Micromechanical Sensors Research Articles

1D Topological Interface States for Improving Optical Sensors

AbstractThe field of compact optical microcavities has received significant research in the past decades, and a broad range of cavity‐based micromechanical sensors has been demonstrated. The present approach replaces the frequently employed, complex etched cantilever and membrane structures with a simple thin‐film system based on a compressible photonic microcavity to achieve pressure‐sensitive wavelength shifting of resonant modes. The effects of a topological dielectric mirror architecture on the light propagation in the system are extensively investigated. Topologically improved light‐matter interaction is experimentally demonstrated for systems where thin‐film devices are mounted on one side of the photonic cavity due to mechanical constraints. Coupled topological states are examined under the aspect of mode splitting and exhibit advantageous splitting tunability compared to non‐topological systems. The findings are complemented by the proposal of a simple spectral evaluation method allowing significant improvement in the precision of integrated Fabry‐Pérot sensors. The readout concept of the presented sensor allows a scalable improvement of the measurement precision by evaluating the resonant‐mode order in the deformable cavity. The experimental results and conceptual advancements provide pathways for significant improvements addressing the efficiency of light‐matter interaction in Fabry‐Pérot cavities and the readout precision of sensors incorporating thin‐film photodiodes in multimode photonic cavities.

Synthesis of a measurement procedure for estimating the orientation of a small unmanned aerial vehicle under conditions of changing status of measurement results

The problem of processing measurement information with changing status of measurement results of micromechanical sensors of an intelligent on-board measuring system of a small unmanned aerial vehicle is considered. While vehicle is in the air, the measurement results status changes from confirmed to orienting, for example, due to sensor defects, degradation of the measuring channel, the appearance of false measurement output signals of micromechanical sensors due to vibrations and shocks caused by the movement of air masses. As a result, the probability of stability loss of a small unmanned aerial vehicle increases and it is necessary to raise the accuracy of estimating its orientation in conditions of changing status of measurement results. The measuring procedure of the Kalman structure is considered, the equations of which are determined with accuracy to the parameters of the transition and noise matrices of the state, as well as the perturbation vector, characterizing the measuring process. The parameter values are determined by a mathematical model for converting measuring information based on a dynamic mathematical model, which distinguishes the developed measuring procedure from a measuring procedure with a classical transition matrix. A neural network is used to find unknown parameters. A multilayer perceptron was selected as the basis of a neural network, for which an error back propagation algorithm is used to train. Based on the results of mathematical modeling and measurement experiment, it was found that the accuracy of the synthesized measuring procedure based on a dynamic mathematical model is higher than the accuracy of the measuring procedure of the Kalman structure with a classical transition matrix. The results of the study will be useful in the development of intelligent measurement procedures for on-board measurement systems operating under conditions of changing status of measurement results

Near Infrared -Visible Photonic Bandgap in One-Dimensional Periodic Photonic Crystal Structure Composed of Tio2/Te Layers

In this present paper, we consider some features of the states of one-dimensional photonic crystals. Form the numerical results performed by transfer matrix method in periodic multilayer structure made of titanium dioxide and tellurium material, it is found that the structure possesses a photonic band gap it was determined that the structure has a photonic band gap in the borderline visible and infrared spectral region. Our predictions were in good agreement with the photonic bandgap tuning. Our simple model can also predict and explain the effect of incidence angle and wavelength and number of layers on the photonic bandgap. We expect such structures to play an important role in micromechanical tunable optical sensors and filters.

MOTION CAPTURE WITH MEMS SENSORS

The object of this article is the registration and analysis of human movements based on sensors. This paper presents a comparison of the basic methods of data processing from inertial micromechanical sensors to collect data a device was implemented that captures movements. As result the device uses the motion data from accelerometer and gyroscope to calculate the motion trajectory: the angle of rotation and acceleration. The data is read by the microcontroller, after which it is filtered and processed by one of the filters (Complementary, Kalman), and finally transferred to a computer for further analysis and display. The purpose of the article is to compare several methods of data processing from microelectromechanical. The results obtained: device was developed, obtained data that can be used to characterize the methods and analyze their work in the system. Conclusions: In the course of the study, a device was developed for collecting and processing data from MEMS sensors, which showed the effectiveness of the complementary filter in comparison with the Kalman filter in real-time systems with limited computing power. Real results confirmed that the results of the complementary method using less computational resources are not far behind the more costly Kalman filter without the use of auxiliary sensors, like a digital compass.

A sigma-delta interface built-in self-test and calibration for microelectromechanical system accelerometer's utilizing interpolation method

This work presents the capacitive micromechanical accelerometer with a completely differential high-order switched capacitor sigma-delta modulator interface. Such modulation interface circuit generates one-bit output data using a third sigma-delta modulator low-noise front-end, doing away with the requirement for a second enhanced converter of resolution to encode the feedback route analog signal. A capacitive micromechanical sensor unit with just a greater quality factor has been specifically employed to give greater resolution. The closed-loop and electrical correction control are used to dampen the high-Q values to get the system's stability with high-order. This microelectromechanical system (MEMS) capacitive accelerometer was calibrated using a lookup table and Akima interpolation to find manufacturing flaws by recalculating voltage levels for the test electrodes. To determine the proper electrode voltages for fault compensation, COMSOL software simulates a number of defects upon that spring as well as the fingers of the sensor system. When it comes time for the feedback phase of a proof mass displacement correction, these values are subsequently placed in the lookup table.

Research on personalized recommendation algorithm for micromechanical sensors based on cloud model

Abstract In order to improve the ability of micromechanical sensors to update data-matching nodes in real-time and speed up the establishment of a neighbor relationship between nodes, this paper proposes a personalized recommendation algorithm for micromechanical sensors based on the cloud model to improve the stability and real-time performance of micromechanical sensors. The algorithm uses the service attribute values of the cloud computing model and cloud clustering method to set feature term labels and establish a cloud service similarity matrix so as to meet the user-matched manufacturing service requirements. The intra-class clustering technique is applied to measure the clustering effect, and the evaluation function of each clustering number is calculated on the basis of considering the time sequence to determine the best clustering result to complete the personalized recommendation path for micromechanical sensors. To verify the application effect of the personalized recommendation algorithm for micromechanical sensors based on the cloud model, experiments are conducted. The results show that the recommendation algorithm in this paper can always control the node energy consumption below 2.5×103, and the average discovery delay is stable between 41-43 seconds. And the sensor response time is 12.1 seconds, and the average absolute deviation value is 0.23, which is nearly 1.3 times smaller than 0.53 and 0.52 of the collaborative recommendation algorithm and hybrid recommendation algorithm. It can be seen that the recommendation algorithm in this paper solves the problem of excessive neighbor discovery delay in the communication process of micromechanical sensors and effectively improves the personalized recommendation performance of micromechanical sensors.

Analytical and Experimental Investigation of the Rotary Inertia Effects of Unequal End Masses on Transverse Vibration of Beams

In this study, the transverse vibration of free–free slender beams with two unequal end masses attached were studied. The effects of the rotary inertia of the end masses on the free vibration of the beam were investigated. An exact frequency equation and the boundary conditions were obtained by using the Euler–Bernoulli beam theory and Hamilton’s principle. Natural frequencies and mode shapes of the beams in transverse vibrations were calculated for various combinations of physical and geometrical parameters, such as mass ratios, the distances between the attachment point and the center of the masses, etc. The effects of an increase in the rotational inertia of the end masses and different mass ratios on the natural frequencies and mode shapes of the beam are presented. It is shown that the increase in the rotational inertia of the end masses had a greater effect at low frequencies of the beam. In addition, experimental tests were performed to validate the obtained analytical results. A good agreement was obtained between the analytical and experimental results. The main scope of this study was to reveal the effects of the rotary inertia of the end masses on the dynamic behavior of the beam. Thus, the aim is to contribute to the understanding of the properties of the end mass and the effect of rotary inertia on the dynamics of end-mass-attached structures. Furthermore, the results obtained from this research are helpful for designing end-mass-attached structures, such as micromechanical sensors, energy harvesters, and Stockbridge-type dynamic absorbers.

Beyond biology: alternative uses of cantilever-based technologies.

Micromechanical cantilever sensors are attracting a lot of attention because of the need for characterizing, detecting, and monitoring chemical and physical properties, as well as compounds at the nanoscale. The fields of application of micro-cantilever sensors span from biological and point-of-care, to military or industrial sectors. The purpose of this work focuses on thermal and mechanical characterization, environmental monitoring, and chemical detection, in order to provide a technical review of the most recent technical advances and applications, as well as the future prospective of micro-cantilever sensor research.

Development and Research of a Micromechanical Rotation Sensor

The description of the developed design of the sensitive element of the micromechanical rotation sensor is given, the simulation results are presented. The results of experimental studies are presented, showing the efficiency of the developed design. As a result of the study of the Bosch process using methods for planning multifactor experiments, the modes of deep etching of silicon were optimized. Prototypes of sensitive element MEMS accelerometers have been produced.

Detection of Volatile Alcohol Vapors Using PMMA-Coated Micromechanical Sensors: Experimental and Quantum Chemical DFT Analysis

Micromechanical sensors, in which the sensor response is created as a result of molecular interactions on the sensors’ surfaces, have been employed as a powerful technique for rapid and sensitive detection of low concentrations of chemical and biological materials. In the study reported herein, poly(methyl methacrylate) (PMMA)-coated microcantilever (MCL) sensors were used to detect the vapors of volatile alcohols (methanol, ethanol, and isopropanol) at three different concentrations. A vapor generator was used to generate and flow the alcohol vapor onto the PMMA coated MCL surface in a closed system chamber. The vapor adsorption onto the MCL surface results in a rapid and measurable deflection of the MCL. No significant deflections of the uncoated MCL occurred when the different vapors were passed through into the microcantilever chamber. Linear concentration–deflection responses were observed, with the highest sensitivity shown with methanol, followed by ethanol and then isopropanol. Density functional theory (DFT) quantum chemical calculations were conducted to estimate the electronic interaction energies (ΔIE) between the alcohol molecules and MMA and two different model tetrameric segments of PMMA. The computed ΔIEs were in the same order as the experimentally observed order: methanol > ethanol > isopropanol.

Coupled Double Closed-Loop Control for an MEMS Resonant Accelerometer.

There is mutual coupling between amplitude control and frequency tracking control in the closed-loop control of micromechanical resonant sensors, which restricts sensor performance. This paper introduces the principle of an in-plane vibration micromechanical resonant accelerometer with electrostatic stiffness. The characteristic parameters of the microaccelerometer were obtained through computer-aided dimension measurement and an open-loop frequency sweep test of the fabricated microstructure. An accurate numerical model was established based on the accelerometer’s dynamic principle and characteristic parameters. We established the double closed-loop driving analysis model of amplitude automatic gain control and resonant frequency phase-locked tracking. We used the averaging method to analyze the steady-state equilibrium point and the stable condition. We concluded that the integral coefficient can improve the startup overshoot when the amplitude automatic gain control loop satisfies the stability condition. Under the constraint of frequency tracking, the sizeable coefficient of the integrator can improve the system instability of the amplitude control loop. The theoretical analysis and simulation were helpful in the design and debugging of the system circuit.

A passive acceleration sensor with mechanical 6 bit memory and mechanical analog-to-digital converter

This paper presents the design, modeling, fabrication and characterization of a passive micromechanical acceleration sensor intended for condition monitoring. The sensor is composed of purely micromechanical components forming a mechanical integrated sensing circuit, which allows to measure, select, store, and digitize the peak value of an imposed acceleration without the need of electrical auxiliary energy. We present micromechanical components arranged in a mechanical integrated sensor circuit. A network model is derived describing the static mechanical properties of the system. As part of the accelerometer, a cascaded mechanical memory is presented in detail which allows to store an acceleration peak value with a resolution of 6 bits, i.e. 64 discrete states. The memory is resettable by an electrostatic actuator. For an electrical read out of the memory, e.g. by RFID, an integrated micromechanical analog-to-digital converter is used.

Experimental strapdown inertial navigation system for the autonomous guidance system of a short-range uav

The task of experimental verification of the possibility of using a miniature strapdown inertial navigation system (SINS) on micromechanical sensors for autonomous guidance of a short-range manned aircraft moving along a programmed hypothetical trajectory is considered.
 A mathematical model of the first approximation of the instrumental errors of the two-coordinate autonomous SINS of the aircraft with a short flight time was obtained. The mathematical model allows both to calculate the values of these errors for specific types of inertial sensors used in SINS (direct analysis problem), and to choose the types of accelerometers and gyroscopes based on ensuring the given accuracy of SINS (inverse synthesis problem). The requirements for permissible errors of accelerometers and gyroscopes of the SINS sensor unit have been determined.
 The design and manufacturing technology of an experimental SINS based on a triaxial micromechanical accelerometer and three uniaxial micromechanical gyroscopes are described.
 The technology of flight tests of the experimental SINS is considered. The test results of the experimental SINS of the aircraft, created in accordance with the requirements specified in the article, confirmed the correctness of the chosen approach to ensuring the accuracy of the SINS for the autonomous inertial guidance system of short-range aircraft.

Thickness dependence of the response of metal-dioxide-based micromechanical sensors for sensitive gamma-ray detection

In this study, we investigated the effect of the thickness of metal-dioxide thin films on silicon (Si) micro-electromechanical systems (MEMS) for sensitive, accurate, and reproducible detection of gamma-radiation dose. Silicon wafers and microcantilevers were coated with various thicknesses of titanium dioxide (TiO2) thin films and controlled by the number of cycles in atomic layer deposition (ALD) under 17-mbar pressure and temperature of 200 °C. All samples were exposed to different doses of gamma (0, 10, and 20 kGy) using a60Co source. Before and after gamma irradiation, the optical and mechanical properties of the TiO2 thin films on Si wafers were studied by spectroscopic ellipsometry (SE) and atomic force microscopy (AFM). The resonance frequency shift (RFS) resulting from exposing different thicknesses of TiO2 thin films on MEMS-based cantilevers to gamma-radiation doses were evaluated by AFM. SE results revealed the film thicknesses of 11.91, 21.77, 62.91, and 218.23 nm at 250, 500, 1250, and 2500 coating cycles, respectively. Through SE, other optical constants, such as surface roughness (SR) and refractive index (n), were obtained. The root-mean-square (RMS) SR obtained from AFM images and SE measurements on Si wafers showed the same behavior under gamma radiation according to the TiO2 thin-films thicknesses. The RFS results show that the best film thickness for reproducible and sensitive gamma-radiation detection was 218.23 nm. The frequency shift as the gamma dose increase from 0 to 20 kGy was ∼60 Hz. It is a very palpable and linear shift; hence, it can be used as a dosimeter sensor. The results were verified by the statistical correlation coefficient method to find the correlation between RFS and the gamma dose at different film thicknesses. Correlation results are consistent with other results.

Micromechanical mode-localized electric current sensor

This paper outlines the design of a novel mode-localized electric current sensor based on a mechanically sensitive element of weakly coupled resonator systems. With the advantage of a high voltage sensitivity of weakly coupled resonator systems, the current under test is converted to voltage via a silicon shunt resistor, which causes stiffness perturbation to one resonator. The mode-localization phenomenon alters the energy distribution in the weakly coupled resonator system. A theoretical model of current sensing is established, and the performance of the current sensor is determined: the sensitivity of the electric current sensor is 567/A, the noise floor is 69.3 nA/√Hz, the resolution is 183.6 nA, and the bias instability is 81.6 nA. The mode-localized electric current sensor provides a new approach for measuring sub-microampere currents for applications in nuclear physics, including for photocurrent signals and transistor leakage currents. It could also become a key component of a portable mode-localized multimeter when combined with a mode-localized voltmeter. In addition, it has the potential for use in studying sensor arrays to achieve higher resolution.

Amplifying charge-sensing in micromechanical oscillators based on synchronization

Resonant micromechanical charge sensor is widely studied, however, the performance is suffocated by nonlinearity. Here, a sensing enhancement technique based on synchronization is proposed. Charge-sensing amplified by synchronization induced frequency locking of a ratio 9 in a couple of micromechanical oscillators separated over 1 m is demonstrated. One axial strain modulated DETF is working on its flexural mode to detect the electric charge. The sensing output oscillation frequency is injected into a high Q micro-machined disk oscillator via a coaxial cable to form synchronization. We show that the sensitivity of the disk oscillator outputs is improved up to 9 folds due to the frequency locking effect. Also, the equivalent detection frequency stability can be enhanced to 3 folds. The perturbation synchronizing signal can be transmitted over a long distance and may lead to applications for enhancing sensor performance.

Micromechanical resonant cantilever sensors actuated by fringing electrostatic fields

We report on the architecture and operational principle of a resonant cantilever-type displacement sensor. The device is actuated electrostatically by a side electrode that is coplanar with the cantilever and by a gap-closing electrode positioned underneath the beam. The unique electrode geometry combined with the appropriate actuating voltages allows positioning of the cantilever in close proximity to the bistability threshold, where the frequency sensitivity to the electrode displacement is enhanced. Using a reduced order model backed by numerical simulations, the dependencies of the device frequency on the beam’s deflections and the actuation voltages were mapped. We show wide-range tunability that spans a range between softening and hardening behavior. We demonstrate displacement sensing using fabricated single crystal silicon ≈2000 µm long, ≈5 µm thick cantilevers. When compared to a resonant cantilever sensor actuated solely by a gap-closing electrode, measurements from our fringing field actuated devices show a four times higher sensitivity of ≈98 Hz µm−1. The suggested approach may find applications in a broad range of micro and potentially nano-scale applications including resonant inertial, force, mass and bio-sensors.

Разработка математической модели микромеханического датчика инерциальной информации

Creating an integrated system of orientation and navigation of small spacecraft based on precision sensors of inertial and external information is an urgent task for the space industry. The object of research is a micromechanical gyroscope (MMG) with a gimbal suspension of a sensitive element. The problem of increasing the accuracy of the MMG by building a new mathematical model of the sensor accurate enough to take into account the influence of technological errors of manufacturing and nonlinear nonstationary effects associated with finite oscillations of a sensitive element and slow change in system parameters. To build a digital model of the micromechanical inertial information sensor, parametric design systems have been applied enabling a full cycle of design documentation creation and calculations. The parametric calculations of the structural scheme were used to analyze the stress-strain state of mechanical elements under various external influences including extreme overloads. The obtained mathematical model was supplemented by analytical methods of nonlinear mechanics, which allow taking into account the influence of finite vibrations of structural elements on the dynamics and accuracy of measurements of angular motion of the gyroscope base. The results of bench experimental tests of sensors carried out to check the adequacy of the developed numerical mathematical model are discussed.

Design of the Capacitive Dual-Mass Micromechanical Gyroscope

Development of micromechanical inertial sensors have made it possible to use them in the navigation and motion control systems. This application area imposes strict requirements on sensors. One of the ways to meet the requirements and to improve the gyroscope characteristics is to apply a dual- or multi-mass architecture of a gyroscope sensing element. This paper presents the results of dual-mass micromechanical gyroscope with a measurement range of ±450°/s design. The complex design method, including simulation at the system level, model refinement based on the results of finite element modelling, and modelling of individual electronic blocks at the circuit level, is described.

(Invited) Metal Oxide Based Micromechanical Sensors for Sensitive Gamma Rays Detection

In this talk, I will present our ongoing efforts on developing sensitive gamma rays dosimeter using two sensing techniques namely, metal oxide-coated microcantilever and Quartz tuning forks. The primary objective of these studies is to exploit the appealing characteristics (i.e. low in cost, sensitive and rapid) of the abovementioned techniques in developing gamma radiation dosimeters. In this first study, we have investigated the potential of exploiting TiO2 thin films as a sensing layer on Silicon microcantilevers for detection of gamma-ray radiations. Silicon microcantilever and wafers are both used for this purpose. All samples were exposed to gamma rays produced by 60Co with different doses ranging between 0 kGy and 40 kGy. The optical properties of silicon-coated by TiO2 at 200°C ALD grown and 100 nm thickness were studied before and after irradiation using X-ray diffraction (XRD) spectrum, scanning electron microscopy (SEM) and spectroscopic ellipsometry (SE) and Atomic force microscopy (AFM). The optical studies by X-ray diffraction showed that change of our film from the nanocrystalline mixture of rutile and anatase phases to anatase by irradiation, this change appeared as (Δf) in AFM whereas the response of sensors to the doses between 0KGy and 20KGy was very sensitive and linear. The results of the spectroscopic ellipsometry measurements showed the same linearity change in the thickness, roughness and optical constants with irradiation doses were fitted using the Cauchy model. In the second study, gold coated quartz tuning forks were exposed to gamma radiations and we found that QTFs underwent a clear change in response to increasing gamma dosage. Our results show that both techniques are excellent candidates for dosimetry applications.