Study of tribological properties of human buccal epithelium cell membranes using probe microscopy

In this work demostrates a unique method for determining the absolute value of the friction force of a nanoobject on the surface of a cell membrane using atomic force microscopy. The tribological properties of membranes of adult human buccal epithelium cells in the presence of a protective adsorption buffer layer of ~ 100 nm on their surface were studied using atomic force microscopy in the contact scanning mode. Local mapping of the tribological characteristics of the surface was carried out, viz. friction FL = FL(x, y) and adhesion Fadh = Fadh(x, y) forces were measured. Studies of the friction force Ffr on the membrane surface at the nanolevel showed that its value varies discretely with an interval equal to lLF ≈ 100 nm. It was shown that such discreteness is determined by the interval lLF of the action of adhesive forces Fadh and indicates the fractal nature of the functional dependence of the friction force on the coordinate Ffr = Ffr(x). Thus, for nano-objects with dimensions ≤ lLF, the absolute value of Ffr decreases according to a power law with an increase in the size of the object, which contradicts the similar dependence of the friction force for macro-objects in the global approximation

Physical nature of size effects in TiAlNiAu/GaN ohmic contacts to AlGaN/GaN heteroepitaxial structures

The size effect observed in TiAlNiAu/GaN ohmic contacts (OCs) makes itself evident in the dependence of their relative electrical characteristics R (SH) , R (SK) , rho and geometrical parameter L (T) on the LTLM test line width W-k . The paper explores the geometry of relief (topography) irregularities and their interface conductivity, indicating the great significance of the fractal geometry for the description of the electrophysical and device characteristics. The regularities discovered can be of great practical importance in terms of OC development and optimization for micro-/nanoelectronics demands

AFM methods for studying the morphology and micromechanical properties of the membrane of human buccal epithelium cell

Abstract Using AFM methods in air under normal conditions in a wide range of local force effects ( $${F}_{const}$$ F const  21 nN) stimulation ( $${F}_{const}$$ F const ) is a non-trivial selective process and exhibits a correspondingly elastic ( $$K=$$ K = 67.4 N/m), active ( $$K=$$ K = 80.2 N/m) and passive ( $$K=$$ K = 84.5 N/m) responses. $$K=K({F}_{const})$$ K = K ( F const ) and $$E=E({F}_{const})$$ E = E ( F const ) depend on $${F}_{const}$$ F const . Having undergone slight plastic deformations $${\Delta h}_{stiff}$$ Δ h stiff < 300 nm, the membrane is capable of restoring its shape. We mapped ( $$E=E(x;y)$$ E = E ( x ; y ) , $${D}_{f}$$ D f = 2.56; $${\Delta h}_{dfrm}={\Delta h}_{dfrm}(x;y)$$ Δ h dfrm = Δ h dfrm ( x ; y ) , $${D}_{f}$$ D f = 2.68; $${\Delta h}_{stiff}={\Delta h}_{stiff}(x;y)$$ Δ h stiff = Δ h stiff ( x ; y ) , $${D}_{f }$$ D f = 2.42, $$A=A\left(x;y\right)$$ A = A x ; y and $${F}_{adh}={F}_{adh}(x;y)$$ F adh = F adh ( x ; y ) ) indicating its complex cavernous structure