Building an incubator, would like some opinions/help

[Nathan McCorkle]

So I am thinking of using a glass jar with sterile water and a sonic fogger to add RH.

Adding heat and stirring the air will be accomplished by a 12V 12A hair dryer. I think this MOSFET will work (the volts and amps are above what I need, but the power dissipation isn't) can someone confirm this will work or not?

http://www.onsemi.com/PowerSolutions/product.do?id=NTD5867NL

I am thinking two dampers (one-way air valves) with a small 100mm computer fan will be sufficient for reducing CO2 levels.

Because the fogger requires a specific water level for best performance, to reduce contamination I found this optical fluid level sensor setup... it just uses two LEDs and two photosensors.

http://moab.eecs.wsu.edu/~pedrow/classes/ee415/Fall_2005/Refereed%20Papers/paper1_garnet.pdf

So thoughts? opinions?

Thanks!

--
-Nathan

[ByoWired]

On Friday, January 4, 2013 3:20:24 AM UTC-5, Nathan McCorkle wrote:

So I am thinking of using a glass jar with sterile water and a sonic fogger to add RH.

Adding heat and stirring the air will be accomplished by a 12V 12A hair dryer...

Nathan,

are you sure that's 12 amps at 12 volts?  That would be only 144 watts.  That seems somewhat wimpy for a hair dryer.  Are you sure that's not 120 volts?   Most hair dryers use about 750 watts to 1500 watts.  For an incubator, why not use some power resistors and a fan?   

[Mega]

That actually would mean 1.5 kilowatts . That's a lot. That would easily burn the bugs. Our central heating unit has some 15 kW, but it heats the whole house, and a room-heat-radiator usually has some 1 kW.

It depends, of course, on how big the incubator is and how well-insulated. But actually, if good insulated, *some* watts will be enough, although pre-heating will be needed. I assume 144 Watts to be enough (if not much too much) anyways.
To heat one cubic meter air 15°C (Room temperature -> 35°C) you need (cp*mass*dT=1,005*1,2*15) 18 Joule which equals 18 Watt-seconds. That means, if it had 18 Watt it could heat 1m^3 per second. And as the incubator is insulated, you don't need to heat one cube meter per second, just compensate for the loss.



What you ment was also my approach, with the styrofoam incubator, some power resistors (and maybe a yet to be installed fan from a deceased computer). It's standing in my garage still...

[John Griessen]

On 01/04/2013 02:20 AM, Nathan McCorkle wrote:
> So I am thinking of using a glass jar with sterile water and a sonic fogger to add RH.
>

> Adding heat and stirring the air will be accomplished by a 120V 12A hair dryer. I think this MOSFET will work (the volts and amps

> are above what I need, but the power dissipation isn't)

You can give that FET short PWM pulses and keep the average power in its range, or
it will burn up.

Hair dryer fans seem fast and noisy for this app.

If you use a wimpy quiet computer fan and separately PWM control the hair dryer heater,
to slowly swirl air through the hair dryer and incubator, you could recycle the
heated air and it all would be stable.

Hair dryers are not intended to recycle their heated air, and will overtemp shutdown
if you do.

Better be swirling the 120VAC hair dryer air around the jar
and not the humid misted air water through the hair dryer...

> I am thinking two dampers (one-way air valves) with a small 100mm computer fan will be sufficient for reducing CO2 levels.

Don't have a picture of that... relative to the jar == ?

[Patrik D'haeseleer]

I assume he actually did mean 12V/12A. There's a number of "travel" hair dryers on the market that plug into the cig lighter socket in your car. Often labeled "Hair Dryer/ Defroster":

http://www.amazon.com/RoadPro-RPSC-818-Defroster-Folding-Handle/dp/B000BHQ5JC

I bet they suck if you actually try to use them as a hair dryer, but they should be perfect for an incubator, where a 1.5kW heater would be overkill. It's a good solution for a tiny heater + fan, and keeping line voltage out of the incubator is probably a good idea too.

Patrik

[Nathan McCorkle]

Ahh, I DID mean 12V not 120V! TYPO! Yeah it's a 'hair dryer' but it's sold for car use, like defrosting ice in the cold morning when the engine isn't warm to blow heat.

I was planning on PWMing the MOSFET on the dryer, I doubt it will overtemp shutdown (the one I bought seems so cheap they probably didn't add that feature) because I'm only keeping the incubator at max 40 C degrees, and it's such a small volume that I the temps will stabilize within a few seconds. 

I also was thinking that my temp ramp rate needs to be slower than my temp+RH sensor can update (by PWM and maybe undervolting the heater), so if I need to add PID control, it would be less likely to overshoot and get into some weird oscillation.

I WAS planning on having the 12V heater and 12V fan IN the incubator, I was just hoping that the fan wouldn't short. I supposed I could add a bit of magnet to a fan blade for an encoder and make sure I see ticks when I turn on the fan.

I should also mention I ordered an opto-isolated 4-relay circuit board to switch the 12V and 120V (the fogger). I also considered using a $25 marine bilge pump fan for swirling the air inside, but I think a quick coating of compressed/canned polyurethane spray would seal a simple fan enough... I would hope the coils in the motor were all insulated anyway (or they wouldn't work as coils I think)

Here's a diagram

http://nathanmccorkle.com/DIY/DIYincubator.png

--
-- You received this message because you are subscribed to the Google Groups DIYbio group. To post to this group, send email to diy...@googlegroups.com. To unsubscribe from this group, send email to diybio+unsubscribe@googlegroups.com. For more options, visit this group at https://groups.google.com/d/forum/diybio?hl=en
Learn more at www.diybio.org
--- You received this message because you are subscribed to the Google Groups "DIYbio" group.
To post to this group, send email to diy...@googlegroups.com.
To unsubscribe from this group, send email to diybio+unsubscribe@googlegroups.com.
Visit this group at http://groups.google.com/group/diybio?hl=en.

For more options, visit https://groups.google.com/groups/opt_out.

--
-Nathan

[Josiah Zayner]

Most non-shaking dry incubators don't even have fans. If you are using it for plates I would in fact advise against fans or major airflow as these tend to dry out the plates in my experience. A temperature controlled incubator can be created with one or two $3.50 thermoelectric peltier devices, TEC127601 is probably good, a temperature sensor, a microcontroller and some kind of insulated box.

Good luck.

--
-- You received this message because you are subscribed to the Google Groups DIYbio group. To post to this group, send email to diy...@googlegroups.com. To unsubscribe from this group, send email to diybio+un...@googlegroups.com. For more options, visit this group at https://groups.google.com/d/forum/diybio?hl=en

Learn more at www.diybio.org
--- You received this message because you are subscribed to the Google Groups "DIYbio" group.
To post to this group, send email to diy...@googlegroups.com.

To unsubscribe from this group, send email to diybio+un...@googlegroups.com.

Visit this group at http://groups.google.com/group/diybio?hl=en.

For more options, visit https://groups.google.com/groups/opt_out.

--
-Nathan

[Nathan McCorkle]

On Fri, Jan 4, 2013 at 12:39 PM, Josiah Zayner <josiah...@gmail.com> wrote:

Most non-shaking dry incubators don't even have fans. If you are using it for plates I would in fact advise against fans or major airflow as these tend to dry out the plates in my experience.

They won't dry out because I am electronically controlling the RH 

[John Griessen]

On 01/04/2013 02:22 PM, Nathan McCorkle wrote:
> I WAS planning on having the 12V heater and 12V fan IN the incubator,

OK. 12V in the humid/mist will die with a whimper instead of a fire.
Is the "window dryer" cheap to replace? How humid? Sonic fog
can be like a mist of rain...
Sounds like tough duty for it... but should go for a while. Tell us how long.


again:

[Nathan McCorkle]

On Fri, Jan 4, 2013 at 1:17 PM, John Griessen <jo...@industromatic.com> wrote:

On 01/04/2013 02:22 PM, Nathan McCorkle wrote:

I WAS planning on having the 12V heater and 12V fan IN the incubator,

OK. 12V in the humid/mist will die with a whimper instead of a fire.
Is the "window dryer" cheap to replace?  How humid?  Sonic fog
can be like a mist of rain...
Sounds like tough duty for it...  but should go for a while.  Tell us how long.

The dryer was <$13 on amazon.com with free shipping. I'm planning on having the humidity around 95%, and the temp around 30 C, it looks like I'll be playing right around the dew point. I was also thinking of a mechanically coupled fan, but didn't find something like that in my searching on amazon.com

 

again:

 >   I am thinking two dampers (one-way air valves) with a small 100mm computer fan will be sufficient for reducing CO2 levels.


Don't have a picture of that...  relative to the jar == ?

 here ya go

http://nathanmccorkle.com/DIY/DIYincubator.png

one fan provides positive pressure for the incubator, the other fan is in the incubator and is just there to swirl the air (relative to the jar, it's just near it)

-- 

-Nathan

[Jonathan Street]

Hi Nathan

I'm not sure we have enough information to provide useful suggestions but at first glance this seems over-engineered.

How large do you intend building this incubator? What do you plan to grow in it?

Have you had problems using a pan of water in the bottom of an incubator in the past?

Is the metabolic rate and/or loading of this incubator going to be so high that the CO2 level could not be adequately maintained by a small hole in the top of the incubator?

--
-- You received this message because you are subscribed to the Google Groups DIYbio group. To post to this group, send email to diy...@googlegroups.com. To unsubscribe from this group, send email to diybio+un...@googlegroups.com. For more options, visit this group at https://groups.google.com/d/forum/diybio?hl=en

Learn more at www.diybio.org
---
You received this message because you are subscribed to the Google Groups "DIYbio" group.
To post to this group, send email to diy...@googlegroups.com.

To unsubscribe from this group, send email to diybio+un...@googlegroups.com.

[Nathan McCorkle]

My thoughts are that the control system and sensors would be able to
easily scale to any sized incubator. From what I've read the best
incubators have fans in them to keep CO2 levels even, since it tends
to settle in a taller incubator, and this gradient can cause
inconsistencies in growth.

For this system, including temp, RH, and CO2 sensors, as well as the
small heater, fogger, and CO2 gas valve, microcontroller, power
supply, and assorted electonics.... I'm at a cost of ~$175, with the
CO2 sensor being the most expensive piece at $65 (but its got a 15
year life and doesn't need recalibration so it's an easy justification
for me not to deal with the electrolytic ones)

But of that $175, ~$45 is going towards the heater+power supply and
the fogger. These items are the only ones you'd really change around
with incubator scale, so you could use this system to control a small
1ft x 1ft incubator or a 10ft x 25 ft greenhouse.

FYI:
temp+RH sensor
$15 + ~$3 shipping
http://www.adafruit.com/products/393

CO2 sensor
$65 + ? shipping
http://www.co2meter.com/collections/co2-sensors/products/k-30-co2-sensor-module

Ultrasonic Mist Maker Fogger Water Fountain Pond 12 LED
$13
amazon.com

5V 4x opto-isolated relays
$8.87
http://www.amazon.com/SainSmart-4-Channel-Relay-Module-Arduino/dp/B0057OC5O8/

12V 12A heater
$11.73
http://www.amazon.com/Roadpro-12V-Heater-Swing-out-Handle/dp/B000IXTGHW/

12V gas valve
$14
http://www.amazon.com/Electric-Solenoid-Replacement-Pipelines-Applications/dp/B00827FP26/

12V 15A power supply
$17
http://www.amazon.com/Regulated-Switching-Power-Supply-Silver/dp/B007MJJX46/

5V power supply, arduino clone, LEDs+photodiodes, PC fan, power MOSFET
$35

plastic tub for actual climate controlled area, glass jar for RH water reservoir
$6

--
-Nathan

[John Griessen]

On 01/04/2013 07:04 PM, Nathan McCorkle wrote:
> CO2 sensor
> $65 + ? shipping

That's a lot to spend. Some kind of CO2 estimate for the conditions
in a humid incubator with no weird gases coming off the contents
must be possible for less money. Why not make a crude one from
scratch that your microcontroller can read?

Hmmm... CO2 direct measurement is not so easy...like when I worked
at SBRC with dual band sensors... maybe $65 is not so far off..

Here's the main claim of "ultra low cost sensor" patent 20070029487 of 02/08/2007:

"A single beam NDIR gas sensor for detecting the concentration of a gas species, comprising: a thermally insulated tube sample
chamber; an incandescent miniature light bulb with a filament surrounded by a glass envelope secured at a first end of the sample
chamber; a single infrared detector secured at a second end of the sample chamber; a dual bandpass filter mounted at the single
infrared detector between the bulb and the detector, said dual bandpass filter having a neutral passband and an absorption
passband for the gas species; a controlled heater secured to the tube for maintaining the sample chamber at a preselected
temperature greater than an ambient temperature when the sensor is turned on; a driver for the bulb with a high input power level
and a low input power level so as to render said bulb into emitting at a first voltage output and a second voltage output whose
radiation outputs are characterized by two corresponding Planck curves dependent upon temperatures; a feed back loop to sense an
operation voltage of the bulb; "

It's a dual wavelength discriminator...a complex optical assembly in other words...

So, how about an O2 sensor instead? Could you do that?

[Nathan McCorkle]

On Fri, Jan 4, 2013 at 7:07 PM, John Griessen <jo...@industromatic.com> wrote:
> It's a dual wavelength discriminator...a complex optical assembly in other
> words...
>
> So, how about an O2 sensor instead? Could you do that?
>

the only O2 sensors I know of are in my automobiles' tailpipes, and
they need high temp to get working. Car's have a 3-wire version that
includes its own heater circuit, look's like they're around $40 and
need 600 F + temps (the 1-wire non-self-heating are $16 but still need
to get hot somehow)

actually i just found this for $184
http://www.grainger.com/Grainger/MSA-Replacement-Sensor-2TEX8?BaseItem=2TEY8

The bioBoard project at noisebridge tried their hand at making a
dissolved oxygen probe (optode), that the oxygen sensor wikipedia
article leads me to believe would also work for air
https://www.noisebridge.net/wiki/BioBoard#Dissolved_oxygen_.28DO.29_probes

wikipedia also mentions galvanic oxygen sensors
http://en.wikipedia.org/wiki/Oxygen_sensor#Scientific_applications


BUT, I think an O2 sensor could be complementary to a CO2...
substituting would depend on the case as well as price

Here's a quick CO2 blurb
http://wiki.answers.com/Q/What_is_the_role_of_carbon_dioxide_in_mammalian_cell_culture

Then there's Nitrogen too...

hydrogen looks cheap and easy at $7.95 (the L.A. biohackers were
trying to grow some extremophile in hydrogen I think)
https://www.sparkfun.com/products/10916

ahh but it looks like it isn't temperature compensated, though it
includes a heater on-sensor
http://wiki.biohackers.la/Nitrogenase_Directed_Evolution#Bioreactor_Setup

that's the same problem with the $19 CO2 electrolytic sensor they're
using (which is why i figured a 3X price increase was worth not
screwing with compensation):
http://www.futurlec.com/Gas_Sensors.shtml

--
-Nathan

[Nathan McCorkle]

plus the co2meter.com product has some code and a library for arduino,
so even easier

--
-Nathan

[Patrik D'haeseleer]

Did you see this one:

http://arduino.cc/forum/index.php/topic,91467.0.html

I couldn't find a price for this Cozir sensor, but it does temperature, humidity and co2, and supposedly only took 2 minutes to hook up to an Arduino.

Patrik

[John Griessen]

On 01/04/2013 09:44 PM, Nathan McCorkle wrote:
> actually i just found this

Thanks for all those links. It seems gas sensors are just not a simple
packaging job to get costs down. Making any one of them low cost
is going to run against patents and tough design work and lots of testing,
but if something crude could be developed, with good warnings about its
failings, and when it can be trusted, we, (open lab gear makers),
could evolve that along.


Is this module what you're trying out?
http://www.co2meter.com/products/k-30-co2-sensor-module $65.00 US

[John Griessen]

On 01/05/2013 03:01 AM, Patrik D'haeseleer wrote:
> I couldn't find a price for this Cozir sensor, but it does temperature, humidity and co2, and supposedly only took 2 minutes to
> hook up to an Arduino.

http://www.ttnet.net/ttnet/gotoprd/ET110/090/0/1383639383831343633353339313939303037363137333.htm

datasheet says it has sensirion sht21 on board for rH, T.

Making an open hardware module with the code open and able to use various chinese
zirconium CO2 sensors as promoted for home safety market would be good...and it
could be low power pretty easily. The rH, T sensors could be optional modules.
Temperature is almost always available to within 1 deg C with recent microcontrollers,
since they have voltage references and an internal die monitoring temperature derived
from diode voltage drop characteristics over temperature.

Using sensirion sht21 adds about $7 to the BOM for its convenience.

[John Griessen]

What CO2 sensitivity range is useful for incubating cultures?
Does fermentation go above 5% concentration sometimes -- seems like it could..

When incubating, do you always want to keep CO2 down to normal atmosphere levels?

Gas sensors come in ranges that can be too sensitive to monitor fermentation
in closed containers, so I'm just wondering what to ask for as I do a little
digging into what's available.

[Cory Tobin]

> hydrogen looks cheap and easy at $7.95 (the L.A. biohackers were
> trying to grow some extremophile in hydrogen I think)
> https://www.sparkfun.com/products/10916
>
> ahh but it looks like it isn't temperature compensated, though it
> includes a heater on-sensor
> http://wiki.biohackers.la/Nitrogenase_Directed_Evolution#Bioreactor_Setup

Yeah, that was me. Do yourself a favor and avoid the $10 H2 and CO2
sensors. For H2 I was using that one from sparkfun and for CO2 I was
using http://tinyurl.com/b6ckxao They are completely worthless. They
only work well at constant temperature and humidity. And each
individual sensor has to be calibrated separately. I wasted a couple
of months trying to calibrate those things at different temperatures
and humidity levels :/

I eventually gave up trying to measure H2 and CO2, but I imagine any
NDIR sensor (like the one from co2meter.com) will work much better.
They cost more but you will save a lot of time, effort, and gray
hairs.

-cory

[John Griessen]

On 01/04/2013 09:59 PM, Cory Tobin wrote:
> I eventually gave up trying to measure H2 and CO2, but I imagine any
> NDIR sensor (like the one from co2meter.com) will work much better.
> They cost more but you will save a lot of time, effort, and gray
> hairs.
>
> -cory

Thanks. I have a quote request in for a NDIR sensor, just to see.
It does't have a rH and T sensor built in, and could be generic
and inexpensive, yet it does spec running over a
big (0 to 95% RH) rH range with 2% of full scale accuracy.

[Nathan McCorkle]

John, it looks like Palladium is a better choice than Al or Sn (the
latter is in the SparkFun item)... I e-mailed these folks who are in
your town, asking for pricing. If they don't get back to me, I'll let
you know, and maybe you can drop in some time on them.


"
Metal Nanoparticle Sensors (MNPS)
We have developed a nanotechnology enabled Metal Nanoparticle Sensor
(MNPS). The first product in this platform is a palladium
nanoparticle-based hydrogen sensor. Nanoparticles of palladium provide
high surface to bulk ratio compared to macro scale palladium thin
films used for hydrogen sensing. Our nanoparticle sensor has an
increased percentage of active surface atoms that detect molecular
events more effectively and maximize sensor signal in comparison to a
thin film. The effective surface area of nanoparticles increases on
reaction with hydrogen causing electrical shorts within a random
network resulting in a change of electrical conductivity.
"
http://www.appliednanotech.net/tech/mnps.php
http://www.appliednanotech.net/tech/pdfs/071105_mnps_b_h_sensor.pdf



here's some molecular overview of other Pd H sensor technologies:
http://www.h2scan.com/pdfs/TechnologyBackground.pdf
http://mems.caltech.edu/courses/EE40_old/Gas%20Sensors%20BioSensors.pdf

Hydrogen Gas Detection System Prototype with Wireless Sensor Networks
http://www.di.ufpe.br/~redis/intranet/bibliography/middleware/nakano-gas05.pdf

[Nathan McCorkle]

On Fri, Jan 11, 2013 at 4:07 PM, Nathan McCorkle <nmz...@gmail.com> wrote:
> John, it looks like Palladium is a better choice than Al or Sn (the
> latter is in the SparkFun item)...

I meant the latter two elements (Al and Sn) being used in the SparkFun item

--
-Nathan