start a measurement. Alignment agreement: Use electrical tape to cover the entire probe, with the exception of the 1 mm gap near the tip; see Figures 7 and 8). On your computer, open the Arduino IDE (You can download the IDE from, if you do not have it). After this activity, students should be able to: Each TeachEngineering lesson or activity is correlated to one or more K-12 science, This requires groups to design additional experiments that utilize their conductivity sensors. You will have to add them to your Arduino IDE in order to use the code. It consists of two parts. It has everything to do with conductivitythe ability of a solution to conduct electrical current. It also includes a simple embedded model of a conductivity sensor setup and five questions for students on the topic of electrolyte solutions and conductivity. Design a solution to a complex real-world problem, based on scientific knowledge, student-generated sources of evidence, prioritized criteria, and tradeoff considerations. - Breadboard, welding clamps or perfboard, - Three resistors (10k Ohm, 1k Ohm and 4.7k Ohm), - Temperature sensor (for example DS18B20 waterproof), - Two copper electrodes (like nails or pins), - LCD display for Arduino (for example I2C). The easiest way to do this is by taking hot water and measuring the resistance while it cools down. Pass out the handouts and direct students to individually answer the four "preparing" questions on page 2. In a hands-on activity, students build a conductivity tester to determine whether different objects are conductors or insulators. Also, I'm not worried about rusting or long term effects from electrolysis because the water is not used for plants or drinking or anything like that. (Grades (Grades The Arduino and wiring were put in a protective box for plugs. Its what has been used for ever to measure salinity. I tried doing both options, but couldn't get a change in the reading as I added salt to the test tank. Minimum programming skills needed unless you plan on modifying the project. In this lab activity, we will make a probe to use as a tool to determine very quickly whether a solution conducts electricity (ZAP!!) Since the measured resistivity could not immediately give the salinity level of the water, it is required to calibrate the sensor. They see the value of NDE and FEM Students learn about current electricity and necessary conditions for the existence of an electric current. Look for common circuitry mistakes related to the LED. They enter the code provided on the handout (or copy/paste the code if a digital version of the handout is made available). Plan and conduct an investigation individually and collaboratively to produce data to serve as the basis for evidence, and in the design: decide on types, how much, and accuracy of data needed to produce reliable measurements and consider limitations on the precision of the data (e.g., number of trials, cost, risk, time), and refine the design accordingly. The higher the conductivity of a solution, the less resistance to the flow of electrical current. Question Though both measurements are for the same solution, the means of communicating conductivity [light in Part 2 and a numerical measurement display in Part 3] are very different. The serial monitor will open. Example discussion questions: When soldering the wires in Part 1, require students to wear safety glasses and be sure they know that a soldering iron is extremely hot, even for several minutes after it is unplugged. Alternatively, you may provide students with the. It was not tested on Mac, Atlas Scientific does not know if these instructions are compatible with a Mac system. Have groups proceed to follow the handout instructions to each make two solutionssalt water and sugar water. Determine the conductivity of an unknown solution. This is only for visuals). Any other thermometer can be used, but in this guide only the wiring for the DS18B20 will be provided. This was a project for the minor Delta Expert at the Delft University of Technology. The. With the StudentsIntroduction/Team Formation, With the StudentsPart 1: Constructing the Probe, With the StudentsPart 2: Testing the Probe, With the StudentsPart 3: Connecting the Probe to the Arduino, With the StudentsPart 4: Critical Thinking and Analysis. The calibration and the switch to I2C MUST be done before implementing the sensors into this project. Use of the TeachEngineering digital library and this website constitutes acceptance of our Terms of Use and Privacy Policy. Refer to the following: Ezo pH datasheet, Ezo EC datasheet. For example, desalination facilities use conductivity measurements to ensure that water samples have been sufficiently purified. Refer to the following: Set sensors' protocol to I2C. This lab activity requires students to make simple solutions by dissolving various solutes into measured volumes of water. How to make a benchtop pH meter with an Arduino Uno and the Gravity analog pH sensor from Atlas Scientific. Fundamentally, the probe measures the resistance to the flow of charge and must be submerged within the testing solution to work. https://thecavepearlproject.org/2017/08/12/measuring-electrical-conductivity-with-an-arduino-part1-overview/. The code for this project makes use of a customized library and header file for the EZO circuits in I2C mode. In the second experiment, the feedback comes in the form of a digital numerical readout (constituting a quantitative measurement) in which, as the numerical value displayed increases, the conductivity of the solution increases. That's because the circuit is a actually voltage divider right? Some NaCl (salt) is added to the water, the conductivity reading rises and as soon as it crosses 500S/cm the yellow LED turns on. If yes then I just picked up on that :P, Press J to jump to the feed. HS-PS1-3. Afterwards, you will build on your understanding of how the conductivity probe works to design and conduct an experiment of your own. Do you agree with this alignment? In the IDE, go to Sketch -> Include Library -> Add.ZIP Library -> Select the Ezo_I2c_lib folder you just downloaded. Make sure they are tighly glued or fixed in place. Proofread (and modify as necessary) all proposed procedures before permitting groups to proceed to conduct their designed lab experiments. http://www.fivecreeks.org/monitor/sal.shtml. 6 - This is however not always correct. Let's start with the resistivity sensor. The resistance was measured. Examples of what students might test: Monitor conductivity while an acid is added to a base, such as lemon juice added to a dilute solution of sodium hydroxide or ammonia. Set the baud rate to 9600 and select "Carriage return". 3 months ago, Arduino Robotic Arm Controlled by Touch Interface. Next, twist one of the nichrome wires onto the exposed copper end of one of the insulated wires. The steps below include the process of making this addition to the IDE. within type by subtype, then by grade, etc. Thanks for your feedback! Since this sensor will be used in water, it is important to shield all electrical components from the water. Real time plant monitoring system to view temperature, light exposure and moisture. Do you agree with this alignment? Thanks for your feedback! Operation is via I2C protocol and readings are displayed on the Arduino serial monitor. The initial pH and EC of water are measured. c) Copy the code from pH_EC_led_indicator onto your IDE work panel. or not. The electrodes were put in a black plastic casing with two holes in the front and one in the back. You can use either an Arduino UNO or a STEMTera board. Different patterns may be observed at each of the scales at which a system is studied and can provide evidence for causality in explanations of phenomena. Conductive solutions always result from the presence of a solute that is ionic, meaning it dissociates in water into charged particles called ions. During the activity, students require access to the following Internet resources: In addition, the CK-12 Foundation has an excellent little web app that serves as an appropriate follow up for students after completing the activity. The probe measures resistance and translates the resistance as an indicator of conductivity. Plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles. They are challenged to determine if the fabrication process results in a change in the circuit dimensions since, as circuits get smaller and smaller (nano-circuits), this c Students learn about nondestructive testing, the use of the finite element method (systems of equations) and real-world impacts, and then conduct mini-activities to apply Maxwells equations, generate currents, create magnetic fields and solve a system of equations. Our sensor was already calibrated, so will not discuss calibrating the thermometer in this guide. Then the two wires are taped onto opposite sides of the pen barrel. To avoid electrolysis we put an AC current over the electrodes. Note that we use a "known" resistance which is being used to measure the "unknown" resistance of the water. I would have expectd PPT, but I'm sure thats not the unit. Looks like a fun project. In this project, we will be making a pH and salinity/conductivity monitoring system with LED indicators. For this we need the following: Since the aim is to measure seawater, we want to avoid electrolysis which makes the electrodes oxidize and that in turn will make the resistance increase rapidly over the first second of the measurement. b) Set sensors' protocol to I2C. isolates the pH circuit from the salinity circuit, thus protecting it from any electrical interference (noise) that may originate from the salinity sensor or other electronics in the system. The 220 resistors limit the current to the LEDs, preventing them from blowing out. The correction factor generally lies between 2-4% change in resistance for each degree temperature change. Can you please tell me the units the salinity is displayed in? probe: A small device, especially an electrode, used for measuring, testing or obtaining information. Do you agree with this alignment? The appropriate files are now included. However, if the solution contains only water molecules or a solution of water and other covalent solutes, no charged particles exist to facilitate the flow of charge so the resistance across the probe will be very high. For information on how to change between protocols and assign addresses, refer to this. Review what is necessary in order to form a solution, that is, a solute dissolved into a solvent. In accordance with the sample code for this project, the following addresses are used: pH sensor address is 99, and salinity sensor address is 100. Criteria may need to be broken down into simpler ones that can be approached systematically, and decisions about the priority of certain criteria over others (trade-offs) may be needed. If you are always getting the same reading, then perhaps you should fine tune the resistor and/or the distance between the electrodes to improve your sensibility. Set-up student lab stations with the supplies necessary for each group. Once the circuits are checked by the teacher, students test their probes by immersing them into cups of four different solutions: salt water, sugar water, distilled water and tap water. You know your correction factor is correct when the "Corrected resistance" does not change while the water cools down. 5 weeks ago. This equipment is intended for electrical engineers. Following the handout instructions, groups each create a simple circuit using a breadboard, LED, 470 resistor, 9V battery with wires and some jumper wires. Do NOT correct student predictions at this point.). From the reading you already have now, try to calculate the resistance between the electrodes. During this final component of the lab activity, students work together to complete the "critical thinking" portion of the lab activity as presented on the handout. The structure and interactions of matter at the bulk scale are determined by electrical forces within and between atoms. conductivity: The degree to which a specified material conducts electricity, calculated as the ratio of the current density in the material to the electric field that causes the flow of current. Then they answer three handout questions. The measurement of conductivity is typically a measure of how easily electrical current is able to move through a solution. I think the sensor would last long enough before having to change its probes as I'm gonna have its voltage source enabled only when a reading is needed. Identify whether a solution is conductive. The Inline Voltage Isolator isolates the pH circuit from the salinity circuit, thus protecting it from any electrical interference (noise) that may originate from the salinity sensor or other electronics in the system. In accordance with the sample code for this project, the following addresses are used: pH sensor address is 99, and salinity sensor address is 100. If you are not familiar with electrical engineering or embedded systems programming, these products may not be for you. Each sensor has a unique calibration process. From one side the power cable could be let in and from the other side the electrodes and thermometer cables could be let out. As students begin Part 3, each group uses a computer connected to an Arduino UNO to upload its codes to the Arduino. Chemistry, Science and Technology, Students use an Arduino UNO, a breadboard and a LCD display to create a simple conductivity probe.copyrightCopyright 2015 Phillip Cook, Polytechnic Institute of NYU. I'm trying to make a sensor to measure the salinity in a water tank. The STEMTera board was used in this project for its compact design where the Arduino is combined with the breadboard. Reply A HIGH pin will be the positive and a LOW pin will be the negative. solution is added and the pH decreases. Through this lab, students are exposed to multiple ways that a conductivity probe can be used and challenged to consider its possible real-world applications. Each sensor needs a unique I2C address. A solution conducts electrical current when charged particles (ions) are in the aqueous solution. For information on how to change between protocols and assign addresses, refer to this LINK. It is the reciprocal of the resistivity. Rember it must be close to the resistance of the resistor you have in the circuit. nonelectrolyte: A substance that does not readily ionize when dissolved or melted and is a poor conductor of electricity. *The NGSS logo is a registered trademark of WestEd. The serial monitor will open. We are glad that this curriculum met your expectations. (Grades 9 - 12). Depending upon the solute, the resulting solution will either conduct electricity or be non-conductive.
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