Casimir force densities, i.e., force per area, become very large if two solid material surfaces come closer together to each other than 10 nm. In most cases, the forces are attractive. In some cases, they can be repulsive depending on the solid materials and the fluid medium in between. This review provides an overview of experimental and theoretical studies that have been performed and focuses on four main aspects: (i) the combinations of different materials, (ii) the considered geometries, (iii) the applied experimental measurement methodologies and (iv) a novel self-assembly methodology based on Casimir forces. Briefly reviewed is also the influence of additional parameters such as temperature, conductivity, and surface roughness. The Casimir effect opens many application possibilities in microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS), where an overview is also provided. The knowledge generation in this fascinating field requires interdisciplinary approaches to generate synergetic effects between technological fabrication metrology, theoretical simulations, the establishment of adequate models, artificial intelligence, and machine learning. Finally, multiple applications are addressed as a research roadmap.

For different metals and varying geometries, this paper presents simulations of electrostatically actuated MEMS cantilevers regarding their influence on pull-in voltage and actuation speed. Three-dimensional electromechanical modeling including many non-linearities has been performed to study some static but mainly dynamic features. The results show that the involved parameters have different influences on the actuation speed and pull-in voltage: lower length, higher thickness as well as lower density and higher Young’s modulus of material diminish the actuation time, while longer length, smaller thickness, and smaller Young’s modulus reduce the actuation voltages. Shorter actuation times and smaller actuation voltages cannot be obtained and optimized simultaneously. Different metals such as Au, Ag, Cu, Ti, Ni, Al, W, Cr, Ta, and Mo as well as artificial metals are studied and compared. In this study, Al is found to be the best material for achieving shorter actuation times and smaller actuation voltages. The design rules of MEMS cantilevers are derived considering the large variety of studied parameters. Many involved non-linearities are discussed in detail influencing the MEMS dynamics. Finally, the actuation times are related to the existing experimental actuation times of optical MEMS shutters and MEMS cantilevers.

The advancement of smartphones with multiple built-in sensors facilitates the development of crowdsourcing-based indoor map construction and localization. This paper proposes a crowdsourcing-based indoor semantic map construction and localization method using graph optimization. Using waypoints, semantic landmarks, and Wi-Fi landmarks as nodes and the relevance between waypoints and landmarks (i.e., waypoint–waypoint, waypoint–semantic, waypoint–Wi-Fi, semantic–semantic, and Wi-Fi–Wi-Fi) as edges, the optimization graph is constructed. Initializing the venue map is the single-track semantic map with the highest quality, as determined by a proposed map quality evaluation function. The aligned venue and candidate maps are optimized while satisfying the constraints, with the candidate map exhibiting the highest degree of similarity to the venue map. The lightweight venue map is then updated in terms of waypoint and landmark attributes, as well as the relationship between waypoints and landmarks. To determine a pedestrian’s location on a venue map, similarities between a local map and a venue map are evaluated. Experiments conducted in an office building and shopping mall scenes demonstrate that crowdsourcing-based venue maps are superior to single-track semantic maps. Additionally, the landmark matching-based localization method can achieve a mean localization error of less than 0.5 m on the venue map, compared to 0.6 m in a single-track semantic map.

The paper presents the design and technological fabrication process of Yin or Yang-shaped, micron-sized electromechanical system (MEMS) elements displaying asymmetric hollow cylinders with two different curvatures of the cylinder shell. By adapting the process steps, two neighboring shutter MEMS elements can either be attached to each other to create asymmetric hollow cylinders or remain disconnected to form curled cylindrical or ellipsoidal tubes or tube fractions. A novel 3D self-organization process has been developed to connect two neighboring shutter elements, exploiting surface tension forces via a sequential drying process. The process conditions have been analyzed and optimized to fabricate the two different geometries of the MEMS elements. The resulting MEMS system elements were characterized by focused ion beam and scanning electron microscopy. The contribution of Casimir force, van der Waals force, and other physical interfacial forces are discussed in the formation of the asymmetric hollow cylinders.

This study aimed to describe the rate of cataract surgical coverage (CSC) and the quality-of-life (QoL) outcomes after cataract surgery in rural China. Cross-sectional study. A clustered, random sampling procedure was used to select 7557 Chinese patients aged 30 years and older from Handan, China. Comprehensive eye examinations, including standardized refraction and classification of lens characteristics, were offered to all eligible subjects. Visual impairment was defined as any individual with presenting visual acuity of less than 20/60 in the better-seeing eye. The main outcome measures were CSC rate and a summary measure assessing QoL in visually impaired (VI) participants. Of 5592 participants older than 40 years, there were 41 cataract patients operated on and 54 VI cataract patients not operated on. The CSC rate among individuals with VI was 43.2%. Older age was significantly negatively associated with a history of cataract surgery (adjusted odds ratio, 0.44 per 10-year increase in age; 95% confidence interval, 0.26–0.74). Women were less likely to have had cataract surgery compared with men, although not significantly (adjusted odds ratio, 0.44; 95% confidence interval, 0.17–1.12). The QoL summary measure was significantly better in the cataract group operated on than that not operated on (P < 0.01). There is a large unmet need for cataract surgery in rural Handan, China. Those who had surgery were more likely to have better QoL outcomes than those who did not. There is a potential need to promote cataract surgery and develop age- and sex-sensitive interventions in rural China.

This article presents the electrostatic actuation performance of micromirror arrays for intelligent active daylight control and energy management in green buildings using a capacitive–voltage (C-V) measurement technique. In order to understand how geometric hinge parameters, initial opening angles, and materials affect the overall efficiency and functionality of the system, micromirror arrays have been analyzed using C-V measurements considering (i) full and broken hinge structures, (ii) 90° and 130° initial tilt angles (Φ), and (iii) different material layer combinations. The measurement results indicate that both an increase in the Young’s modulus of the applied materials and increasing the initial tilt angles increase the threshold voltages during the closing process of the micromirrors.