Wrist-Mounted Body Temperature Sensor

I think there are RTDs incorporated into small rectangles of flexible material. These might do well as far as making good contact with the skin. However, I'm not sure how well skin temp correlates with body temp, and it may depend on the insulation value of whatever wraps around the wrist. Hard to say if consistent and meaningful readings would result. Interesting project, though. What is in mind for a pulse detector?

There are several different technologies used for measuring skin temperature - RTDs, thermocouples, thermopiles, thermistors, and so forth - but thermistors (literally, "thermal resistors") are by far the most sensitive of the lot and are commonly used for measurements of skin temperature and other, similar applications.

Unlike their temperature-sensing cousins, however, thermistors are not linear. That is, a plot of a thermistor's resistance-vs-temperature curve is not a straight line, but has a characteristic S-shape to it. This is hardly a drawback, fortunately, as the R-T curve closely follows the so-called Steinhart-Hart relation, allowing you to accurately derive the temperature from the resistance value:

1/T = a + b[ln(R_T)] + c[ln(R_T)]² + d[ln(R_T)]³ , where

T = temperature, expressed in kelvins (°C + 273.15),

a, b, c, d = process- and material-specific parameters determined and supplied by the thermistor mfr.,

R_T = thermistor resistance, in ohms, at a given temperature.

One of the best thermistor mfrs, in my opinion, is Vishay. Vishay would be a good place to start, IMHO.

Hope this helps.

-e

I have a backround in Cardiac Pacemakers. I have never heard of taking a temperature of the wrist and I do not know if this is accurate temperature. Typically it is under the tongue, inside the ear, or rectum. At doctor offices they use disposable under the tongue measurement.

As far as pulse measurement at the wrist this is commercially available. And there are other ways to due it as well.

I agree with Mave Man, the wrist is NOT a good place to measure temperature accurately.

But with a yard or so of cable attached to the sensor, you can extend it up the arm to eventually reach the person's rectum and measure continuously and very accurately....

.....this may be a cause for much laughter in the Golf Club changing rooms though, so I cannot see it catching on somehow......

Which could be also the reason that nobody has "thought of it" before!!!

You might try using a "wireless" version using "Bluetooth" radio communication, the trouble there being something like " I had a bad attack of gas/runny tummy/Montezuma's revenge/etc, pooped and lost my sensor, can you supply me with a new one please?"

Seriously for a moment, Bluetooth could be used for an under arm sensor if temperature is needed constantly. As I cannot imagine someone allowing such a sensor either under the tongue, in the ear or the rectum for long periods. (For "long" read anything over 5 minutes.....)

And speaking of Bluetooth, you could 'just' build your temp sensor (a thermopile, in this case) into one of those Bluetooth headsets you wear in your ear that makes people look like Borg wannabes. Then, while you're talking to your doctor, it butts in and tells her you have a fever of 107 and that you'd better get your butt over to the ER pronto-like before you keel over.

Then it screams and [CLICK]

LOL

Sounds painful, a Thermopile!!!! OUCH!!!!

I'm tellin' ya!

a wireless rectal sensor LOL

Bluetooth under arm seems interesting, i'll suggest this to my group. Thanks!

Harinder

Hello Maveric,

yes the measurement at the wrist wont be the best, we might consider some other solution. Thanks for the heads up though.

In terms of the pulse measurement, we are considering either a sensor at the wrist or a pulse oximeter. Although with the latter, the device would no longer be strictly a "wrist" device. Are you aware of any quality pulse sensors which would work at the wrist?

Appreciate your input. Thank you.

Harinder

There are some (very cheap!) watches that sense with a wrist strap the pulse rate, so it is possible.....

Deleted as it was already mentioned.

I've used these

http://www.analog.com/static/imported-files/data_sheets/AD592.pdf

for some temperature sensing applications. Not cheap, but linear and simple to interface with. Thermistors and thermocouples should work fine also.

We use NTC thermistors from GE. The higher accuracy ones (Rs.25/- each in bulk) have a 0.1 ºC accuracy and have a fast enough response. They have other versions too.

http://gethermometricsindia.com/NTCRadialChip.htm

Body temperature (which is generally meant to be inner body temperature or core temperature) is not skin temperature. Skin temerature depends on core temperature + lots of internal and external parameters.

If body temperature has to be measured specifically at a subject's wrist, a measurement of the pulse artery temperature (not the skin temperature) may produce results that are closer to body temperature.

This could be an interesting (and perhaps innovative) project.

Hi VyRuS,

I am not sure how effective the measurement you suggest will be. Any extremety can be virtually 'frozen' yet the core of the body is still working.

However I can see it may be of use in a person who is in a regulated temperature.

Please see below. These papers describe exactly what you are talking of.

• [DOC] Abstract-Papers up to 4 pages should be submitted using this formatFile Format: Microsoft Word
  Home care, ambulatory measurements, permanent monitoring are ... Rib cage and abdominal respiration measurement, Core temperature, body heat flow), ... use those facilities with a network of embedded sensors to measure and monitor non .... Wrist device and data logger are designed to process, to record and to ...
  www.wealthy-ist.com/uploads/insa.doc - Similar -
• Temperature measurement: MedlinePlus Medical EncyclopediaYou can measure the temperature on three body locations: ... Leave the thermometer in the mouth for 3 minutes or until the device beeps. ...
  www.nlm.nih.gov/medlineplus/ency/article/003400.htm - Cached - Similar -
• Temperature Measurementwww.thermocouplesensors.co.uk Free Guide to Temperature Measurement for Engineers!
• 
  

  Sports Bra Measures Heart Rate NuMetrex has a new sports bra, the NuMetrex Heart Sensing Sports Bra, that has heart monitoring technology sewn into the fabric. The bra monitors the heart's pulse and transmits data to a wrist watch. The NuMetrex Heart Sensing Sports Bra was launched by Textronics in December 2005, and was named 2006 Sports Product of the Year by the Sporting Goods Manufacturers Association. The garment features electronic sensing technology that is actually integrated right into the knit of the fabric, which picks up the heart's electrical pulse and radios it to a wrist watch via a tiny transmitter in the bra. It offers a new level of comfort and convenience for women wishing to monitor their heart rate while they exercise. Textronics is currently working to expand the NuMetrex clothing collection to include a heart rate sensing shirt for men which will be released to market this fall. Also in development is a larger size heart rate sensing sports bras for women targeted for release in early 2007. NuMetrex uses technology from Textronics, which develops what they are calling electro-functional fabrics. There should be many more developments like this one in the years ahead. Posted on September 14, 2006 Permalink | ShareThis | Buzz up! | 0 Comments

  
  

  Wristwatch Helps With Supervision of Elderly Patients Exmocare has launched a web-based bluetooth-enabled biosensor wristwatch service. The service is aimed at helping with medical supervision of the elderly. The services includes a wristwatch that monitors its wearer's pulse, heart rate variability, skin conductance and activity level via a built in accelerometer. Exmocare says the wristwatch can also provides rudimentary assessments of up to 10 different emotional states, including when its elderly wearer is relaxed, upbeat, worried, agitated, etc. The wristwatch can be used to send alerts to families and/or health care providers using SMS, email and/or instant messenger. Posted on August 4, 2006 Permalink | ShareThis | Buzz up! | 0 Comments

  
  

Take care.

How much for the girl? I want to buy her. Sell her to me.

.

Hi europium,

I kinda had plans for her myself!........

take care.

Stop going there Guys, she's probably got a face that looks like the back of a bus, After a serios accident!!!

You can only see her "Upperworks"!!!

Hi Andy,

I happen to like 'buses'!

Does that mean that you will "ride in/on anything???"

Hi Andy,

YES!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

But trouble is I keep falling off. ;=)

Take care

Before or after?

Hi Andy,

We will have to stop meeting like this!

"Before" unfortunately! Bum! I am getting desperate now..........

Take care

Some interesting stuff here. Thanks for the post.

Harinder