Analysis of Sweat Secretion and Body Dehydration Monitoring

Reduced physical activity is considered as a risk factor for obesity, diabetes, cancer and depression. A proper exercise program can mitigate cognitive and physical decline associated with ageing. Existing general guidelines for physical activity are not universal or appropriate for every person. A personalized approach based on a subject age and unique combination of different physiological parameters would serve as a solution for finding optimal training protocols for individuals. Hence, monitoring basic physiological and biochemical parameters and obtaining information reflecting the body metabolic state is necessary for health status estimation to develop the abovementioned personally-oriented training protocols. Dehydration Body Monitor (DBM) developed by Spectrophon L.T.D. can measure sweat lost, salt concentration in sweat, and sweating dynamics, which can be used for personal physical status monitoring. This is important not only for controlling appropriate body hydration level but also for keeping kidneys "healthy". Currently, only few DBM tools are available on the market, so there is a growing need for new effective accurate real-time DBM sensors.

The main objective of current study is to estimate the accuracy of Spectrophon DBM incorporated in smartwatch Samsung Gear S2 and sport band Samsung Gear Fit2. The secondary aim of the study is to evaluate the safety-in-use of Spectrophon DBM.

Tested device:

Name: Dehydration Body Monitor; Source: Spectrophon, L.T.D.; Model: SP-DBM Firmware version: 1.5

1. Experimental Design Healthy adults (n=200) in different age and gender groups were recruited for the study. Samsung Gear S2 smartwatch with Spectrophon DBM attached to the bottom of the smartwatch were placed on the right wrist of each participant. At the same time, Samsung Gear Fit2 sport band with Spectrophon DBM attached to the bottom of the band was placed on the left wrist of the participant. Each participant was subjected to moderate physical activity. Data from Samsung Gear S2 and Samsung Gear Fit2 was obtained simultaneously. In parallel, subject weight was also monitored using commercially available digital balancers (Shekel B-200-P).

The evaluation of the measurement accuracy of the Spectrophon DBM was defined as the difference between subject weight change during the exertion (due to sweating and water consumption) and the volume of sweat detected by Spectrophon DBM.

1. Procedures: Participants were weighed prior to the experiment (no clothing after maximal drying) and then subjected to physical activity (walking on the treadmill).

Total duration of study: 90 minutes

5.2 Intensity of exercises:

Participants could choose high or low intensity of exertion:

1. High: up to 6.5km/h;
2. Low: yo to 6.0km/h; 5.3 Data recording: After DBM application was activated, DBM started recording data (sweat rate and total salt in sweat) every 20 sec. and automatically saved results into archive on a mobile phone linked to Samsung Gear S2 or Samsung Gear Fit2 by Bluetooth. Manual recording of data was conducted during breaks Participants were also weighed during each break (no clothing after maximal drying).

5.4. Drinking During the procedure, subjects could drink up to 500 ml of water. The weight of the bottle was measured and recorded after drinking during breaks. The difference was subtracted to the weight loss calculation.

5.5 Restrictions:

In this experiment, the following was avoided:

1. Urination during test (empty before T0)
2. Weight loss should not exceed 2%

Participants could cancel the experiment at any point of the procedure if desired.