MEMS Technology Research Articles

Silicon 3D Microdosimeters for Advanced Quality Assurance in Particle Therapy

The Centre for Medical Radiation Physics introduced the concept of Silicon On Insulator (SOI) microdosimeters with 3-Dimensional (3D) cylindrical sensitive volumes (SVs) mimicking the dimensions of cells in an array. Several designs of high-definition 3D SVs fabricated using 3D MEMS technology were implemented. 3D SVs were fabricated in different sizes and configurations with diameters between 18 and 30 µm, thicknesses of 2–50 µm and at a pitch of 50 µm in matrices with volumes of 20 × 20 and 50 × 50. SVs were segmented into sub-arrays to reduce capacitance and avoid pile up in high-dose rate pencil beam scanning applications. Detailed TCAD simulations and charge collection studies in individual SVs have been performed. The microdosimetry probe (MicroPlus) is composed of the silicon microdosimeter and low-noise front–end readout electronics housed in a PMMA waterproof sheath that allows measurements of lineal energies as low as 0.4 keV/µm in water or PMMA. Microdosimetric quantities measured with SOI microdosimeters and the MicroPlus probe were used to evaluate the relative biological effectiveness (RBE) of heavy ions and protons delivered by pencil-beam scanning and passive scattering systems in different particle therapy centres. The 3D detectors and MicroPlus probe developed for microdosimetry have the potential to provide confidence in the delivery of RBE optimized particle therapy when introduced into routine clinical practice.

Advanced e-Call Support Based on Non-Intrusive Driver Condition Monitoring for Connected and Autonomous Vehicles.

Background: The growth of the number of vehicles in traffic has led to an exponential increase in the number of road accidents with many negative consequences, such as loss of lives and pollution. Methods: This article focuses on using a new technology in automotive electronics by equipping a semi-autonomous vehicle with a complex sensor structure that is able to provide centralized information regarding the physiological signals (Electro encephalogram—EEG, electrocardiogram—ECG) of the driver/passengers and their location along with indoor temperature changes, employing the Internet of Things (IoT) technology. Thus, transforming the vehicle into a mobile sensor connected to the internet will help highlight and create a new perspective on the cognitive and physiological conditions of passengers, which is useful for specific applications, such as health management and a more effective intervention in case of road accidents. These sensor structures mounted in vehicles will allow for a higher detection rate of potential dangers in real time. The approach uses detection, recording, and transmission of relevant health information in the event of an incident as support for e-Call or other emergency services, including telemedicine. Results: The novelty of the research is based on the design of specialized non-invasive sensors for the acquisition of EEG and ECG signals installed in the headrest and backrest of car seats, on the algorithms used for data analysis and fusion, but also on the implementation of an IoT temperature measurement system in several points that simultaneously uses sensors based on MEMS technology. The solution can also be integrated with an e-Call system for telemedicine emergency assistance. Conclusion: The research presents both positive and negative results of field experiments, with possible further developments. In this context, the solution has been developed based on state-of-the-art technical devices, methods, and technologies for monitoring vital functions of the driver/passengers (degree of fatigue, cognitive state, heart rate, blood pressure). The purpose is to reduce the risk of accidents for semi-autonomous vehicles and to also monitor the condition of passengers in the case of autonomous vehicles for providing first aid in a timely manner. Reported abnormal values of vital parameters (critical situations) will allow interveneing in a timely manner, saving the patient’s life, with the support of the e-Call system.

Reliable Data Acquisition System for a Low-Cost Accelerograph Applied to Structural Health Monitoring

This paper presents and evaluates a continuous recording system designed for a low-cost seismic station. The architecture has three main blocks. An accelerometer sensor based on MEMS technology (Microelectromechanical Systems), an SBC platform (Single Board Computer) with embedded Linux and a microcontroller device. In particular, the microcontroller represents the central component which operates as an intermediate agent to manage the communication between the accelerometer and the SBC block. This strategy allows the system for data acquisition in real time. On the other hand, the SBC platform is used for storing and processing data as well as in order to configure the remote communication with the station. This proposal is intended as a robust solution for structural health monitoring (i.e. in order to characterize the response of an infrastructure before, during and after a seismic event). The paper details the communication scheme between the system components, which has been minutely designed to ensure the samples are collected without information loss. Furthermore, for the experimental evaluation the station was located in the facilities on a relevant infrastructure, specifically a hydroelectric dam. The system operation was compared and verified with respect to a certified accelerograph station. Results prove that the continuous recording system operates successfully and allows for detecting seismic events according to requirements of structural health applications (i.e. detects events with a frequency of vibration less than 100 Hz). Specifically, through the system implemented it was possible to characterize the effect of a seismic event of 4 MD reported by the regional seismology network and with epicenter located about 30 Km of the hydroelectric dam. Particularly, the vibration frequencies detected on the infrastructure are in the range of 13 Hz and 29 Hz. Regarding the station performance, results from experiments reveals an average CPU load of 51%, consequently the processes configured on the SBC platform do not involve an overload. Finally, the average energy consumption of the station is close to 2.4 W, therefore autonomy provided by the backup system is aroud of 10 hours.

Research on Internet of Things Technology for Intelligent Three-Dimensional Online Monitoring System of Marine Ranch

The online monitoring network of marine ranching ecological environment is one of the important development directions of marine ranching construction. Traditional marine monitoring systems are large in size, high in power consumption, and expensive. The investment in pasture construction cannot achieve a large amount of investment to form a monitoring network. There is an urgent need for a low-cost marine monitoring method that can afford a large area and high spatial density. This problem cannot be realized in traditional technology. Based on MEMS technology, this paper develops low-cost monitoring small floats that can be deployed in a large number of “swarm bees”, with high spatial and temporal resolution, and take into account environmental and biological population characteristics monitoring. Each small float is connected to a multi-node sensor chain and video monitoring node. The low-cost surface and underwater wireless transmission and wireless communication means are used for networking observation, which proposes a brand-new solution for the construction of the intelligent three-dimensional monitoring of the marine pasture environment.

Retraction Note: Structure of plain granular rock mass based on motion sensor and movement evaluation of dancers

Human motion sensor is one of the most important devices for motion detection. In recent years, it has attracted the attention of many experts and researchers. According to the system, this paper compares the output of the arbitrary rotation of the human motion sensor, the position of the singular point, and the change of the magnetic field, and displays the calculation results, which verifies the accuracy of the output of the position calculation algorithm. With the development of MEMS technology, the advantages of human motion sensors brought by MEMS devices become more and more obvious. Dance cheerleading has developed rapidly in recent years and has spread all over the world. With the continuous improvement of the level of dance cheerleading competition, China’s physical requirements for cheerleading athletes are also constantly improving, and the athletes’ sports quality can be called the soul of dance cheerleading. In this paper, the relationship between structural simulation parameters and macro parameters of granular rock mass in plain area is studied. Through the numerical modeling of macro response of various models, the influence of contact stiffness, adhesion strength, friction coefficient, void coefficient, stiffness coefficient, and viscosity coefficient is analyzed, and the contact stiffness, adhesion strength, friction coefficient, and viscosity coefficient are calibrated. Viscosity index and other parameters related to water and sediment two-phase flow of granular rock mass structure in plain area. Through the establishment of a comprehensive evaluation standard, the development level of the whole athlete can be comprehensively evaluated. This paper focuses on the slow human motion sensor used in the detection of human motion.

Nanofluidic chip on tube as standard leak elements

The nanofluidic chips with channels of 100-nm depth and 3-μm width were employed as molecular flow standard leak elements for vacuum technology applications in this paper. The nanofluidic chips are fabricated by MEMS technologies while the macro-micro connection is achieved using glass fusion bonding and standard Swagelok® Fitting. It is found that the choice of annealing temperature and holding time is a key issue regarding fusion bonding and the optimal processing parameters are 780 ℃, 5 min. Meanwhile, the sealing reliability of fusion bonding and the fitting connection is evaluated. Experiment shows that the flow conductance of the as-fabricated leak can reach 10−13 m3∙s−1 magnitude for He, N2 and Ar. This standard leak has the advantages of controlled dimensions, reliable connection, and constant flow conductance over a range of 105 Pa.

Research review of large deformation monitoring of rock and soil

Landslide is a kind of extremely harmful global geological disaster, which often cause serious property losses and casualties. Therefore, scientific and effective landslide monitoring is of great significance for disaster prevention and mitigation. This article introduces the status quo and development trend of landslide deformation monitoring technology in the form of a review. Firstly, the deformation monitoring technologies about rock and soil are summarized and evaluated from three aspects: air (GNSS technology, InSAR technology), sky (UAV technology, 3D laser scanning), and ground (MEMS and Optical fiber technology). Then, the article focuses on ground (deep inclinometer) of the above three aspects, mainly talks about some advanced monitoring technologies used in inclinometer such as fiber Bragg grating and MEMS. The research results show that the inclinometer based on fiber Bragg grating has high monitoring accuracy with 1 με, and the data can be transmitted in time without electromagnetic interference. The MEMS-based inclinometer can measure the vertical tilt angle and horizontal torsion angle, which can realize the three-dimensional deformation monitoring in space. The above research and development of the novel inclinometer provide an effective mean for rock and soil deformation monitoring. Finally, the article summarizes the realization of accurate and reliable monitoring of landslide deformation.

Effect of aluminum alloying on the structure and properties of rapidly quenched TiNiCu alloy

The efficiency of shape memory alloys for the MEMS technology has been recently demonstrated. Quasibinary intermetallic TiNi-TiCu alloys produced by rapid quenching from liquid phase in the form of thin (about 40 um) ribbons are an attractive material for the fabrication of micro-actuators due to their narrow temperature hysteresis of the shape memory effect (SME) and relatively large recoverable strain. In order to broaden the functionality of SME microdevices, in this work we have alloyed TiNiCu containing 25 at.% copper with aluminum. The results have shown that alloying with 0.6 at.% Al increases the cast characteristics of the composition and favors its amorphization. Upon crystallization by isothermal annealing or electropulse treatment the resultant microstructure and SME properties of the Al containing alloy change but slightly in comparison with the original alloy however there is a significant shift (by more than 15°C) of the SME temperature range toward lower temperatures.

Impact of Geometry Dimension on Quality Factor and Mass-Sensitivity of PZT Thin Film-Based MicroCantilevers

The impact of the piezoelectric cantilever geometry and resonant mode on the quality factor and mass-sensitivity were investigated. The piezoelectric cantilevers with Pb(Zr0.52Ti0.48)O3 (PZT) as an active layer were fabricated based on MEMS technology. The PZT thin films were grown on the silicon-on-insulator substrates by pulsed laser deposition. It is shown that the resonant frequency of a defined vibration mode is inversely proportional to the length squared of the piezoelectric cantilever. The experimental results indicated that a shorter cantilever length will contribute to a larger quality factor. The cantilever quality factor has values in a range of 190 to 505, depending on the length and resonant mode. The mass-sensitivity increases when the cantilever length decreases and reaches the highest value of 37.6 Hz/pg for the 100-µm-long cantilever. High-mode vibration was successfully exhibited for the higher mass-detection sensitivity.

An Innovative LC-C Resonant Pressure Sensor Based on Capacitive Feedthroughs

LC resonant wireless passive pressure sensor has been receiving increased attention nowadays. In this paper, an innovative LC-C resonant wireless passive pressure sensor based on dual capacitors was designed and manufactured to replace the traditional LC device. In addition to the inductor and capacitor structure required by the traditional LC device, this paper innovatively designs the fixed capacitor as the inter-layer interconnection structure. The key structural dimensions of the sensor were determined through the numerical analysis of the planar inductor theory and the electromechanical coupling simulation of the dual capacitors model in the previous stage, and the processing of the sensor was carried out through MEMS technology. The final test results showed that within the pressure range of 5kPa to 100kPa, the sensor’s average sensitivity was greater than 69.0 kHz/kPa, while the maximum linear fitting error was smaller than 4.18%. The temperature drift in atmospheric environment was 2.7kHz/°C, and the sensitivity temperature drift was 0.0062kHz/(kPa·°C).

Integration Design of Micro-Electro-Mechanical Encryption System

Optical combination lock is a combination of mechanical combination lock and MEMS technology, which can effectively reduce the size of the combination lock. The mechanism of MEMS optical combination lock and code discriminator, expounds its working principle and structural characteristics, and proposes and verifies the manufacturing process of a set of MEMS optical combination lock discriminator. It not only guarantees the reliability and validity of password transmission, but also has the advantages of easy realization of password diversity and small structure size.

Research of Low-Power MEMS-Based Micro Hotplates Gas Sensor: A Review

In this paper, the research status of low power micro hot plate gas sensor is reviewed. This type of sensor is characterized by the combination of MEMS technology and related insulation measures. Compared with the traditional ceramic tubular sensor, the power consumption of the sensor is greatly reduced, which provides the possibility of remote sensor arrangement and long term stable operation. This paper firstly collects the current sensor-related heat conduction, heat convection and heat radiation theories, and summarizes the calculation model of heat loss in different regions of the micro hot plate gas sensor. Then, the application examples of the finite element method in the analysis of thermal characteristics of the sensor and the common preparation process of the substrate and gas sensitive layer of the micro hot plate are listed. Finally, the main test methods of the stability and gas sensitivity of the micro hot plate gas sensor are summarized.

Study of Array of Mems Inertial Measurement Units Under Quasi-Stationary and Dynamic Conditions

Abstract A measurement system includes all components in a chain of hardware and software that leads from a measured variable to processed data. In that context, the type and quality of the sensors or measuring devices are critical to any measurement system. MEMS/IMU sensors lag behind leading technologies in this respect, but the MEMS/IMU performance rapidly changes while is relatively inexpensive. For this reason, the paper proposes some investigations of currently available MEMS/IMUs, but in an array configuration. The article presents the results of research undertaken on this type of IMU sensor configuration under quasi-stationary and dynamic conditions and answers the question of whether the precision of current MEMS technologies for acceleration and angular velocity sensors is still improved using this kind of approach.

Study on ignition performance of tantalum nitride film energy exchangers based on new bridge area

In order to reduce the ignition energy of the tantalum nitride film transducer, a new type of energy exchangers bridge area was designed in this paper, and it was fabricated by MEMS technology. The parameters of ignition voltage, ignition energy, as well as action time were tested. The experimental results showed that in terms of ignition voltage, ignition energy, and action time, the value of the energy exchangers element of the new bridge area was lower than the value of the energy exchangers element of the conventional bridge area. In addition, ignition performance can be reduced by many energy exchangers in the new bridge area.

Heat Conductivity Based Inner Cavity Pressure Monitoring and Hermeticity Monitoring for Glass Frit Wafer Bonded MEMS Devices

Hermetic sealing is important regarding functionality and reliability for MEMS components. Typically this sealing is done at the wafer level using wafer bonding, which simultaneously provides mechanical protective caps. Here, a universally usable MEMS Foundry technology for inertial sensors and the glass frit bonding to seal them are introduced. A test structure for inner cavity pressure measurement, utilizing the pressure dependence of heat transfer in gasses, which can be realized in this MEMS technology, is introduced and described for use in detailed investigations of factors, which influence the inner cavity pressure in the wafer pre-processing and wafer bonding step itself. These investigations ultimately allowed optimized wafer processing, improved process control, and reliability investigation. We show how, based on the inner cavity pressure measurements, the glass frit bond process can be set up, that side effects such as storing times of the glass frit can be understood, how fine tuning of the bond process can be done, and how both process stability and device reliability can be efficiently be proven.

Temperature and humidity sensor based on MEMS technology

This work presents a monolithically integrated temperature and humidity sensor based on microelectromechanical systems technology. The temperature sensor working on the “bi-metallic” effect has the advantages of wide temperature range, high sensitivity, and fast detection. The humidity sensor has a polyimide parallel plate capacitive structure with the microporous array on the upper electrode designed for high sensitivity and fast response. Numerical analysis and COMSOL simulation showed that the temperature detection sensitivity is 0.2 mV/°C in the range of 193–393 K and humidity sensitivity is 0.405 pF/% relative humidity (RH) with the response time of 34 s in the humidity range of 0%–100% RH. The integrated temperature and humidity sensor has the advantages of small dimension, wide detection range, high precision, and fast response.

A New RF MEMS Power Sensor Based on Double-Deck Thermocouples With High Sensitivity and Large Dynamic Range

This letter reports a new RF MEMS power sensor based on double-deck thermocouples with high sensitivity and a large dynamic range. In order to improve RF sensing capability and sensitivity, the double-deck thermocouples and a MEMS substrate membrane are carefully designed. The proposed RF MEMS power sensor is fabricated by GaAs monolithic microwave integrated circuit (MMIC) process coupled with MEMS technology. Experimental result shows that the output thermovoltage of the device has inherent RF-dc linearity with the power from 1 to 500 mW. And the measured return loss is less than -28.6 dB at 1-20 GHz, which exhibits excellent matching characteristics. Moreover, at 8, 10, and 12 GHz, the measured sensitivities are 133.2, 124.3, and 116.8 μV/mW, respectively. Compared with a traditional thermoelectric power sensor, the sensitivity and the dynamic range of the proposed RF MEMS power sensor are increased by approximately 61% and 2.5 times, respectively. The research work can be considered as an incremental improvement of the state of the art (higher power sensing capability and sensitivity) as RF power sensing using double-deck thermocouples.

Design and Fabrication of a Novel High Power THz Slow Wave Structure Based on MEMS Technology

With the development of TWT in terahertz band, the size of TWT is greatly reduced and the power gain is also reduced. In order to improve the performance of traveling wave tube (TWT), an E-plane and H-plane tapered folded waveguide slow wave structure operating at 0.34THz is designed. In order to reduce the RF loss, a gradual ridge is added to the E-plane ridge. Compared with other ridge loaded structures, the coupling impedance of this structure has been significantly improved, and it has better dispersion characteristics and higher maximum output power. According to the electromagnetic simulation results, under the condition of 16.8kV, 50mA banded electron beam, the maximum output power of the folded waveguide can reach 65.1w, the power gain can reach 31.8db, the 3dB working bandwidth can reach 12GHz, and the electronic efficiency can reach 7.75%. Finally, a complete DRIE process for processing slow wave structure is explored. The slow wave structure is fabricated by combining silicon with non-silicon.

Accurate and controled vehicle pass-by noise emission quantification in real life traffic

Noise emission from individual vehicle largely contributes to city pollution and has serious health impact. The standards towards vehicle manufactures consists in pass-by testing with specific acceleration conditions which are not representative of all real driving. For the 2015/996 EU directive, the vehicle source model is inspired of the preceding pass-by standard with derived data represented the propulsion and rolling noise sources. Anyhow, those sources are underestimated due to driving behavior, aged and modified vehicle, road surface, meteorological conditions... The true data collection of vehicle pass-by would be interesting. Moreover, some of the countries are reflecting on how to fight against those extremely noisy vehicle exceeding noise limit with efficient monitoring systems. This paper presents an innovative tool able to detect, identify and quantify the noise emission of individual pass-by vehicle in real life traffic. It is based on the combination of array and video processing. Compared to the state of the art and thanks to MEMs technology, the system is optimized and designed to quantify the individual noise vehicle emission regarding standard with controlled measurement and accurate processing. If the conditions are not respected to properly qualify the pass-by regarding the system limits, the data are ignored. It aims at constructing large and accurate database useful to determine average noise levels and/or acceptable noise limits per vehicle category.

Applicability of MEMS microphones for environmental sound level monitoring

This paper explores the challenges associated with the integration of MEMS microphone technology into IEC 61672 classified or type-approved environmental sound level monitors. A comparison is drawn between MEMS microphones and electret condenser capsule microphones to highlight key performance differences within the technologies, and a basic integration method for both technologies is suggested. A review of the IEC 61672 and type-approval standards is conducted against the suggested integration method for a MEMS microphone; key shortcomings are reported and objectively reviewed. Development trends for MEMS microphones are explored, providing key insights into the progression of the technology against electret condenser capsule microphones. Furthermore, the evolution of environmental sound level monitoring systems is explored with a key focus on networked and sound localisation technology. The importance of MEMS microphones within the evolution of environmental sound level monitoring systems is presented alongside key arguments for the practical suitability of MEMS technology over electret condenser capsule technology.