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Author Topic: [NEWBIE] Best thermopile for use in ear thermometer  (Read 628 times)
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Hi Guys,

Please be patient, I'm a complete newbie to hardware.

I'm trying to find the best thermopile to use for an in-ear thermometer to continuously measure core body temperature, see: http://arduino.cc/forum/index.php/topic,105922.0.html

My criteria are:
- compact enough to fit inside an ear-bud housing
- sensitive to at least 0.05 C
- relatively easy to read from using arduino

Here are the thermopiles I'm looking at so far:

Melexis' MLX90614ESF-BAA
http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=MLX90614ESF-BAA

Melexis' MLX90614ESF-DCI
http://search.digikey.com/scripts/DkSearch/dksus.dll?WT.z_header=search_go&lang=en&site=us&keywords=MLX90614ESF-DCI-ND&x=0&y=0

Can somebody explain to me why I'd want to buy the DCI over the BAA? It's quite a bit more expensive.

TPS333 http://www.alliedelec.com/search/productdetail.aspx?SKU=70219621 , TPiD 012B or TPiD 022B http://www.excelitas.com/Downloads/TPiD%20012B%20TPiD%20022B%20Thermopile.pdf.

Your feedback is very much appreciated.

Thanks,

bodhibyte
« Last Edit: May 16, 2012, 01:26:54 am by bodhibyte » Logged

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I fear in-ear thermometer experts are rather thin on the ground here...  You might have to take on that role yourself(!)
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Quote
Can somebody explain to me why I'd want to buy the DCI over the BAA? It's quite a bit more expensive.

Take a look at the datasheet. Two factors are relevant: the sensor's viewing angle (although in your case this might be no concern) and the accuracy (page 30-31). The DCI has an accuracy of 0.1°C within the temperature windows of a human body (35-40°C) where the BAA has 0.5°C. You have to decide if your experiment allows for +/- 0.5°C values or if you need more precision. The resolution of both sensors is identical, so if you just need differential values, you're fine with the BAA. If you're interested in the absolute values you should go with the DCI.
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Quote
Can somebody explain to me why I'd want to buy the DCI over the BAA? It's quite a bit more expensive.

Take a look at the datasheet. Two factors are relevant: the sensor's viewing angle (although in your case this might be no concern) and the accuracy (page 30-31). The DCI has an accuracy of 0.1°C within the temperature windows of a human body (35-40°C) where the BAA has 0.5°C. You have to decide if your experiment allows for +/- 0.5°C values or if you need more precision. The resolution of both sensors is identical, so if you just need differential values, you're fine with the BAA. If you're interested in the absolute values you should go with the DCI.

Wow, that's great. I didn't notice the longer datasheet until now. Thanks for explaining and pointing that out.
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