Macro-scale, hemispherical-shaped resonating gyroscopes are used in high-precision motion and navigation applications. In these gyroscopes, a 3D wine-glass, hemispherical-shaped resonating structure is used as the main sensing element. Motivated by the success of macroscale hemispherical shape gyroscopes, many microscale hemispherical-shaped resonators have been produced due to the rapid advancement in semiconductor-based microfabrication technologies. The dynamic performance of hemispherical resonators depends on the degree of symmetry, uniformity of thickness, and surface smoothness, which, in turn, depend on the type of materials and fabrication methods. The main aim of this review paper is to summarize the materials, characterization and fabrication methods reported in the literature for the fabrication of microscale hemispherical resonator gyroscopes (µHRGs). The theory behind the development of HRGs is described and advancements in the fabrication of microscale HRGs through various semiconductor-based fabrication techniques are outlined. The integration of electrodes with the hemispherical structure for electrical transduction using other materials and fabrication methods is also presented. A comparison of different materials and methods of fabrication from the point of view of device characteristics and dynamic performance is discussed. This review can help researchers in their future research and engineers to select the materials and methods for µHRG development.

A hydroelastic hybrid model is developed to simulate the fluid–structure interaction in water entry problems using the partitioned approach. The interactions between a flat plate and the water are modeled by a hydroelastic model using explicit and implicit couplings. Both couplings are unstable due to numerical instability associated with the fluid added mass. To overcome the instability, an extended Wagner’s model is combined with the hydroelastic model, and a hybrid model is developed. The extended Wagner’s model is the extension of the classical Wagner’s model that is used to estimate the fluid inertial, damping, and restoring forces of a flexible plate within the potential flow theory. The fluid flow is described by the unsteady Reynolds averaged Navier–Stokes equations in the hydroelastic model and hybrid model. The longitudinal bending of the plate is approximated by the strips in all models. The hybrid model is verified and validated by comparing the available computational and semi-analytical results of the vertical and oblique water entries for the plate with different boundary conditions. The results show that the hybrid model is stable, accurate, and simple to implement. This two-dimensional model can be generalized to the third dimension and applied for more complex structures.