A standard pH probe contains both the reference electrode and the pH sensing electrode in the same housing, and therefore has two wires.<div>For our implementation I am thinking of building two separate electrodes one for reference and the other for the pH measurement - each with its own wire and therefore 2 wires for the whole setup. That should serve us fine.</div>
<div><br></div><div>-Otute</div><br><div class="gmail_quote">On Tue, Apr 5, 2011 at 11:33 PM, Rolf <span dir="ltr"><<a href="mailto:rolfvw@gmail.com">rolfvw@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Otute, great to hear you contacted him! (and that he responded... cool)<br>
<br>
Although my knowledge of chemistry and how these probes work is very limited,<br>
it does kind of make sense that his method uses the same mechanism for<br>
generating voltage. Besides, you had told me the same thing!<br>
<br>
I will continue on the probe amplifier design as if it was a normal<br>
glass membrane<br>
probe. There will be adjustments for fine tuning and calibration.<br>
<br>
I hope you can solve the mystery of the 2nd wire.<br>
Electricity needs two wires :-)<br>
<br>
By the way, how does a standard glass membrane probe create two wires?<br>
<font color="#888888"><br>
-rolf<br>
</font><div><div></div><div class="h5"><br>
On Tue, Apr 5, 2011 at 11:08 PM, Otute Akiti <<a href="mailto:oakiti@gmail.com">oakiti@gmail.com</a>> wrote:<br>
> Hello All,<br>
><br>
> To follow up with the pH probe, I contacted Prof Goldcamp to inquire about<br>
> the probe they published the paper on.<br>
> He said they were able to use the probe with a standard pH meter without<br>
> modification - which leads me to conclude that the signal output from the<br>
> probe leads must be just as in a commercial probe. This remains to be seen.<br>
> The materials are on order and I should have a prototype hopefully by next<br>
> week. What wasn't mentioned in the paper clearly is that a second reference<br>
> electrode is needed for the whole setup to work. They used a commercial one<br>
> - odd. I will try to build the reference electrode just like the main one<br>
> only with a different solution. That should work :)<br>
><br>
> Cheers,<br>
><br>
> -O.<br>
><br>
><br>
> On Tue, Apr 5, 2011 at 5:18 PM, Rolf <<a href="mailto:rolfvw@gmail.com">rolfvw@gmail.com</a>> wrote:<br>
>><br>
>> Hi Folks!<br>
>> It was good to see everyone yesterday, and get updated on what people<br>
>> are working on.<br>
>> Too bad it got so noisy at Noiseybridge!<br>
>><br>
>> I went ahead and ordered some parts today (will expense with Rikke<br>
>> soon) for the<br>
>> pH amplifier. It's going to be quite an effort.<br>
>> I also will get some phototransistors for the NIR probe.<br>
>><br>
>> I found some parts that are well matched for the 850nm IR LEDs that I<br>
>> brought in<br>
>> yesterday. It's the Optek OP506B. They cost 80 cents each.<br>
>> A very simple circuit is required around it, and it might even work<br>
>> with a couple<br>
>> resistors.<br>
>> I think the probe will require 3 wires: +5v power, signal output, and<br>
>> GND (hopefully shielded).<br>
>><br>
>> If these parts work, then the mechanicals should be straightforward.<br>
>> The LED and the detector are both 3mm LED-like packages.<br>
>> This should make it easier to design a probe around it.<br>
>><br>
>> Cheers,<br>
>> -rolf<br>
>><br>
>><br>
>> On Sun, Apr 3, 2011 at 1:37 AM, Rikke Rasmussen<br>
>> <<a href="mailto:rikke.c.rasmussen@gmail.com">rikke.c.rasmussen@gmail.com</a>> wrote:<br>
>> > Hey all,<br>
>> > Welcome to the Biobridge mailing list! By way of introduction, here's a<br>
>> > quick update on present status and future plans for the BioBridge group.<br>
>> > Our current project, the BioBoard, one of the entries in the Great<br>
>> > Global<br>
>> > Hackerspace Challenge, is coming along really nicely. For any<br>
>> > subscribers<br>
>> > unfamiliar with the project, we're basically building a bunch of<br>
>> > different<br>
>> > sensors (temp., pH, dissolved oxygen, NIR spectrometer), hooking them up<br>
>> > to<br>
>> > a microcontroller and transmitting the sensor data to a server somewhere<br>
>> > with a web app that plots a nice graph for you so you can monitor your<br>
>> > microbial culture in real time from the comfort of your couch.<br>
>> > What we've got so far:<br>
>> > Sensors<br>
>> > - thermometer: 2 different set-ups (one-wire digital thermometer,<br>
>> > thermistor), both functional (yay!) - Charlie's the man here<br>
>> > - pH: several leads, and at least two good brains chippin' away at the<br>
>> > problem - Rolf and Otute are the dudes on the job<br>
>> > - dO: solvent sandwiched in a cheap and beautiful mylar/vinyl bilayer,<br>
>> > catalyst to arrive on Thursday - Sean's got it down<br>
>> > - NIR: have a fairly decent plan for the LED/photosensor part, but need<br>
>> > help<br>
>> > regarding circuitry and wiring - Rikke's fumbling with this one<br>
>> > Microcontroller<br>
>> > - Arduino board + ethernet shield have been successfully delivered to<br>
>> > Marc<br>
>> > (I hope?)<br>
>> > - alternative suggestions have come up, we'll go through the pros and<br>
>> > cons<br>
>> > of each on Monday<br>
>> > Software<br>
>> > - we've been given an Arduino sketch for above assembly<br>
>> > Project group meetings are on Mondays at 7:30pm at Noisebridge, (new)<br>
>> > deadline is March 3rd. Current plan is another 2 weeks of sensor<br>
>> > building,<br>
>> > then a week of assembling and testing and a final week of fine tuning<br>
>> > the<br>
>> > final product. All of this ends in a big finale at Maker Faire (where<br>
>> > Biobridge will hopefully also be represented at the Noisebridge table at<br>
>> > least some of the time), May 21st-22nd.<br>
>> > Once Maker Faire is over, it is my hope that we can start hosting<br>
>> > regular<br>
>> > classes at Noisebridge - both theoretical (intro to general<br>
>> > microbiology,<br>
>> > specific aspects of bacteriology/mycology/phycology as relevant,<br>
>> > biochemistry/molecular biology/genetics, ecology & evolution) and<br>
>> > practical<br>
>> > (aerobic/anaerobic fermentation, bacterial/algal cultivation, mushroom<br>
>> > growing, selection/mutagenesis/mating group experiments, basic<br>
>> > transformation, whatever else we think of or find someone to teach)<br>
>> > ...in<br>
>> > short, all the fun we can have with microbes. We might well use the<br>
>> > wiki to<br>
>> > plan this - all input is valued!<br>
>> > Thoughts, ideas, comments?<br>
>> > /Rikke<br>
>> > _______________________________________________<br>
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>> ><br>
>> ><br>
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</div></div></blockquote></div><br>