This paper introduces the design and manufacturing technology of aerospace microelectromechanical systems (MEMS) characterized by high performance, multi-variety, and small batch. Moreover, several kinds of special MEMS devices with high precision, high reliability, and environmental adaptability, as well as their typical applications in the fields of aeronautics and aerospace, are presented.

In this paper a detailed analysis on the self-oscillation system that is used for the resonant pressure sensor is presented. The stability and transient response of the system are investigated through a theoretical model, which is verified by experiment. This analysis provides an approach to optimize the parameters of the control system to get a short settling time and a stable system in the full pressure scale. The sensor chip is fabricated using a commercially available silicon-on-insulator wafer. By optimizing the parameters, the self-oscillation system for the sensor works well and the setting time is less than 300 ms in full pressure scale. The calibration result shows that the resonant pressure sensor has a nonlinearity of 0.045 %FS, a hysteresis error of 0.14 %FS, and a repeatability error of 0.18 %FS.

Understanding the function of nanoscale structure morphology in ice adhesion properties is important in deicing applications. The correlation between ice adhesion and nanowire morphology as well as the corresponding ice shear fracture mechanism are presented for the first time. Ice adhesion on nanowires was measured using a tangential ice-detaching instrument that was developed in-house. Stress analysis was performed using a COMSOL software. Nanowire surface shifted from Wenzel to Cassie transition and Cassie wetting states when the nanowire length was increased. Tangential ice-detaching forces were greater on the hydrophilic surface than those on the hydrophobic surface. Ice–ice internal shear fracture occurred on the ice and force probe contact area at the Wenzel state or on the ice and nanowire contact area at Cassie transition and Cassie state. Different lengths of nanowires caused different wetting states; thus, different fracture areas were formed, which resulted in different tangential ice-detaching forces. This paper presents a new way of tailoring surface ice adhesion via rational design of nanowire morphology with different wetting states.Keywords: ice adhesion; morphology; nanowire; shear fracture; stress analysis; wetting state

Numerical simulation has become an effective way to design and optimize micromachined thermal sensors. To improve the speed of development process, fast simulation is indispensable. This paper investigates compact models, which are accurate low order representations of high order finite element models, for micromachined thermal sensors. Because the thermal field and the electric field act on and influence each other, the compact models should be established from the thermoelectric coupled full models. Thermoelectric coupling and temperature dependent resistivity make the problems strong nonlinearity. Therefore a powerful nonlinear model order reduction method, named trajectory piecewise-linear (TPWL) method, is employed. Its core idea is approximating the nonlinear model piecewise-linearly along a training trajectory. The performance of the TPWL method and fast TPWL method are compared. And the effects of linearization point number and local reduced basis order on accuracy, efficiency and size of the TPWL compact models are studied. Moreover, the expandability of the TPWL compact models is also discussed. Results show that the TPWL compact models are suitable for the design and optimization of micromachined thermal sensors.

A new type of flexible balloon actuator for active flow control is developed. Compared with the existing balloon actuator with a rigid substrate, it possesses total structural flexibility and perfect air-tightness even with internal high pressure gas. Finite element method is used to analyze the mechanical properties of elastic membrane. The maximum deflection of the balloon membrane is calculated to be 1.5 mm. To investigate the control ability of the actuators, numerical simulation is carried out. The results show that the actuators can dramatically alter the flow field within the boundary layer. Flight test shows that the inflated balloon actuators lead to local flow separation. The imbalance of localized pressure on the airfoils induces an extra rolling moment and the rolling angle of the UAV is changed about 30°.

An effective fabrication method combining deep reactive ion etching and galvanic etching for silicon micro–nano hierarchical structures is presented in this paper. The method can partially control the morphology of the nanostructures and enables us to investigate the effects of geometry changes on the properties of the surfaces. The forming mechanism of silicon nanostructures based on silver nanoparticle galvanic etching was illustrated and the effects of process parameters on the surface morphology were thoroughly discussed. It is found that process parameters have more impact on the height of silicon nanostructure than its diameter. Contact angle measurement and tilting/dropping test results show that as-prepared silicon surfaces with hierarchical structures were superhydrophobic. What’s more, two-scale model composed of micropillar arrays and nanopillar arrays was proposed to study the wettability of the surface with hierarchical structures. Wettability analysis results indicate that the superhydrophobic surface may demonstrate a hybrid state at which water sits on nanoscale pillars and immerses into microscale grooves partially.Graphical abstractSuperhydrophobic silicon surfaces with micro–nano hierarchical structures were fabricated by deep reactive ion etching and galvanic etching. Wettability analysis using two-scale model composed of micropillar and nanopillar arrays indicated that superhydrophobic surface may demonstrate a hybrid wetting state.Highlights► A novel fabrication method for silicon hierarchical structures is presented. ► The forming mechanism and the effects of process parameters were discussed. ► CA measurement and tilting/dropping test show the surfaces were superhydrophobic. ► Two-scale model composed of micropillar and nanopillar arrays was proposed. ► Superhydrophobic surface may demonstrate a hybrid wetting state.

A new micro programmable blazed grating (μPBG) was designed, fabricated and characterized using the two-layer polysilicon surface micromachining process. The μPBG presented is simple in structure and has the capability of continuous spectral tuning for a wide wavelength range. To maximize the operational blazed angle, dimple structure was adopted as the key component for grating slats, and its height was close to the air gap. By the measurements, the developed μPBG sample can reach a maximum blazed angle of ∼5.19° at a driving voltage of 112 V. Accordingly, the blazed wavelength can reach a mid-infrared wavelength of 4.88 μm. Then, a preliminary experiment to investigate the feasibility of multispectral imaging by using the developed μPBG as the core dispersing element was performed, and the results are encouraging. The advantages of the proposed method for multi-spectral imaging are discussed, and some suggestions for further research are also put forward.

A simple numerical method based on MATLAB (The MathWorks, Inc.) is presented for studying the far-field diffraction of some optical MEMS devices with a large array and complex element geometry. The method avoids the theoretical solution by defining the working surfaces according to different apertures. Through a practical example of a grating optical modulator, the experimental tests are in good agreement with the simulation performed by using the proposed method. Then, some other optical MEMS devices with different structure configurations are also simulated. All these results reveal that the method proposed is efficient and effective, yet easy to operate. It is extremely suitable for simulating and analyzing such optical MEMS devices with planar reflective or transmissive optical working surfaces.

In this paper, a parametric model order reduction (PMOR) method was presented to firstly extract the macromodels of squeeze film damping in perforated microstructures. The various design variables such as flow impedance of perforations, viscosity, ambient pressure, plate thickness and gap separation were preserved in the model order reduction (MOR) process. Thus when these parameters change, the extracted parametric macromodels could be reused parametrically instead of repeating the time-consuming MOR process in the traditional way. A micromachined capacitive accelerometer was used to demonstrate the feasibility and efficiency of the PMOR method for the squeeze film damping in perforated microstructures. The maximum relative error is less than 0.3% while the computational efficiency improves about 11 times compared with finite element method.

The prototype of a new micro programmable blazed grating driven electrostatically was fabricated using a two-layer polysilicon surface micromachining process. And initially, to characterize its electromechanical performances, such as the driving voltage versus displacement relationship, frequency response and step response, the laser Doppler vibrometry was employed. The measured results reveal the pull-in voltage of 110–115 V, resonant frequency of 78 KHz, quality factor of 2.89, adjusting time of 12 μs, and damping ratio of ~0.68 for the achieved grating sample. As a result, the grating functions well electromechanically. As for its optical performances, a number of optical experiments are in progress.

This paper presents one MEMS design tool with a total six of design flows, which makes it possible that the MEMS designers choose the most suitable design flow for their specific devices. The design tool is divided into three levels and interconnected by six interfaces. The three levels are the lumped-element model based system level, finite element analysis based device level and process level, which cover nearly all modeling and simulation functions for MEMS design. The six interfaces are proposed to automatically transmit the design data between every two levels, thus the maximal six design flows could be realized. The interfaces take the netlist, solid model and layout as the data inlet and outlet for the system, device and process level respectively. The realization of these interfaces are presented and verified by design examples, which also proves that enough flexibility in the design flow can really increase the design efficiency.

Knowledge of wall shear stress is essential for understanding the dynamics of fluid flow, and its measurement holds great importance for investigating and controlling near wall turbulence and flow separation in aerodynamic control. Based on the well-established principle of thermal anemometry, this paper describes an array of thin film sensors on a flexible polyimide substrate. Then, Computational Fluid Dynamics (CFD) simulations were performed to estimate the corresponding shear stress distribution within the column cylinder aerofoil at flow conditions is the velocity 17.3 m/s. In wind tunnel tests, by disposed the two sensor arrays output signals by the sensors output voltages means and RMS values, the result proved these flexible arrays could detect the location of the fluid separation point roughly.

A silicon-based micro-machined, floating element sensor for wall shear-stress measurement has been developed. Sensor with the dimension of 4×3×0.5 mm3 has been fabricated by inductively coupled plasma (ICP) etching techniques with single mask. An optical system was designed to identify whether there is defect in the structure of the fabricated sensor. Detection of the floating element motion induced by shear stress of fluid is accomplished using differential capacitance measurement. A special package was used to reduce the parasitic capacitance and realize flush mounted between the sensor and the wall. Calibration tests were carried out in a laminar flow channel; the result indicates that the sensitivity of the sensor is measured to be 27 mv/Pa. The measured non-linearity is less than 3.4% while the repeatability is within 4.9% in the regime of 0–35 Pa.Graphical AbstractDownload full-size imageHighlights► We design a structure of floating element shear stress sensor. ► We develop a fabrication process with single mask to fabricate the sensor. ► An optical system can detect the structure of the sensor. ► Special packaging method realizes flush mounting between the sensor and wall. ► Calibration experiment indicates the feasibility of the shear stress sensor.