The vibrations of the thin wall depend on its clamping and material properties, the fluid properties on both sides of the wall, and the device geometry. Due to the complexity of the boundary conditions it is difficult to analytically compute the exact vibrational modes, which nevertheless can be approximated with a two-dimensional plate model. The force responsible for attracting small (relative to the acoustic wavelength), spherical, and solid particles towards the wall is called acoustic radiation force (ARF). For an inviscid fluid, it is given by the negative gradient of the Gor'kov potential 56