2.2 Technical equipment
2.2.1 LC-OCT
Detailed information on the LC-OCT device (DeepLiveTM, DAMAE Medical, France) used for image acquisition in this study can be found in[28]. Briefly, it is a Linnik interferometer-based imaging system with line illumination by supercontinuum laser at a central wavelength around 800 nm. A water-immersion microscope objective with a numerical aperture NA = 0.5 is incorporated in each arm of the interferometer. Backscattered spatially-coherent light is detected using a line camera. By in-depth scanning (along z -axis) during acquisition of horizontal section images with a field of view of 1.2 mm × 0.5 mm (x × y ), a stack of images can be compiled to obtain a 3D image of the tissuein situ with axial and lateral resolutions of less than 1.3 μm and a maximum penetration depth (z ) of about 500 μm.
2.2.2 Physical permeability enhancers
Therapeutic ultrasound (Pulson 100, Gymna, Belgium) was used as a physical permeability enhancer as it allows to increase the skin permeability for OCA.[25] The duty cycle was 100%, the frequency 1 MHz and the power density 1 W/cm2. Also, the skin microdermabrasion device (Philips VisaCare, Philips, Netherlands) was used. This procedure is commonly applied in cosmetology and involves the abrasion of stratum corneum (SC) layer that leads to increased penetration rate of OCA into the skin.