This project aims to establish whether an adapted extraction device is tolerable and will be able to measure chemical signals in baby's ISF. Insight into the chemical profiles found in the skin interstitial fluid (ISF) of healthy and diseased babies will identify signals that can be used to investigate the causes of eczema and propose new preventative strategies and effective treatments.

Specifically, it aims to:

1. Demonstrate that the developed ISF device can be used to extract biomarkers from the skin of babies non-invasively and is tolerable (not causing significant discomfort, bruising, or blister formation).
2. Compare the profile of chemical markers present in the ISF of healthy babies with babies that have developed eczema.
3. Compare the biomarker levels extracted from babies with eczema in lesional and non-lesional skin using the developed ISF device.
4. Compare the microbiome and metabolome profiles from swabs taken from babies with healthy skin and with eczema in lesional and non-lesional skin (exploratory outcome).

Eczema is a skin condition that affects up to 20% of children worldwide, and its numbers are increasing. Our goal is to learn more about eczema by studying how immune signals in the skin differ between babies with eczema and those with healthy skin. To do this, investigators will gently use a non-invasive device to extract a tiny amount of fluid from the top layer of baby's skin(Interstitial Skin Fluid). By studying these samples, investigators want to compare the immune signals of healthy skin and skin affected by eczema. This research aims to deepen our understanding of why eczema causes inflammation and to identify the specific signals involved in this process, particularly in babies.

A total of 30 babies will be recruited, of which 15 will be healthy and 15 have eczema. They will be invited to attend for one visit lasting 1-1.5 hours. During the study visit, clinical information such as demographics, medical history and co-morbidities as well as eczema treatments (where applicable) and other skin care practices will be collected. For babies that have eczema, an eczema area and severity index (EASI) assessment will be conducted. For all participants enrolled onto the study, Interstitial Skin Fluid (ISF) samples will be extracted from the skin using a painless, non-invasive device that is well-tolerated and will not cause any pain or skin damage to the baby. Samples for assessing the skin microbiome will be collected, including skin swabs and tape strips taken in a pain-free manner. Skin barrier function assessments such as Transepidermal water loss (TEWL) will also be performed helping us understand how well the baby's skin holds onto moisture. This is a painless and non-invasive device that doesn't cause any discomfort to the baby.

Inclusion Criteria:

1. Healthy babies and babies with atopic dermatitis up to 6 months old.
2. Ability of parents/guardians/caregivers to provide written informed consent for study participation.
3. Willingness of parents/guardians/caregivers to comply with all study requirements.
4. Parents/guardians/caregivers competent use of English language.

Exclusion Criteria:

1. Parents/guardians/caregivers unable to give informed consent.
2. Preterm birth (defined as birth before 37 completed weeks gestation).
3. Significant inflammatory skin disease at birth.
4. Baby has any other serious health issue.

Babies up to 6 months old with or without eczema that can attend St Thomas' Hospital