Author Topic: COVID-19 Oral Thermo Probe?  (Read 495 times)

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Offline Richard Crowley

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COVID-19 Oral Thermo Probe?
« on: April 07, 2020, 07:41:07 pm »
So if I have thermal measuring probes (just bare thermocouples) for one or more of my DMMs....
Does anyone know of a safe oral probe thermocouple (or other type RTD?) that I can just plug into a DMM?
With as much T&M gear that we have, it seems silly/redundant to get yet another test device.
 

Offline Cyberdragon

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Re: COVID-19 Oral Thermo Probe?
« Reply #1 on: April 07, 2020, 09:41:33 pm »
Um, you can get a basic pen type oral thermometer for a few bucks in any store pharmacy section. This seems like a solution looking for a problem.
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Online sleemanj

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Re: COVID-19 Oral Thermo Probe?
« Reply #2 on: April 07, 2020, 10:35:37 pm »
DMM and K-Type accuracy and precision isn't great for temperature measurements of the human body, where 1 degree is the difference between "pretty normal" and "concerning".

With that said for a quick check, eh, just stick the usual K-Type wire probe under your tongue, wipe it down with alcohol+water if you're worried.  That's how I check my meter's temperature mode is producing plausible numbers.
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Offline Electro Detective

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Re: COVID-19 Oral Thermo Probe?
« Reply #3 on: April 07, 2020, 10:41:20 pm »

fwiw if I had to do it on the cheap, usually my first and only option  :D 

a layer or two of kitchen cling wrap on any generic thermocouple should in theory work ok 

In fact I can't see why not.  :-//

It's food grade stuff afaik, easy to fit and bin when done,
IPA on the probe to be sure and repeat


 
 

Offline jpanhalt

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Re: COVID-19 Oral Thermo Probe?
« Reply #4 on: April 07, 2020, 10:44:06 pm »
Rectal probes are more accurate for determining core temperature.

And just how will you use the result?
 

Offline Kleinstein

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Re: COVID-19 Oral Thermo Probe?
« Reply #5 on: April 08, 2020, 08:09:36 am »
Um, you can get a basic pen type oral thermometer for a few bucks in any store pharmacy section. This seems like a solution looking for a problem.
I have not heard much about these, but not sure they are still available at there normal price.

Usually they were pretty cheap and also accurate (e.g. +-0.2 K), so much that these medical thermometers are an option to check ones own thermometers.

The normal TCs may not be accurate enough. They may still show a trend.
It at all the TC should be isolated, as liquid can cause errors (e.g. electrochemical voltages).

Today the normal point to measure is with an IR thermometer in the ear.
The temperature at the heat and body may give different information. AFAIK the main regulation for the body is from the head.
 

Offline SiliconWizard

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Re: COVID-19 Oral Thermo Probe?
« Reply #6 on: April 08, 2020, 02:36:15 pm »
As said above, I wouldn't use thermocouples for this. They are meant for much wider temperature ranges. Getting +/-0.1°C is next to impossible. At least not without fancy signal conditioning and heavy calibration.

Another thought, they would probably require proper encapsulation for this application.

Medical thermometers are cheap these days and AFAIK, there is no shortage as of yet? Why bother?

But yeah, the most common approach these days seems to be IR thermometers, so if you want to design one, that's probably what you should look into.
 

Offline jpanhalt

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Re: COVID-19 Oral Thermo Probe?
« Reply #7 on: April 08, 2020, 11:01:40 pm »
As I said before, are you interested in "core" body temperature or some surrogate of that?

Whether it is forehead, ear canal, throat, all of those are surrogates and are affected  by environment in their own ways.   The IR ear method has become popular not because of its  accuracy, but because of the ease of measurement and the plethora of instruments to do it.

Why during surgery is the thermometer not attached to your ear?
 

Offline ogden

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Re: COVID-19 Oral Thermo Probe?
« Reply #8 on: April 08, 2020, 11:09:30 pm »
Does anyone know of a safe oral probe thermocouple (or other type RTD?) that I can just plug into a DMM?
There is no such thing as oral probe for DMM. Anyway most common thermocouple probes will miss required accuracy required for human body temperature measurements. As it is already suggested - just buy digital thermometer and consider your problem solved.
 

Offline blacksheeplogic

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Re: COVID-19 Oral Thermo Probe?
« Reply #9 on: April 09, 2020, 03:53:12 am »
As said above, I wouldn't use thermocouples for this. They are meant for much wider temperature ranges. Getting +/-0.1°C is next to impossible. At least not without fancy signal conditioning and heavy calibration.

I use a $5 thermometer for checking my family's temperature, I have an in-ear unit but I can never find the tip protectors.

I also have a Reference Thermapen (~US$200) that is 0.05°C, not sure of it's full range where it meets that full spec but it meets 0.1°C from -70°C  thu to 200°C. For the precision, it's probably on the the lower end cost wise. Would not use it for taking my daughters tempature.
 

Offline mzzj

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Re: COVID-19 Oral Thermo Probe?
« Reply #10 on: April 09, 2020, 03:56:43 am »
As said above, I wouldn't use thermocouples for this. They are meant for much wider temperature ranges. Getting +/-0.1°C is next to impossible. At least not without fancy signal conditioning and heavy calibration.

Another thought, they would probably require proper encapsulation for this application.

Medical thermometers are cheap these days and AFAIK, there is no shortage as of yet? Why bother?

But yeah, the most common approach these days seems to be IR thermometers, so if you want to design one, that's probably what you should look into.
Good cold junction temperature measurement and 1-point calibration should get T-type thermocouple to within +-0,1°C in the interesting range.
Problem is that none of the dmm's have "good" cold junction compensation so you would need to build your own around thermistor or Pt1000. And at that point you can just stick that Pt1000 in your mouth as well  ;D
 


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