The electromagnetic (EM) properties of metasurfaces depend on both structural design and material properties. microelectromechanical systems (MEMS) technology offers an approach for tuning metasurface EM properties by structural reconfiguration. In the past 10 years, vast applications have been demonstrated based on MEMS metasurfaces, which proved to have merits including, large tunability, fast speed, small size, light weight, capability of dense integration, and compatibility of cost-effective fabrication process. Here, recent advances in MEMS metasurface applications are reviewed and categorized based on the tuning mechanisms, operation band and tuning speed. As an example, the pros and cons of MEMS metasurfaces for tunable lens applications are discussed and compared with traditional tunable lens technologies followed by the summary and outlook.

Design of multiple-feed lens antennas requires multivariate and multi-objective optimization processes, which can be accelerated by PSO algorithms. However, the PSO algorithm often fails to achieve optimal results with limited computation resources since spaces of candidate solutions are quite large for lens antenna designs. This paper presents a design paradigm for multiple-feed lens antennas based on a physics-assisted particle swarm optimization (PA-PSO) algorithm, which guides the swarm of particles based on laws of physics. As a proof of concept, a design of compact metalens antenna is proposed, which measures unprecedented performances, such as a field of view at ±55°, a 21.7 dBi gain with a flatness within 4 dB, a 3-dB bandwidth >12°, and a compact design with a f-number of 0.2. The proposed PA-PSO algorithm reaches the optimal results 6 times faster than the ordinary PSO algorithm, which endows promising applications in the multivariate and multi-objective optimization processes, including but not limited to metalens antenna designs.