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A microelectromechanical systems system (MEMS) electromagnetic swing-type actuator is proposed for an optical fiber switch in this paper. The actuator has a compact size of 5.1 × 5.1 × 5.3 mm3, consisting of two stators, a swing disc (rotator), a rotating shaft, and protective covers. Multi-winding stators and a multipole rotator were adopted to increase the output torque of the actuator. The actuator’s working principle and magnetic circuit were analyzed. The calculation results show that the actuator’s output torque is decisive to the air gap’s magnetic flux density between the stators and the swing disc. NiFe alloy magnetic cores were embedded into each winding center to increase the magnetic flux density. A special manufacturing process was developed for fabricating the stator windings on the ferrite substrate. Six copper windings and NiFe magnetic cores were electroplated onto the ferrite substrates. The corresponding six magnetic poles were configured to the SmCo permanent magnet on the swing disc. A magnetizing device with a particular size was designed and fabricated to magnetize the permanent magnet of the swing disc. The actuator prototype was fabricated, and the performance was tested. The results show that the actuator has a large output torque (40 μNm), fast response (5 ms), and a large swing angle (22°).

Thermal contact resistance plays an important role in many domains, such as microelectronics and nuclear reactors. This paper proposes a more comprehensive model for the prediction of constriction resistance of rough contact between nominally flat surfaces in vacuum. Firstly, a 3D geometrical asperity contact model is proposed based on the analysis of the profile of actual engineering surface. In this model, the contact is not simplified as a rough surface contacting with a perfectly smooth surface, but described as two rough surfaces. Oblique contact is considered and the effects of several parameters such as the shape of the asperity, the depth of interference, and the radial distance between the centerlines of the contacting asperities are investigated. Some mathematical derivations for constriction resistance are performed, and a series of numerical simulations are also carried out, covering a wide range of values of these parameters in practice applications. A comprehensive correlation for constriction resistance as a function of these parameters is finally obtained by nonlinear curve fitting, and it is validated through some comparisons and it can be used to predict more accurately the thermal contact resistance between rough surfaces.

Reducing the switching energy and improving the switching speed of ferroelectrics remain an important goal in the pursuit of electronic devices with ultralow energy consumption and ultrafast response. Molecular ferroelectrics with concise dipole switching mechanism and facile structural tunability are a good platform for manipulating the ferroelectric domains. A methodology is demonstrated to manipulation of ferroelectric domain switching by tailor-made lattice parameters of molecular ferroelectrics, by following which, we succeeded in lowering the threshold electric field and improving the dynamics of ferroelectric switching. Our findings advance the fundamental understanding of microscopic mechanism and provide important insights in controllable tuning of ferroelectric domain switching.