2.1.2 Atomic force microscopy
Atomic force microscope (AFM) imaging, a well-established technique for obtaining information on the surface properties of a sample, was used to determine the collagen preservation in histological skin samples of the mummy.
2-4-µm-thick transverse sections of Zweeloo Woman’s skin were processed as described in section 2.2.1, applied to glass slides, dewaxed and rehydrated in a descending alcohol series. The samples were then analysed using an atomic force microscope (NanoWizard®II, JPK Instruments, Berlin, Germany) operating in intermittent contact mode. Measurements were performed in ambient conditions. Silicon cantilever (BS Tap 300, Budget Sensors, Redding, USA) with typical spring constants of 40 N/m and nominal resonance frequencies of 300 kHz were used. The tip radius was smaller than 10 nm. Image analysis was carried out using SPIP (SPIP 5.0.1.0, Image Metrology, Denmark).