From: Jim Thompson
Subject: Re: Temperature Measurement Stability - +/-3.5 microdegrees
References: <3DD2EC20.2FB10158@maine.rr.com> <email@example.com> <3DD4487C.77549C50@maine.rr.com> <3DD65C67.8C2CE98C@maine.rr.com>
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Date: Sun, 17 Nov 2002 03:47:05 GMT
NNTP-Posting-Date: Sat, 16 Nov 2002 22:47:05 EST
Organization: Cox Communications
On Sun, 17 Nov 2002 03:40:28 GMT,
"Walter Driedger" ,
In Newsgroup: sci.electronics.design,
Entitled: "Re: Temperature Measurement Stability - +/-3.5
Wrote the following:
|37 C is an average, typical human body temperature. Firstly it is an
|average; actual temperatures may vary. Secondly it is typical. Daytime,
|nightime, time of the month, oral, rectal, arm pit; change is the only
|constant. Finally, it is the human average. As such it does not apply to
|dogs, gerbils, parakeets or iguanas.
|It is not some universal constant like the speed of light or even the triple
|point of water. The is no more point in measuring human body temperature to
|an accuracy greater than .1 degree than there is in declaring the
|temperature of the weather in a given city, at a given time to be 37.01. It
|varies more than 2 degrees from one side of the street to the other.
I think what the OP *really* needs is stability/repeatability; *not*
|"Raymond E. Rogers" wrote in message
|> Francis wrote:
|> > I have to ask, what on earth requires that level of accuracy.
|> > I am an engineer, not a scientist.
|> > Francis
|> I don't know if the question was directed at me but....
|> Consider medical testing, the chemical processes are tuned to 37degC.
|> In actual measurements the sensitivity of diagnostic reaction rate to
|> temperature is 1%/.15degC . We are attempting to bring to in office
|> diagnostics a series of general health tests for veterinary clinics at
|> the price range of $3.00 per test with an accuracy of around 4%. I am
|> trying to move the electronics control system completely out of the way
|> of the measurement; believe me there are a lot of other items that
|> contribute to the measurement uncertainty. I want to be able to say
|> with certainty that the temperature is stable. In fact there is a case
|> of cascading specs here: 4:1 for the chemistry and then 5:1 for the
|> electronic instruments, but I really think (in this day and age) that
|> the electronics should not be the limiting factor.
|> In the end I hope to see the technology move from the veterinary office
|> to the doctor's office and help bring down the cost of medicine. It
|> will probably happen by 2020, the question is who is going to do it.
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| Jim-T@analog_innovations.com Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
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