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

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                                                 instance, 7-7.09=-0.09.</li>
 
                                                 instance, 7-7.09=-0.09.</li>
  
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                                                 <img class="oneimg" src="https://static.igem.org/mediawiki/2018/c/c1/T--NCKU_Tainan--home_03-ph_meter-2.jpg">
 
                                                 <img class="oneimg" src="https://static.igem.org/mediawiki/2018/c/c1/T--NCKU_Tainan--home_03-ph_meter-2.jpg">
 
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                                                 again.</li>
 
                                                 again.</li>
  
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                                            </div>
  
 
                                             <li>After rinsing the pH meter, insert it into pH 4 buffer
 
                                             <li>After rinsing the pH meter, insert it into pH 4 buffer
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                                                 large.</li>
 
                                                 large.</li>
  
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                                             <div class="carousel-item active pic3" style="background-image: url('https://static.igem.org/mediawiki/2018/b/b9/T--NCKU_Tainan--home_05-ph_meter-4.jpg')"></div>
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                                             <li>Adjust the knob. (Remark: Because the change of the knob is small,
 
                                             <li>Adjust the knob. (Remark: Because the change of the knob is small,
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                                                 few more times until display pH 4.)</li>
 
                                                 few more times until display pH 4.)</li>
  
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                                             <li>Finally, it can be found that the measured pH is 4.</li>
 
                                             <li>Finally, it can be found that the measured pH is 4.</li>
  
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                                         </ul>
 
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                                        </div>
  
 
                                         <li>Materials used</li>
 
                                         <li>Materials used</li>
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                                 <h3>Experiments</h3></br>
 
                                 <h3>Experiments</h3></br>
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                                 <h3>Reference</h3></br>
 
                                 <h3>Reference</h3></br>
 
                                 <ol>
 
                                 <ol>
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                                     <li>Boywhy Chen.(2016).[Arduino] PH meter. Retrieved from
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                                     <li>Boywhy Chen.(2016).[Arduino] PH meter. Retrieved from</br>
 
                                         http://boywhy.blogspot.com/2016/07/arduino-ph-meter.html(Augest 28,2018)</li>
 
                                         http://boywhy.blogspot.com/2016/07/arduino-ph-meter.html(Augest 28,2018)</li>
 
                                 </ol>
 
                                 </ol>

Revision as of 12:31, 30 September 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 about pH 7.







Experiments


  • Experiment 1:Instrument calibration
    1. Experimental 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 the same every time.
    2. Experimental method
      1. Insert pH meter into pH 7 buffer solution, wait about 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, upload the code into Arduino again.
      4. After rinsing the pH meter, 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 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
      • Mixing 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

Experiments


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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