Capillary models for liquid crystal fibers, membranes, films, and drops

Actuation of flexoelectric membranes in viscoelastic fluids with applications to outer hair cells

“…The present theory, model and computations contribute to the evolving fundamental understanding of biological shape actuation through electromechanical couplings [5][6][7][8][9][11][12][13]. Notice that the real and imaginary parts of the transfer function are the same as the average curvature moduli studied previously [18], and can be generalized for higher rheological linear models such as the well-known Jeffrey and Burgers models.…”

“…Both the direct and converse membrane flexoelectric effects are sensor-actuator properties when membrane curvature and polarization are coupled as in nematic LCs. Membrane flexoelectricity due to its inherent sensoractuator capabilities is an area of current interest in soft matter materials [1,7,8,[14][15][16][17][18][19][20][21][22][23][24]. Over the years, much literature has dealt with the problem of measuring flexoelectric coefficients in various LCs [11,13].…”

“…which coincides with E H , and gives 4k c = (K 1 + 8K 24 ),k c = −2K 24 ; the surface gradient is given by the tangential projection of the total gradient: ∇ s (·) ≡ I s · ∇(·), I s = I − kk, since thin layers and membranes behave like LCs, membranes should also exhibit flexoelectricity or couplings between polarization and bending [1][2][3][4]7,11,[17][18][19]. Figure 2 shows a schematic of flexoelectric polarization in rod-like and banana-like molecules and the corresponding membrane flexoelectric polarization; as noted above the physics and modelling are affected by identifying the director field n with the membrane normal k. Using the same approach as above, equation (1.4) gives the membrane polarization P due to membrane bending (∇ s · k): 10) where c f is the membrane flexoelectric coefficient, as indeed found experimentally [4].…”

“…The functioning of outer hair cells (OHCs) in the inner ear involves electric field-driven periodic curvature oscillations of LC elastic membranes that impart momentum and flow to the contacting viscoelastic fluids; the electric field actuation of the LC membrane is known as flexoelectricity [1][2][3][4][5][6][7][8][9][10][11][12]. The key role of OHCs is sound amplification in the presence of viscous dissipation and elastic storage [10].…”

Entropic Behavior of Binary Carbonaceous Mesophases

“…An ideal crystalline solid (Figure 1a In nematic liquid crystals [4] (NLCs), the long molecular axes (u direction in Figure 2) are preferably oriented along a particular direction called the director n (Figure 2). In discotic nematic liquid crystals (DNLCs) the director n is perpendicular to the long axis of discotic molecules ( Figure 2).…”