The goal of this interventional clinical trial is to investigate whether combining photoplethysmography (PPG) signals with accelerometer (ACC), gyroscope (GYR), sound, and electrocardiography (ECG) derived smartphone data provides additional insights into the cardiac condition of individuals with and without atrial fibrillation (AF).

Inclusion Criteria:

Inclusion criteria applicable for all groups:

• At least 18 years old
• Participants must have the ability to understand and provide written informed consent
• Participants must have the ability to understand Dutch

Group specific inclusion criteria:

Group 1: Healthy volunteers

• No cardiac conditions based on medical history.

Group 2: Cardiology patients

• Patients at the consultation or ambulatory unit of Cardiology (pre- cardioversion, pre-pulmonary vein isolation) with AF.
• Patients without AF but with a current cardiac condition (e.g. heart failure with a reduced or preserved ejection fraction) or a history of a cardiac condition (e.g. history of myocardial infarction).

Exclusion Criteria:

• Individuals with unnaturally coloured fingers (i.e. tattoos, ink); this may weaken the signal and may interfere with the effectiveness of the device
• Persons with conditions causing tremors or the inability to hold their hand still for at least 60 seconds (e.g. Parkinson or dementia) as, in this case, the device may not be able to accurately process a measurement
• Persons with reduced blood flow in the fingertips (e.g. perniosis or severe callus formation) as the device may not be able to detect the intensity variations induced by the blood flow
• Persons that have a disability to perform the measurements according to the instructions for use
• Persons with cardiac pacemakers, implantable cardioverter-defibrillators, or other implanted electronic devices as these can control the natural heart rhythm