Microsystem Technologies

In this paper a miniature piezoelectric energy harvester (PEH) with clamped–clamped beam and mass loading at the center is introduced which has more consistency against off-axis accelerations and more efficiency in comparison to other cantilever PEH’s. The beams consist of different layers of Si, piezoelectric, and insulators based on MEMS technology that vibrates by applying an external force to the fixed frame. Due to beam vibration, variable stress is applied to the AlN piezoelectric and a potential difference is created at the output terminals. AlN is deposited on clamped–clamped beams in such a way that produce more stress points which cause more power to be generated in comparison to other cantilever beam PEH’s with about same dimensions. A partial differential equations (PDE) describing the flexural wave propagating in the multi-morph clamped–clamped beam are solved as theoretical calculations for inherent frequency estimation and is confirmed by simulation results. The obtained inherent frequency is 42 Hz which with 1 g (g = 9.81 m/s2) acceleration produces 4 V and 80 µW maximum electrical peak power that can be used in the node of low-power consumption wireless sensor node for wireless sensor network (WSN) applications.

Chức năng của các bề mặt, đặc biệt là cho các ứng dụng nhiệt động lực học, có thể được nâng cao nhờ vào việc sửa đổi bề mặt cụ thể. Do đó, nghiên cứu này điều tra các cấu trúc bề mặt được chọn lọc khác nhau và tác động của chúng đối với khả năng truyền nhiệt. Các hình học vi mô cụ thể là trọng tâm của nghiên cứu này. Một quy trình thiết kế có hệ thống và xác định các cấu trúc vi nhiệt động lực học phù hợp thông qua mô phỏng đa vật lý FEM đã được thực hiện. Sau đó, các cấu trúc được điều tra đã được chế tạo bằng cách áp dụng công nghệ gia công điện hóa và gia công bằng tia laser. Hơn nữa, một phân tích có hệ thống về độ chính xác và chất lượng bề mặt đã được tiến hành, điều này nhấn mạnh tiềm năng của các quy trình này trong việc cấu trúc vi các bề mặt cho các ứng dụng nhiệt động lực học.

Coagulation detection is a vital check item for patients undergoing surgery, and those with immunological disease and cardiovascular disease in clinic. Exploring the dynamic detection of the whole coagulation process has long been the research hotspot of experts and scholars. This study had proposed a novel electromagnetic type coagulation detector, which used the round and leaf spring as the middle spring support, with dynamic testing sensor technology of coagulation in vitro as the research objective. The vibration system constituted by support spring and electromagnetic induction device was theoretically analyzed through dynamic modeling of sensor. We conducted modal analysis and harmonic response analysis on the spring support group using finite element method, optimized the analysis results, manufactured the sensor experimental prototype, and constructed the coagulation testing device. We also tested the velocity spectral characteristics and displacement spectral characteristics of the sensor prototype, established the standard curve of POCT (point-of-care testing, POCT) in the rapid detection of coagulation through matching the coagulation testing device with coagulation reagent, and compared its methodology with the imported POCT coagulometer system. Our results suggested that, the vibration velocity of the sensor designed in this study was 1.5 μm/s, and the amplitude was 1.75 × 10−3 μm. The correlation with the imported POCT coagulometer system in terms of test results was as high as 0.996, and the repeatability was 0.002. This study can provide theory and experimental foundation for the electromagnetic vibration induction technology in coagulation detection.

This paper reportsin situ measurement of Young's modulus and residual stress of electroless nickel films through the use of microfabricated nickel test structures, including electrostatic microactuators and passive devices. Th test structures are fabricated in a new surface micromachining process, termed “nickel surface micromachining”, using electroless plated nickel as the structural layer and polysilicon as the sacrificial layer. Subsequent to fabrication, lateral resonant-type electrostatic microactuators of different geometries are resonated by electrical excitation. Using the measured resonant frequencies and knowledge of the device geometry, the Young's modulus of the film is determined. The passive electroless nickel microstructures deform upon completion of the fabrication process due to residual stress in the film. Measurement of this deformation in conjunction with an appropriate mechanical model is used to determine the residual stress in the films.

In this study, a feed-forward backpropagation (FFBP) artificial neural network (ANN) model based on multilayer perceptron (MLP) for computing the pull-in voltage value of fixed–fixed micro-actuators is presented. The proposed ANN model is trained using the numerous pull-in voltage value results of clamped–clamped actuators, which have various physical properties, simulated by a software that employs the finite element method (FEM). As the presented ANN model has been trained for the simulation data, it implicitly takes into account the fringing field, mid-plane stretching and size effects. The accuracy and robustness of the results obtained by the proposed ANN model are verified by comparing with those of the theoretical ones through the simulation and experimental studies previously presented in the literature. The average percentage errors for training and testing data are found to be 0.30 and 0.40 %, respectively, while the maximum percentage error for literature data is calculated as 1.96 %. These results show that the main advantage of the presented ANN model gives satisfying pull-in voltage results over solution space of the simulations with effortless way.

This paper presents the experimental characterization of the creep effect in electrostatically actuated gold microstructures. The tested specimens follow the typical configuration of the microbridge based radio frequency microelectromechanical systems switches and varactors. Initially, the plastic creep strain accumulation with time is measured for the specimens with different geometric dimensions and at different actuation voltages and temperatures. To avoid the size and cumulative heating effects, three specimens with the same geometric dimensions, actuation voltages and constant temperatures are tested. The test results allowed decoupling the permanent plastic strains due to the creep effect and reversible anelastic strains due to the viscoelastic behavior. The pull-in voltage and natural frequency values measured before and after the creep tests are compared, revealing the mechanical stiffness decrease caused by creep.

The ongoing increase of track density requirements of hard disk drives (HDDs) and decrease of flying height of sliders have brought along formidable challenges to suspension design. Conventional design processes are quite tedious and inefficient. This paper presents a HDD suspension design process by using topology optimization. An efficient structural topology optimization method, based on the second derivatives information, is proposed to generate structures which satisfy multiple design objectives including both compliance and eigenfrequencies. This topology optimization approach is successfully applied in the HDD suspension design. The design begins with a very simple initial draft, and the design objectives are defined to minimize the spring rate and maximize the resonant frequencies of first bending, first torsion and sway modes of a suspension. An optimal design concept can be generated from the topology optimization. Then the design is further tuned by using the shape optimization. Finally, an optimal suspension design for femto sliders with much better dynamic characteristics is presented.

A new energy harvesting circuit for battery-less IoT beacon tags is developed herein to maximize power conversion efficiency as well as high throughput power with a wide input–output range. This design energy harvest (EH) circuit incorporates a charge pump (CP) with shoot-through current suppression, a body selector circuit, a maximum power point tracking circuit (MPPT), a timing control circuit, a hysteresis control circuit and a low dropout regulator. Also in this MPPT circuit is a gated clock tuned in a self-adaptive fashion to match the input impedance of the EH circuit to the output impedance of the photovoltaic (PV) panel, thus achieving successfully maximum power point. The circuit is implemented in an integrated chip in an area of 1.2 mm2 via the TSMC 0.18 process. Experiments on the chip are conducted and the results show that the input voltage range is allowed from 0.55 to 1.7 V to effectively harvest the solar power from a flexible dye-sensitized solar cell. The achieved peak power conversion efficiency (PCE) is 77% at the input power of 52 μW. For a wide range of lighting luminance (300–1300 lx,) the achieved average PCE is more than 70%. The achieved wide input–output range and the maximum throughput power of 200 μW is much larger than others reported, while the 77% of PCE is close to that best power conversion efficiency reported.

This work presented the design and test of a double-arm actuated compliant piezoelectric microgripper based on three-stage amplification mechanism, which can also perceive the gripping displacement and force simultaneously. Developing a proper structure for the microgripper to achieve large amplification ratio in a compact space and to ensure sufficient natural frequency is a fundamental and challenging task. Firstly, the structure of piezoelectric microgripper was designed and the kinematic principle of the amplification mechanism was analyzed. Meanwhile, theoretical and simulation analysis of the statics and dynamics were carried out. Then, the calibration methods for both force and displacement sensors are presented. The calibration coefficients are 0.163 $$\text {mN/mV}$$ and 0.040 $$\mu \!\!\text { m/mV}$$ , respectively. Finally, a series of experiments were performed to verify the performance of the designed microgripper. The test results show that the displacement amplification ratio of the microgripper is 16.8, and the maximum output displacement of 102.30 $$\mu \!\!\text { m}$$ and the maximum gripping force of 227.70 $$\text {mN}$$ can be reached when applying a sinusoidal input voltage with the frequency of 0.10 Hz and the amplitude of 100 $$\text {V}$$ . The closed-loop experiment shows that the peak-to-valley errors of both gripping displacement and force are less than 0.49 $$\mu \!\!\text { m}$$ and 3.74 $$\text {mN}$$ respectively. The obtained natural frequency of 215.1 Hz. The micro-gripper achieves excellent static and dynamic performance in clamping accuracy, natural frequency, clamping range, and dual finger independence.