Microelectromechanical Systems Switches Research Articles

The Seven-State RF MEMS Miniaturized Broadband Reconfigurable Step Attenuator.

This paper presents a three-channel reconfigurable step attenuator based on radio frequency (RF) microelectromechanical system (MEMS) switches, in response to the current issues of high insertion loss and low attenuation accuracy of attenuators. The coplanar waveguide (CPW), cross-shaped power dividers, RF MEMS switches, and π-type attenuation resistor networks are designed as a basic unit of the attenuator. The attenuator implemented attenuation of 0~30 dB at 5 dB intervals in the frequency range of 1~25 GHz through two basic units. The results show that the insertion loss is less than 1.41 dB, the attenuation accuracy is better than 2.48 dB, and the geometric size is 2.4 mm × 4.0 mm × 0.7 mm. The attenuator can be applied to numerous fields such as radar, satellites, aerospace, electronic communication, and so on.

Stress Suppression Design for Radiofrequency Microelectromechanical System Switch Based on a Flexible Substrate.

A novel stress suppression design for flexible RF MEMS switches has been presented and demonstrated through theoretical and experimental research to isolate the stress caused by substrate bending. An RF MEMS switch with an S-shaped microspring structure was fabricated by the two-step etching process as a developmental step toward miniaturization and high reliability. The RF MEMS switches with an S-shaped microspring exhibited superior microwave performance and stable driving voltage under different substrate curvatures compared to the conventional non-microspring switches, demonstrating that the bending stress is successfully suppressed by the S-shaped microspring and the island structure. Furthermore, this innovative design could be easily extended to other flexible devices.

Frequency reconfigurable microstrip patch antenna for multiband applications

Wireless communication technology is well-established, and several antennas have been developed and produced specifically for this purpose. However, antenna performance and communication system development need to be enhanced in order to adapt to the present era. The performance of the antenna is significantly influenced by its design. Thus, this work produced a novel wideband antenna design via the use of a frequency reconfigurable approach. In the recommended study, microstrip patch antennas (MPAs) were used in wideband applications to switch frequencies using shunt-series microelectromechanical systems (MEMS). The suggested antenna, which has two switches built into it, is tested in ON-ON, OFF-ON, and OFF-OFF switching scenarios. Radiation pattern, voltage standing wave ratio (VSWR), gain, bandwidth, and return loss are among the antenna performance metrics used to assess the suggested antenna's performance in each switching situation. The simulation findings suggest that the optimal antenna design for usage in wireless communication systems is one that works well with a shunt-series MEMS switch.

Comprehensive Review of RF MEMS Switches in Satellite Communications.

The miniaturization and low power consumption characteristics of RF MEMS (Radio Frequency Microelectromechanical System) switches provide new possibilities for the development of microsatellites and nanosatellites, which will play an increasingly important role in future space missions. This paper provides a comprehensive review of RF MEMS switches in satellite communication, detailing their working mechanisms, performance optimization strategies, and applications in reconfigurable antennas. It explores various driving mechanisms (electrostatic, piezoelectric, electromagnetic, thermoelectric) and contact mechanisms (capacitive, ohmic), highlighting their advantages, challenges, and advancements. The paper emphasizes strategies to enhance switch reliability and RF performance, including minimizing the impact of shocks, reducing driving voltage, improving contacts, and appropriate packaging. Finally, it discusses the enormous potential of RF MEMS switches in future satellite communications, addressing their technical advantages, challenges, and the necessity for further research to optimize design and manufacturing for broader applications and increased efficiency in space missions. The research findings of this review can serve as a reference for further design and improvement of RF MEMS switches, which are expected to play a more important role in future aerospace communication systems.

Characterizing MEMS Switch Reliability for Cryogenic Applications such as Quantum Computing

Micro Electromechanical Systems (MEMS) switches offer many advantages over conventional larger switches. One potential application we are exploring is the use of commercial radio frequency (RF) MEMS switches for quantum computing applications. However, it is well-documented that cryogenic temperatures can cause mechanical reliability issues for MEMS. Furthermore, commercial RF MEMS switches are designed for room temperature operation, thus their reliability at cryogenic temperatures is unknown. Commercial MEMS switches are also packaged inside sealed housings, which prevent the use of optical methods for characterization and inspection. We are therefore developing test methods to evaluate the reliability of commercial RF MEMS switches at cryogenic temperatures. We describe our test methods and preliminary reliability test data from room temperature down to 55 K.

Improved Test Fixture for Collecting Microcontact Performance and Reliability Data.

Microelectromechanical systems (MEMS) ohmic contact switches are considered to be a promising candidate for wireless communication applications. The longevity of MEMS switches is directly related to the reliability and performance of microcontacts. In this work, an improved microcontact test fixture with high actuation rates (KHz) and highly precise position control (nm) and force (nN) control was developed. Here, we collected microcontact performance data from initial contact tests (ICT) and microcontact reliability data from cold switched tests (CST). To perform these tests with our test fixture, we fabricated MEMS microcontact test structures with relatively high Young's modulus electroplated Nickel (Ni)-based, fixed-fixed beam structure with Au/RuO2 bimetallic microcontacts. These structures were characterized for forces ranging from 200-1000 µN in ICT tests. In a CST test, the tested microcontact survived more than 200 million cycles at a 1 KHz cycle rate, with a stable contact resistance value ranging between 3.8-5.2 Ω. These experiments validate the potentiality of our microcontact test fixture, and will facilitate further investigation on advanced microcontacts to enhance the MEMS switch's reliability.

MEMS Switch Realities: Addressing Challenges and Pioneering Solutions.

Micro-Electro-Mechanical System (MEMS) switches have emerged as pivotal components in the realm of miniature electronic devices, promising unprecedented advancements in size, power consumption, and versatility. This literature review paper meticulously examines the key issues and challenges encountered in the development and application of MEMS switches. The comprehensive survey encompasses critical aspects such as material selection, fabrication intricacies, performance metrics including switching time and reliability, and the impact of these switches on diverse technological domains. The review critically analyzes the influence of design parameters, actuation mechanisms, and material properties on the performance of MEMS switches. Additionally, it explores recent advancements, breakthroughs, and innovative solutions proposed by researchers to address these challenges. The synthesis of the existing literature not only elucidates the current state of MEMS switch technology but also paves the way for future research avenues. The findings presented herein serve as a valuable resource for researchers, engineers, and technologists engaged in advancing MEMS switch technology, offering insights into the current landscape and guiding future endeavors in this rapidly evolving field.

Implementation of Highly Reliable Contacts for RF MEMS Switches.

A contact is the key structure of RF MEMS (Radio Frequency Microelectromechanical System) switches, which has a direct impact on the switch's electrical and mechanical properties. In this paper, the implementation of highly reliable contacts for direct-contact RF MEMS switches is provided. As a soft metal material, gold has the advantages of low contact resistance, high chemical stability, and mature process preparation, so it is chosen as the metal material for the beam structure as well as the contacts of the switch. However, a Pt film is used in the bottom contact area to enhance the reliability of the contact. Three kinds of contacts with various shapes are fabricated using different processes. Particularly, a circular-shaped contact is obtained by dry/wet combined processes. The detailed fabrication process of the contacts as well as the Pt film on the bottom contact area are given. The experimental test shows that the contact shape has little effect on the RF performance of the switches. However, the circular contact shows better reliability than other contacts and can work well even after 1.2 × 109 cycles.

Ultrabroadband (DC–80 GHz) RF MEMS DC/capacitive load shunt switch

AbstractThis study presents the design and fabrication of a novel direct current (DC)/capacitive radio frequency (RF) Micro‐Electro‐Mechanical Systems (MEMS) switch in the ultrabroadband range from DC to 80 GHz. This proposed RF MEMS switch consists of two arms, with one arm providing a DC loading state (), whereas the second arm provides a capacitive loading state () to the ground when pull‐in voltage is applied. Insertion loss less than 1.85 dB and return loss better than 10 dB are achieved in the OFF state () from DC to 80 GHz (no pull‐in voltage is applied). Due to the novel design topology, this switch can act as a DC‐only switch (0–17 GHz) that provides isolation better than 25 dB during the state. A capacitive‐only switch (48–80 GHz) provides isolation better than 17 dB. This proposed structure can act as either DC(S1) or a capacitive () switch (17–48 GHz) and provides isolation better than 10 dB in either state. This proposed switch finds its best application in reconfigurable circuits like phase shifters due to switching between DC and capacitive loading during the On state from 17 to 48 GHz. The proposed switch's measured pull‐in and lift‐off voltages are 3.5 and 2.85 V, respectively.

Design of a Ka-Band Five-Bit MEMS Delay with a Coplanar Waveguide Loaded U-Shaped Slit.

This paper designs a five-bit microelectromechanical system (MEMS) time delay consisting of a single-pole six-throw (SP6T) RF switch and a coplanar waveguide (CPW) microstrip line. The focus is on the switch upper electrode design, power divider design, transmission line corner compensation structure design, CPW loading U-shaped slit structure design, and system simulation. The switch adopts a triangular upper electrode structure to reduce the cantilever beam equivalent elastic coefficient and the closed contact area to achieve low drive voltage and high isolation. The SP6T RF MEMS switch uses a disc-type power divider to achieve consistent RF performance across the output ports. When designed by loading U-shaped slit on transmission lines and step-compensated tangents at corners, the system loss is reduced, and the delay amount is improved. In addition, the overall size of the device is 2.1 mm × 2.4 mm × 0.5 mm, simulation results show that the device has a delay amount of 0-60 ps in the frequency range of 26.5-40 GHz, the delay accuracy at the center frequency is better than 0.63 ps, the delay error in the whole frequency band is less than 22.2%, the maximum insertion loss is 3.69 dB, and the input-output return rejection is better than 21.54 dB.

Revolutionizing wireless communication: A review perspective on design and optimization of RF MEMS switches

Micro Electro Mechanical System (MEMS) technology revolutionized electronics by enabling miniaturization and integration of components like sensors, actuators, & switches. MEMS switches offer advantages over conventional switches, with Radio Frequency (RF) MEMS switches gaining attention in wireless communication systems. Designing and optimizing RF MEMS switches necessitate a profound comprehension of their electromagnetic and mechanical behavior, achieved using simulation and optimization techniques. This review provides an overview of different optimization techniques, including Finite Difference Time Domain (FDTD), Finite Element Method (FEM), Method of moments (MoM), Taguchi method, Response Surface Method (RSM), Artificial Neural Network (ANN) model and Evolutionary Algorithm (EA) based model, with the ANN and EA model being the most efficient due to its capability to handle complex designs and provide accurate predictions. This review aims to provide insights into the current state-of-the-art in RF MEMS switch design and optimization, stimulating further research to address existing challenges and limitations.

A Threshold Helium Leakage Detection Switch with Ultra Low Power Operation.

Detecting helium leakage is important in many applications, such as in dry cask nuclear waste storage systems. This work develops a helium detection system based on the relative permittivity (dielectric constant) difference between air and helium. This difference changes the status of an electrostatic microelectromechanical system (MEMS) switch. The switch is a capacitive-based device and requires a very negligible amount of power. Exciting the switch's electrical resonance enhances the MEMS switch sensitivity to detect low helium concentration. This work simulates two different MEMS switch configurations: a cantilever-based MEMS modeled as a single-degree-freedom model and a clamped-clamped beam MEMS molded using the COMSOL Multiphysics finite-element software. While both configurations demonstrate the switch's simple operation concept, the clamped-clamped beam was selected for detailed parametric characterization due to its comprehensive modeling approach. The beam detects at least 5% helium concentration levels when excited at 3.8 MHz, near electrical resonance. The switch performance decreases at lower excitation frequencies or increases the circuit resistance. The MEMS sensor detection level was relatively immune to beam thickness and parasitic capacitance changes. However, higher parasitic capacitance increases the switch's susceptibility to errors, fluctuations, and uncertainties.

Design and Analysis of a Fluid-Filled RF MEMS Switch

In the present study, a fluid-filled RF MEMS (Radio Frequency Micro-Electro-Mechanical Systems) switch is proposed and designed. In the analysis of the operating principle of the proposed switch, air, water, glycerol and silicone oil were adopted as filling dielectric to simulate and research the influence of the insulating liquid on the drive voltage, impact velocity, response time, and switching capacity of the RF MEMS switch. The results show that by filling the switch with insulating liquid, the driving voltage can be effectively reduced, while the impact velocity of the upper plate to the lower plate is also reduced. The high dielectric constant of the filling medium leads to a lower switching capacitance ratio, which affects the performance of the switch to some extent. By comparing the threshold voltage, impact velocity, capacitance ratio, and insertion loss of the switch filled with different media with the filling media of air, water, glycerol, and silicone oil, silicone oil was finally selected as the liquid filling medium for the switch. The results show that the threshold voltage is 26.55 V after filling with silicone oil, which is 43% lower under the same air-encapsulated switching conditions. When the trigger voltage is 30.02 V, the response time is 10.12 μs and the impact speed is only 0.35 m/s. The frequency 0-20 GHz switch works well, and the insertion loss is 0.84 dB. To a certain extent, it provides a reference value for the fabrication of RF MEMS switches.

Design and Fabrication of a MEMS Bandpass Filter with Different Center Frequency of 8.5-12 GHz.

The design simulation and fabrication results of a bandpass filter based on micro-electro-mechanical system (MEMS) switches are presented in this paper. The MEMS filter element consists of a MEMS capacitance switch and two resonant rings that are fixed onto coplanar waveguide lines through anchor points. The micromachine characteristics of the filter could be optimized to change the center frequency from 8.5 to 12 GHz by improving the geometrical parameters; other electrical parameters of the filter, such as stopband rejection, insertion loss, and return loss at each center frequency, were simulated and calculated. In order to evaluate the MEMS filter design methodology, a filter working at 10.5 GHz fabricated with an aluminum top electrode was used, and it displayed a low insertion loss of 1.12 dB and a high stopband rejection of 28.3 dB. Compared with the simulation results, these proposed filter showed better electrical performance. Our results demonstrated that the filter with the integrated RF MEMS switch not only provides the benefit of reduced size compared with a traditional filter, but also improves stopband rejection, insertion loss, and return loss.

The Design and Fabrication of a MEMS Electronic Calibration Chip.

During the test of microelectromechanical system (MEMS) devices, calibration of test cables, loads and test instruments is an indispensable step. Calibration kits with high accuracy, great operability and small loss can reduce the systematic errors in the test process to the greatest extent and improve the measurement accuracy. Aiming at the issues of the conventional discrete calibration piece unit, which presents cumbersome calibration steps and large system loss, an integrated electronic calibration chip based on frequency microelectromechanical system (RF MEMS) switches is designed and fabricated. The short-open-load-through (SOLT) calibration states can be completed on a single chip, step by step, by adjusting the on-off state of the RF MEMS switches. The simulation results show that the operating frequency of the electronic calibration piece covers the range of DC~26.5 GHz, the insertion loss in through (thru) state is less than 0.2 dB, the return loss is less than 1.0 dB in short-circuit and open-circuit states, the return loss under load-circuit state is less than 20 dB and its size is only 2.748 mm × 2.2 mm × 0.5 mm. This novel calibration chip design has certain esteem for advancing calibration exactness and effectiveness.

Flexible radio-frequency micro electro-mechanical switch towards the applications of satellite communications

This paper presents a flexible radio-frequency microelectromechanical system (RF MEMS) switch integrated on cyclo-olefin polymer (COP) substrate using a modified surface MEMS processing technology, which could be used in the 17–19 GHz frequency band of satellite communication. Through systematic simulation analysis, it is found that flexible RF MEMS switch can achieve certain bending radius by miniaturizing the electronic dimension, without degrading the RF performance. It is demonstrated that the RF characteristics of flexible RF MEMS switch with special anchor structural design, fabricated by modified surface MEMS processing, are not sensitive to bending deformation under the curvature of 0 mm−1, 0.05 mm−1, 0.10 mm−1. Furthermore, the range of bending curvature which will affect the RF characteristics is given through systematic simulation. The flexible RF MEMS switch with high process compatibility and stable RF performance is believed to be promising candidates for future microwave communications and other consumer electronics.

Recent Advances in Flexible RF MEMS.

Microelectromechanical systems (MEMS) that are based on flexible substrates are widely used in flexible, reconfigurable radio frequency (RF) systems, such as RF MEMS switches, phase shifters, reconfigurable antennas, phased array antennas and resonators, etc. When attempting to accommodate flexible deformation with the movable structures of MEMS, flexible RF MEMS are far more difficult to structurally design and fabricate than rigid MEMS devices or other types of flexible electronics. In this review, we survey flexible RF MEMS with different functions, their flexible film materials and their fabrication process technologies. In addition, a fabrication process for reconfigurable three-dimensional (3D) RF devices based on mechanically guided assembly is introduced. The review is very helpful to understand the overall advances in flexible RF MEMS, and serves the purpose of providing a reference source for innovative researchers working in this field.

Features measurement analysis of pull-in voltage for embedded MEMS

<p>The embedded micro electro mechanical systems (MEMS) is a technology that is creating a new era in all fields and especially in the internet of things (IoT) field. MEMS are necessary components for the realization of tiny micro/nano circuits. For this reason, designers are facing many challenges in designing embedded MEMS for achieving efficient products. The pull-in voltage is one of the most important parameters of MEMS design. In this work, we are interested in the analysis of some geometrical and mechanical parameters for the pull-in. The objective is to study of the concept of pull-in voltage in order to reduce it. First, we made a simulation to choose the appropriate material achieving a lower pull-in voltage. Then, we analysed the impact of geometrical parameters on the pull-in voltage. In this work, Finite element method using COMSOL Multiphysics® software is employed to compute the Pull-in voltage and study the behaviour of the MEMS Switch in order to optimize it. Pull-in voltage can be reduced by careful selection of the cantilever material and it can be further reduced by changing the beam parameters.</p>

MEMS Switching Voltage Regulator Using a Normally-On Electret Relay

We report on a DC/DC step-down switching regulator using a microelectromechanical systems (MEMS) switch for the first time. The output voltage developed in a storage capacitor is used as a feedback control voltage for the electrostatic actuator that drives a micromechanical contact switch inserted between the rectifier and the capacitor. The switch is configured to be normally-on owing to the electrostatic potential remaining in the electret film on the electrodes. When the output voltage exceeds and the feedback control voltage cancels the built-in potential of the electret, the differential voltage acting on the actuator becomes small and the contact is opened, thereby decoupling the rectifier from the storage capacitor. When the output voltage becomes low, on the other hand, the net differential voltage becomes large and the contact is closed again, thereby reconnecting the rectifier to the capacitor and recovering the voltage. Fast repetition of this sequence maintains the DC voltage of the storage capacitor at a constant level. For demonstration, an electret film that is pre-charted to 240 V is used to regulate the output voltage in a range between 12 V and 14 V. Different from the switching regulators using transistors, the MEMS regulator does not require any bias current for operation, being suitable as a low-power voltage regulator for environmental energy harvesters. [2021-0220]

Self-Powered and Autonomous Vibrational Wake-Up System Based on Triboelectric Nanogenerators and MEMS Switch.

With the extensive application of wireless sensing nodes, the demand for sustainable energy in unattended environments is increasing. Here, we report a self-powered and autonomous vibrational wake-up system (SAVWS) based on triboelectric nanogenerators and micro-electromechanical system (MEMS) switches. The energy triboelectric nanogenerator (E-TENG) harvests vibration energy to power the wireless transmitter through a MEMS switch. The signal triboelectric nanogenerator (S-TENG) controls the state of the MEMS switch as a self-powered accelerometer and shows good linearity in the acceleration range of 1–4.5 m/s2 at 30 Hz with a sensitivity of about 14.6 V/(m/s2). When the acceleration increases, the S-TENG turns on the MEMS switch, and the wireless transmitter transmits an alarm signal with the energy from E-TENG, using only 0.64 mJ. Using TENGs simultaneously as an energy source and a sensor, the SAVWS provides a self-powered vibration monitoring solution for unattended environments and shows extensive applications and great promise in smart factories, autonomous driving, and the Internet of Things.