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We present a novel electric permittivity sensor based on Bleustein–Gulyaev (BG) waves. Toward that end, we formulate the nonlinear electromechanical partial differential equations governing a BG wave resonator. We find that the permittivity of the material-under-test changes the sensor natural frequencies, thereby enabling the implementation of a frequency-shift permittivity sensor. We also find that the sensor sensitivity is enhanced by increasing bias voltage to drive the sensor into the nonlinear regime. Bias was found to be limited by electrical breakdown. The sensor was fabricated by depositing aluminum electrodes on a shear-poled lead zirconate titanate piezoelectric substrate. Experimental measurements of the displacement on the sensor surface were in good agreement with the developed model. [ABSTRACT FROM AUTHOR]

This paper offers a critical overview of recent advancements in aqueous sensors for heavy metals. The paper focuses on the challenges and advantages of using microelectromechanical systems (MEMS) sensors in aqueous environments, as well as technical considerations for choosing appropriate polymeric sensing materials. In addition, general considerations and recommendations are included for developing MEMS chemical sensors. These considerations centre around the chemical nature of the target analyte and the environment of the sensor application. By following these recommendations and taking the time to design a suitable sensor and sensing material for the target application instead of a trial‐and‐error approach, it is possible to save both time and cost. [ABSTRACT FROM AUTHOR]

We present an analytical approach and a reduced-order model (macromodel) to investigate the behavior of electrically actuated microbeam-based MEMS. The macromodel provides an effective and accurate design tool for this class of MEMS devices. The macromodel is obtained by discretizing the distributed-parameter system using a Galerkin procedure into a finite-degree-of-freedom system consisting of ordinary-differential equations in time. The macromodel accounts for moderately large deflections, dynamic loads, and the coupling between the mechanical and electrical forces. It accounts for linear and nonlinear elastic restoring forces and the nonlinear electric forces generated by the capacitors. A new technique is developed to represent the electric force in the equations of motion. The new approach allows the use of few linear-undamped mode shapes of a microbeam in its straight position as basis functions in a Galerkin procedure. The macromodel is validated by comparing its results with experimental results and finite-element solutions available in the literature. Our approach shows attractive features compared to finite-element softwares used in the literature. It is robust over the whole device operation range up to the instability limit of the device (i.e., pull-in). Moreover, it has low computational cost and allows for an easier understanding of the influence of the various design parameters. As a result, it can be of significant benefit to the development of MEMS design software. [883] Index Terms--Capacitive microswitches, microelectromechanical systems (MEMS), pressure sensors, pull-in time, reduced-order models.

Summary: Due to physically demanding tasks in construction, workers are exposed to significant safety and health risks. Measuring and evaluating body kinematics while performing tasks helps to identify the fundamental causes of excessive physical demands, enabling practitioners to implement appropriate interventions to reduce them. Recently, non-invasive or minimally invasive motion capture approaches such as vision-based motion capture systems and angular measurement sensors have emerged, which can be used for in-field kinematics measurements, minimally interfering with on-going work. Given that these approaches have pros and cons for kinematic measurement due to adopted sensors and algorithms, an in-depth understanding of the performance of each approach will support better decisions for their adoption in construction. With this background, the authors evaluate the performance of vision-based (RGB-D sensor-, stereovision camera-, and multiple camera-based) and an angular measurement sensor-based (i.e., an optical encoder) approach to measure body angles through experimental testing. Specifically, measured body angles from these approaches were compared with the ones obtained from a marker-based motion capture system that has less than 0.1 mm of errors. The results showed that vision-based approaches have about 5–10 degrees of error in body angles, while an angular measurement sensor-based approach measured body angles with about 3 degrees of error during diverse tasks. The results indicate that, in general, these approaches can be applicable for diverse ergonomic methods to identify potential safety and health risks, such as rough postural assessment, time and motion study or trajectory analysis where some errors in motion data would not significantly sacrifice their reliability. Combined with relatively accurate angular measurement sensors, vision-based motion capture approaches also have great potential to enable us to perform in-depth physical demand analysis such as biomechanical analysis that requires full-body motion data, even though further improvement of accuracy is necessary. Additionally, understanding of body kinematics of workers would enable ergonomic mechanical design for automated machines and assistive robots that helps to reduce physical demands while supporting workers' capabilities. [ABSTRACT FROM AUTHOR]

We experimentally investigate the primary superharmonic of order two and subharmonic of order one-half resonances of an electrostatic MEMS actuator under direct excitation. We identify the parameters of a one degree of freedom (1-DOF) generalized Duffing oscillator model representing it. The experiments were conducted in soft vacuum to reduce squeeze-film damping, and the actuator response was measured optically using a laser vibrometer. The predictions of the identified model were found to be in close agreement with the experimental results. We also identified the noise spectral density of process (actuation voltage) and measurement noise. [ABSTRACT FROM AUTHOR]

This paper demonstrates and compares different experimental techniques utilized to estimate the quality factor (Q) and natural frequency from non-contact measurements of Microelectromechanical Systems (MEMS) motions. The relative merits of those techniques are contrasted in Q factor estimation for a cantilever beam MEMS actuator, operated in three configurations: free standing, arc-shaped, and s-shaped. It is found that damping estimation techniques that seek to minimize the deviation between the response of an "assumed" linear oscillator and the measured time-history of the motions are superior to those traditional techniques, such as logarithmic decrement and half-power bandwidth. Further, it is found that Q increases three-fold as the actuator contact with the substrate evolves from a line to an area. [ABSTRACT FROM AUTHOR]