The study aims to assess the usability and safety of use of MuCopilot, a smartphone application that measures objective data on lung function, global exercise capacity and patient reported outcomes of patients with Cystic Fibrosis (CF). These data are collected during unsupervised digital tests performed in the patient's home environment between consultations.

The primary objective is to validate the usability and safety of use, in order to assure that the patients use the medical device as intended without any unacceptable error of use and without unacceptable risk.

The study will include 17 CF patients and will be conducted in France. They will participate in 1 inclusion visit and 1 visit in-clinic (1h30).

Patients will be able to download the free MuCopilot mobile application. During the visit, patients will complete 3 digital tests in order to monitor CF functions (cough, dyspnea & walking) and 1 symptom questionnaire.

Inclusion Criteria:

• Aged ⩾ 18 years old
• Patients diagnosed with cystic fibrosis
• Enrolled in or benefiting of a Social Security program
• Having read the information sheet and signed the informed consent form
• Owning a personal smartphone which version is above 14 for IOS and 8 for Android included with a good internet connexion
• Able to read French and understand pictograms on a smartphone app

Exclusion Criteria:

• History of lung transplantation
• Pregnant women and women who are breastfeeding
• Any medical condition that could interfere with the proper conduct and results of the study (clinician's judgement)
• Illiterate in French
• Inability to use a smartphone or MuCopilot application
• Person under legal protection (including guardianship or curatorship)