Atomic force microscope protocols for characterising the elastoviscoplastic biomechanical properties of corneocytes

Corneocytes, the fundamental units of the epidermis outer layer, are essential for skin's barrier function. This study employs Atomic Force Microscopy (AFM) to explore the topographical and biomechanical properties of volar forearm cells. A detailed protocol is presented to eliminate experimental artefacts that have led to variability in reported Young's moduli. The goal is to create a consistent material model reflecting the elastic and inelastic behaviour of corneocytes. Using standard sharp AFM probes allows for accurate cell topography capture and targeted indentation for mechanical property measurements without changing probes. The methodology for interpreting mechanical data from sharp indenters is also addressed. Results indicate that corneocytes in a dry state exhibit Young's moduli similar to glassy organic polymers and demonstrate viscoplastic behaviour, described by the Herschel-Bulkley model. These detailed protocols enhance our understanding of skin biomechanics, potentially guiding advancements in biomimetic materials and dermatological studies.