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A novel dual-drive MEMS device integrated with both a thermal actuator and an electrostatic actuator is proposed and fabricated, which realizes the convenient in-situ electro-mechanical test for nanomaterials. The drive mode can be agilely selected to analyze different mechanical properties and the accuracy of the test can be verified by self-contrast of the two driving modes. Using the nanomanipulator as the transfer method, coupled mechanical and electrical tests are carried out for TiO 2 nanowires. The measured Young's modulus of the nanowire in the two driving modes are 78.2 GPa and 85.6 GPa, and the fracture stress are 562 MPa and 584 MPa, respectively. The electron beam (e-beam) irradiation effect on electrical properties is investigated. Meanwhile, the resistance of the nanowires is determined as a variable of strain, which demonstrates the changes in resistance are the result of the loaded strains. The resistance decreases slightly after 2000 cycles of tensile, which is believed to be a delayed response brought about by electron beam irradiation. The experiment results indicate that the proposed MEMS device will facilitate the in-situ test of 1D/2D nanomaterials. [Display omitted] • A novel dual-drive MEMS device integrated both a thermal actuator and an electrostatic actuator was reported. • The drive mode can be conveniently selected. • The accuracy of the test can be verified by the two driving modes. • The coupled mechanical and electrical tests can be carried out. [ABSTRACT FROM AUTHOR]

Abstract: An electrostatic pull-in beam has been widely used to measure material properties. There has been an increasing need for MEMS devices with composite films in recent years. This paper presents an approach to characterize the material properties of the composite films using the electrostatic pull-in test structure which is composed of the composite fixed-fixed beam. An analytical model for the pull-in voltage of the composite doubly-clamped beam is presented, which takes into account the influence of lateral residual stress along width direction of the composite beam. Based on this improved model, a test structure is designed to avoid the influence of lateral residual stress along the width of the composite beam. An in situ method for simultaneously extracting material properties (Young''s modulus and residual stress) of each layer for the composite films is reported. And doubly-clamped surface micromachined beams with multi-cup style anchors were fabricated to support the model of pull-in voltage. The validation and accuracy of the extracting method have been confirmed by FEM simulation and experiments. [Copyright &y& Elsevier]

Abstract: Wafer level thin film residual stress is generally determined by a full-field optical method, which converts the measured curvatures into the stress using Stoney formula. During the fabrication of the IC and MEMS devices, however, multilayered thin films are often generated on both sides of the wafer simultaneously. By extending the Stoney formula, this paper presents a method for measuring residual stress in the multilayered films on the wafer. In the method, only the back film layers of the wafer need to be etched in turn and corresponding curvature radii is measured by the full-field optical method. The residual stress of each film layer may then be obtained by the radii using the extended Stoney formula. By comparing the proposed method with the existing method using the traditional Stoney formula, it is shown that the proposed method is more simple and economical for practical applications. The extended Stoney formula was verified by Coventorware. Experiments show that the proposed method is simple and accurate for process monitoring. [Copyright &y& Elsevier]

• In this manuscript, we have reported a convenient and cost-effective method to fabricate a strain sensor based on double-layer micro-structures with MWCNTs and Ecoflex (DMME), which possesses high sensitivity and wide linear workable range due to a synergetic effect of the double-conductive layer structures. The obtained stain sensor exhibits outstanding high gauge factors (GF = 29.4), relatively short response time (<200 ms), and excellent cycling stability over 5000 cycles. Moreover, based on the above excellent sensing performance, the DMME strain sensor is ideally qualified for human activity detection, medical monitoring, artificial intelligence devices, and other sensitive information collection. The increasing demand for wearable electronic devices is promoting the development of highly elastic strain sensors, which can monitor various physical parameters and essential factors for realizing next generation electronics. However, it is still challenging to simultaneously achieve wearable strain sensors with sufficient sensitivity within wide stretching sensing ranges under mechanical stimuli in view of their widespread applications, including electronic skin, smart textiles, as well as healthcare monitoring. Herein, we propose a simple, cost-effective strain sensor based on synergetic conductive networks constituted by double-layer microstructures with multi-walled carbon nanotubes and elastomer. The micro-spinous structures of MWCNTs and the peak-valley microstructures have extended stretching sensing ranges with high sensitivities. The double-layer strain sensor exhibits high gauge factors (GF = 12.3 and 29.4) in the two linear stretching strain ranges (0–50 % and 50–200 %) with a long-term reusability, low-hysteresis, and fast response under dynamic loading. This sensor demonstrates excellent mechanical performance in real-time human motion detecting and distinguishing subtle signals, such as vocalization, muscle motions, as well as fingers or wrists. [ABSTRACT FROM AUTHOR]

This paper develops an analytical model for the deflection of clamped–clamped multilayer beams as a function of applied voltage by the energy method. The normalized displacement of the center of the beams and the pull-in voltage have been obtained, the model is also suitable to clamped–clamped beams with compressive stress. The model results are compared with FEM simulations, provided by the CosolveEM module in Coventorware, showing excellent agreement. This provides an approach of extracting material properties for the multilayer beams. [Copyright &y& Elsevier]