Science Buddies: "Ask an Expert"

How feasible is sodium loss estimation and tracking sweat rate from a skin sensor? My niece is working on her high school science project and she decided to focus on exercise and how much you sweat during various types of exercise modalities. (ie Yoga vs Cycling vs Zumba class etc.) She wants to figure out a way to measure someone's sweat rate, what they lose or deplete (electrolytes and minerals in the body) while exercising vs someone's baseline. And how to know when someone is under hydrated. (I mentioned to her chapped lips) I know triathletes use advanced sweat testing where you send in a patch or kit for analysis.. but that isn't really a realistic option for most and for this project... Is it feasible to track such sweat and body metrics from a sensor with light?

Good morning,

Here is a formula from CDC to calculate Sweat rate:
https://www.cdc.gov/nceh/hsb/extreme/He ... lation.pdf
It seems this can be done with simple instruments: accurate weighing scale, measuring container etc. Be very careful and record any fluid intake.
Here are more instructions about the method:
https://truesport.org/hydration/calcula ... weat-rate/

There don't seem to be any sodium sensors that can measure concentration by light reflection. There are Ion meters such as :https://www.abqindustrial.net/store/hor ... 0mzg1qu53k
but cost is likely prohibitive.

Science buddies has this project where you make a simple conductance sensor:
https://www.sciencebuddies.org/science- ... drink#help
It measures conductance which correlates with electrolyte concentration in the liquids. It measures ALL electrolytes so no exact sodium levels will be obtained. Another caveat is coming up with a way to collect enough sweat for this kit to work.

In Science olympiad, students construct a water Salinometer with use of straw and clay: https://www.soinc.org/sites/default/fil ... er12_0.pdf

Some have constructed an arduino based salinometer.

Constructing her own device will make this project even more interesting and creative. Sweat collection will be a problem: One of the methods is using gauze pads applied to the skin to collect sweat for analysis. To extract the sweat from the absorbent pad, the pad can be either: 1) placed in a filter tube and subsequently centrifuged at ~3000 rpm for ~10 min (e.g., if planning to send to a laboratory for analysis) or 2) placed in the barrel of a plastic syringe and squeezed with a plunger (e.g., if planning to conduct analysis in the field). Here is the reference on this method:
https://www.gssiweb.org/sports-science- ... hatgpt.com

Good luck with this project!
Anya