[Bio] Post-meeting thoughts and NIR probe

Otute Akiti oakiti at gmail.com
Wed Apr 6 12:21:34 PDT 2011


A standard pH probe contains both the reference electrode and the pH sensing
electrode in the same housing, and therefore has two wires.
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.

-Otute

On Tue, Apr 5, 2011 at 11:33 PM, Rolf <rolfvw at gmail.com> wrote:

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