How to detect sweat levels, humidity sensor maybe?

rwgast_logicdesign

ould a humidity sensor be strapped on the body to detect how much is sweating, or would direct contact to water like this just give faulty readings? Maybe im barking up the wrong tree, if so anyone knoww of a sensor i could use to try and measure prespiration?

NWCCTV

You might find what you are looking for here: http://www.digikey.com/product-search/en/sensors-transducers/humidity-moisture/1966708?k=Sensors,%20Transducers

I don't think a humidity sensor would give very accurate readings for this type of use.

SRLM

You might be able to measure the resistance of the skin surface, and use that to determine sweat levels.

rwgast_logicdesign

Well I was hoping maybe you could stick a humidity sensor next to the skin, and somehow correlate its value in to a meaningful measurement for sweat. But what i got to thinking about ot what happens if theres enough sweat to saturate the sensor, obviously it will give a max reading but will that break it?

thank ncc, id acually only looked at the parallax offerings. In this case money isnt a huge issue within reason (ie probably not over 60 bucks). What is an issue is spending money on something that doesnt work. I thought a 9 dollar parallax sensor may be a good starting point for tests, to see if forking real money over is worth it.

SRLM, yes testing resistance may be the best way. It wont give a highly accurate reading but it should give a fairly ball park figure which may be good enough with other sensor data taken in to consideration.

Leon

Skin conductance is generally used to measure emotional responses, using suitable electrodes. The same techniques could be used.

erco

People's sweat level's vary drastically, which will confound any attempt at standard calibration. You might be able to make some relative measurements to confirm exertion, but a heavy sweater will saturate a sensor and peg your sweat-ometer pretty quickly.

Phil Pilgrim (PhiPi)

I think a humidity sensor could work if properly positioned. What I envision is a square bandage with adhesive around all four edges and a Gore-Tex membrane in place of the gauze pad. On the non-skin side of the Gore-Tex would be a vented bubble containing a humidity sensor. Sweat from the skin would diffuse through the Gore-Tex as water vapor and mix with the air in the bubble. The humidity inside the bubble would be a function of the inward diffusion rate through the Gore-Tex and the outward diffusion rate through the vent.

-Phil

Beau Schwabe

What about a simple galvanic sensor approach using the body as a wheat-stone-bridge? .... alternatively a more modern approach would be to use TWO humidity sensors differentially to one another at different locations on the body. One location less likely to sweat, the other location more likely to sweat. Under 'normal' relaxed conditions, both sensors would have close to the same reading. Under distress, they would show a considerable difference to one another.

Cats92

This reminds me of an old diagnosis method used for cystic fibrosis : the sweat test (now a genetic test is used).

Perhaps google for this test may help.

http://en.wikipedia.org/wiki/Sweat_test

Such google search shows that the quantity and composition of sweat may vary widely , in physiology and pathology.

BTW : Bioingeneers have designed a lot of quick diagnostic tests in past years , is it necessary to add more ?