Body temperature is one of the markers of biological rhythms. The precise determination of the functioning of the biological clock for an individual is essential to understanding his physiological state at a given time. This condition is dependent on the "timing" of its central clock on the time scale (chronotype). The provision of a simple-to-use (F2D cuff), non-invasive and time-dependable temperature tool and the creation of appropriate algorithms would allow access to the operation of the central clock and open up many therapeutic applications.

While the measurement of body temperature is one of the first self-diagnosis gestures at home, it is unanimously agreed by healthcare professionals that the measurement of non-invasive body temperature performed both in a hospital setting, in the office, that at home is very imprecise, or even false. As a result, temperature is only an indicator and is of little interest. Only the rectal thermometer and the telemetric capsule (e-CELSIUS® capsule to be ingested that allows a reliable and continuous measurement of gastrointestinal temperature without the intervention of the caregiver) are reliable tools, but they remain invasive and do not always allow for fully reliable follow-up over time. We propose to develop an algorithm integrated in an external, non-invasive cuff, allowing the continuous recording of body temperature.

In addition, body temperature is one of the markers of biological rhythms. The precise determination of the functioning of the biological clock for an individual is essential to understanding his physiological state at a given time. This condition is dependent on the "timing" of its central clock on the time scale (chronotype). The provision of a simple-to-use (F2D cuff), non-invasive and time-dependable temperature tool and the creation of appropriate algorithms would allow access to the operation of the central clock and open up many therapeutic applications.

This work proposes to validate the tool on the one hand and on the other to use this tool to produce the elements necessary for monitoring the functioning of the central biological clock.

Inclusion Criteria:

• Healthy male or female,
• Between 18 and 40 years of age for the WP I and II phases, and between 18 and 80 years of age for the WP III phase,
• Having an BMI within the range [18.5; 24.9] kg/m² for the Work Package I and II phases, and between [18.5; 34.9] kg/m² for the Work Package III phase,
• Beneficiary of the social security,
• Provided informed consent for participation in the study.

Exclusion Criteria:

• Presenting an acute pathology,
• Chronic pathology not followed and balanced,
• Having intestinal disorders (diverticles, disorders of the motility of the digestive tract, ...) or having undergone surgery at the gastrointestinal level,
• With known swallowing disorders,
• Having an alcohol dependence (more than 28 alcohol units per week), benzodiazepines or any illicit product,
• Smoking more than 5 cigarettes per day,
• Working nights or shift work,
• Simultaneous participation in other clinical research or participation in another clinical study for which the exclusion period has not ended.