Difference between revisions of "Team:NCKU Tainan/pH meter"

 
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     <!--Page_Content-->
 
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     <div class="container content">
 
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        <h1 class="head">pH Meter</h1>
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            <div class="headstyle">
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                <h1 class="head">pH Meter</h1>
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            </div>
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            <div class="righttitle">
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                <h6 class="subtitle"></h6>
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                     <div data-spy="scroll" data-target="#sidelist" data-offset="0" class="scrollspy-example">
 
                         <div class="container">
 
                         <div class="container">
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<img class="contentimg col-12" src="https://static.igem.org/mediawiki/2018/f/f2/T--NCKU_Tainan--pH_sensor.jpg">
 
                             <p class="pcontent">
 
                             <p class="pcontent">
 
                                 About this section, we are showing how to use the pH meter in arduino.
 
                                 About this section, we are showing how to use the pH meter in arduino.
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                                         value of
 
                                         value of
 
                                         6, and
 
                                         6, and
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                                         generally grow the best about pH 7.
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                                         generally grow the best at pH 7.
 
                                     </p>
 
                                     </p>
 
                                 </div>
 
                                 </div>
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                                         <ul>
 
                                         <ul>
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                                             <li>Because the buffer solution wouldn’t change too much in the
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                                             <li class="none">Because the buffer solution wouldn’t change too much in the
 
                                                 environment, we used the buffer solution to calibrate the pH meter to
 
                                                 environment, we used the buffer solution to calibrate the pH meter to
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                                                 ensure that the deviation would the same every time.</li></br>
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                                                 ensure that the deviation would be the same every time.</li></br>
 
                                         </ul>
 
                                         </ul>
  
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                                         <ol type="a">
 
                                         <ol type="a">
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                                             <li>Insert pH meter into pH 7 buffer solution, wait about 1 min, it
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                                             <li>Insert pH meter into buffer solution of pH 7, wait for 1 min, it
 
                                                 will achieve a stable
 
                                                 will achieve a stable
 
                                                 value.</li></br>
 
                                                 value.</li></br>
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                                             </br>
 
                                             </br>
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                                             <li>Write the offset value into code, upload the code into Arduino
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                                             <li>Write the offset value into code, and then upload the code into Arduino
 
                                                 again.</li>
 
                                                 again.</li>
  
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                                             </br>
 
                                             </br>
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                                             <li>After rinsing the pH meter, insert it into pH 4 buffer
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                                             <li>After rinsing the pH meter, we will insert it into pH 4 buffer
 
                                                 solution.</li></br>
 
                                                 solution.</li></br>
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                                             <li>If it is found to be too different from the error of pH=4, you
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                                             <li>If it is found to be too different from the error of pH 4, you
 
                                                 should adjust the knob.
 
                                                 should adjust the knob.
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                                                 After inserting pH = 4, it is found that the error with 4 is very
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                                                 After inserting pH 4, it is found that the error with pH 4 is very
 
                                                 large.</li>
 
                                                 large.</li>
  
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                                         <li>Purpose</li></br>
 
                                         <li>Purpose</li></br>
 
                                         <ul>
 
                                         <ul>
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                                             <li>We assume that pH 4 to 7 is linear, so we want to verify
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                                             <li class="none">We assume that pH 4 to 7 is linear, so we want to verify
 
                                                 whether it is linear between pH
 
                                                 whether it is linear between pH
 
                                                 4 to 7. By measuring the solution of pH 4.7, compare its
 
                                                 4 to 7. By measuring the solution of pH 4.7, compare its
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                                         <ul>
 
                                         <ul>
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                                             <li>Mixing a solution with pH=4.7 and measure with a calibrated pH
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                                             <li class="none">Mix a solution with pH=4.7 and measure with a calibrated pH
 
                                                 meter.</li></br>
 
                                                 meter.</li></br>
 
                                         </ul>
 
                                         </ul>
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                                         <ul>
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                                             <li>After inserting the solution with pH=4.7, we found that the
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                                             <li class="none">After inserting the solution with pH=4.7, we found that the
 
                                                 value was stable at pH 4.83
 
                                                 value was stable at pH 4.83
 
                                                 with an error of about 0.13, which roughly met the error of
 
                                                 with an error of about 0.13, which roughly met the error of
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                 if ($(this).scrollTop() >= 90) {
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                     var position = $("#sidelist").position();
 
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                     if (position == undefined) {} else {
 
                     if (position == undefined) {} else {

Latest revision as of 21:30, 17 October 2018

pH Meter

About this section, we are showing how to use the pH meter in arduino.

Motivation


Because E. coli is sensitive to pH value, and according to the experiment of the pH sensor by WET members. We know that E. coli can’t grow below pH value of 6, and generally grow the best at pH 7.



Experiments


  • Experiment 1: Instrument calibration

    1. Purpose

      • Because the buffer solution wouldn’t change too much in the environment, we used the buffer solution to calibrate the pH meter to ensure that the deviation would be the same every time.

    2. Method

      1. Insert pH meter into buffer solution of pH 7, wait for 1 min, it will achieve a stable value.

      2. Minus the value with pH 7, and it will get the offset value. For instance, 7-7.09=-0.09.

      3. Write the offset value into code, and then upload the code into Arduino again.

      4. After rinsing the pH meter, we will insert it into pH 4 buffer solution.

      5. If it is found to be too different from the error of pH 4, you should adjust the knob. After inserting pH 4, it is found that the error with pH 4 is very large.

      6. Adjust the knob. (Remark: Because the change of the knob is small, it may have to turn a few more times until display pH 4.)

      7. Finally, it can be found that the measured pH is 4.


  • Formula calculation

    1. voltage = analog value*5/1024

    2. pH value = 3.5*voltage+offset

  • Experiment 2: Precision measurement

    1. Purpose

      • We assume that pH 4 to 7 is linear, so we want to verify whether it is linear between pH 4 to 7. By measuring the solution of pH 4.7, compare its deviation.

    2. Method

      • Mix a solution with pH=4.7 and measure with a calibrated pH meter.

    3. Result

      • After inserting the solution with pH=4.7, we found that the value was stable at pH 4.83 with an error of about 0.13, which roughly met the error of this pH meter ± 0.1 pH.


    4. Materials used

      1. Arduino UNO

      2. pH sensor
        1. Module Power : 5.00V
        2. Measuring Range:0-14pH
        3. Measuring Temperature :0-60 ℃
        4. Accuracy : ± 0.1pH (25 ℃)

      3. pH buffer solution

      4. Arduino code

Wiring


Reference


  1. Boywhy Chen.(2016).[Arduino] PH meter. Retrieved from
    http://boywhy.blogspot.com/2016/07/arduino-ph-meter.html(Augest 28,2018)




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