Re: [DIYbio] Building an incubator, would like some opinions/help

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?

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