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As an essential component of ammunition, pyrotechnics can control ignition with high reliability. However, due to limits of fabrication technology, traditional pyrotechnics are bulky. To achieve both functionality and miniaturization, MEMS pyrotechnics integrate initiator, safety-and-arming (S&A) device and lead charge and keep all components within a small size. MEMS S&A devices, as the core component to ensure system safety, are difficult to achieve active and rapid response to control signals with high safety and reliability. In order to overcome the difficulty, we propose the design and characterization of a MEMS pyrotechnic with a double-layer barrier S&A device. The MEMS pyrotechnic is a high-integrated device with an overall size of 13.4 × 8.5 × 5.2 mm3. The initiator is a NiCr bridge foil covered with an Al/CuO energetic film, which can generate flame when ignited by an excitation voltage. To match the flame energy, lead styphnate is chosen in this study as the lead charge. The S&A device contains four semi-circular barriers, which are directly driven by V-shape electro-thermal actuators to gain active control of the pyrotechnics' ignition condition with rapid response. To improve the system's reliability, the four barriers are axisymmetrically placed in two layers, two barriers for each layer, to constitute a double-layer structure with a thickness of 100 μm. The ignition test results show that the S&A device can prevent the initiator from detonating the lead charge in safety condition. In arming condition, the lead charge will be detonated.

Considering the safety of ammunition, safety and arming (S&A) devices are usually designed in pyrotechnics to control energy transfer through a movable barrier mechanism. To achieve both intelligence and miniaturization, electrothermal actuators are used in MEMS S&A devices, which can drive the barrier to an arming position actively. However, only when the actuators' energy input is continuous can the barrier be stably kept in the arming position to wait for ignition. Here, we propose the design and characterization of a double-layer electrothermal MEMS S&A Device with a bistable mechanism. The S&A device has a double-layer structure and four groups of bistable mechanisms. Each bistable mechanism consists of two V-shape electrothermal actuators to drive a semi-circular barrier and a pawl, respectively, and control their engagement according to a specific operation sequence. Then, the barrier can be kept in the safety or the arming position without energy input. To improve the device's reliability, the four groups of bistable mechanisms are axisymmetrically placed in two layers to constitute a double-layer barrier structure. The test results show that the S&A device can use constant-voltage driving or the capacitor–discharge driving to drive the double-layer barrier to the safety or the arming position and keep it on the position passively by the bistable mechanism. [ABSTRACT FROM AUTHOR]

This work introduces a mixed-transducer micro-origami to achieve efficient vibration, controllable motion, and decoupled sensing. Existing micro-origami systems tend to have only one type of transducer (actuator/sensor), which limits their versatility and functionality because any given transducer system has a narrow range of advantageous working conditions. However, it is possible to harness the benefit of different micro-transducer systems to enhance the performance of functional micro-origami. More specifically, this work introduces a micro-origami system that can integrate the advantages of three transducer systems: strained morph (SM) systems, polymer based electro-thermal (ET) systems, and thin-film lead zirconate titanate (PZT) systems. A versatile photolithography fabrication process is introduced to build this mixed-transducer micro-origami system, and their performance is investigated through experiments and simulation models. This work shows that mixed-transducer micro-origami can achieve power efficient vibration with high frequency, large vibration ranges, and little degradation; can produce decoupled folding motion with good controllability; and can accomplish simultaneous sensing and actuation to detect and interact with external environments and small-scale samples. The superior performance of mixed-transducer micro-origami systems makes them promising tools for micro-manipulation, micro-assembly, biomedical probes, self-sensing metamaterials, and more., (© 2024 The Authors. Small published by Wiley‐VCH GmbH.)

Considering the safety of ammunition, safety and arming (S&A) devices are usually designed in pyrotechnics to control energy transfer through a movable barrier mechanism. To achieve both intelligence and miniaturization, electrothermal actuators are used in MEMS S&A devices, which can drive the barrier to an arming position actively. However, only when the actuators’ energy input is continuous can the barrier be stably kept in the arming position to wait for ignition. Here, we propose the design and characterization of a double-layer electrothermal MEMS S&A Device with a bistable mechanism. The S&A device has a double-layer structure and four groups of bistable mechanisms. Each bistable mechanism consists of two V-shape electrothermal actuators to drive a semi-circular barrier and a pawl, respectively, and control their engagement according to a specific operation sequence. Then, the barrier can be kept in the safety or the arming position without energy input. To improve the device’s reliability, the four groups of bistable mechanisms are axisymmetrically placed in two layers to constitute a double-layer barrier structure. The test results show that the S&A device can use constant-voltage driving or the capacitor–discharge driving to drive the double-layer barrier to the safety or the arming position and keep it on the position passively by the bistable mechanism.

A sub-millimeter sized optical scanner driven by electro-thermal actuation is presented. The scanner is composed of a single-mode optical fiber (SMF) with a cantilevered section at its distal tip. The fiber cantilever is electro-thermally actuated near its base in a single direction and excited at resonance to obtain large deflections at the tip of the fiber. Two-dimensional imaging of an object is demonstrated by simultaneously rotating the object while scanning across its diameter. Illumination light from the optical core of the fiber cantilever is projected through a lens onto the object. Reflected light is collected by the same lens and projected onto a photodetector. An image of the object is reconstructed by interpolation of the detected signal. The resolution of the system was measured to be $16~\mu \text{m}$ by imaging a resolution target. The electro-thermal fiber actuator may provide a new technique for scanning in sub-millimeter sized forward-viewing endoscopic catheters. [ABSTRACT FROM AUTHOR]

The V-shaped electro-thermal MEMS actuator model, with the human error factor taken into account, is presented in this paper through the cascading ANSYS simulation model and the Fuzzy mathematics calculation model. The Fuzzy mathematics calculation model introduces the human error factor into the MEMS actuator model by using the BP neural network, which effectively reduces the error between ANSYS simulation results and experimental results to less than 1%. Meanwhile, the V-shaped electro-thermal MEMS actuator model, with the human error factor included, will become more accurate as the database of the V-shaped electro-thermal actuator model grows.

Highlights • A large displacement bidirectional MEMS stage with interlock mechanism is presented. • The V-shape electro-thermal actuator, micro lever, pawl and slider are investigated respectively. • The rack and interlock mechanism formed by the pawl and slider make the device to have the features of linear output displacement, low power consumption, input signal recognition and displacement retention. Abstract The design, fabrication and characterization of a large displacement bidirectional MEMS stage is presented in this paper. The V-shape electro-thermal actuator, micro lever, pawl and slider are investigated respectively. With 11 V driven voltages, these basic components can generate 15 mN output force and realize pulling, disengaging and reengaging to move the stage forward and backward smoothly (1 mm displacement in bi-direction). The rack and interlock mechanism formed by the pawl and slider make the device to have the features of linear output displacement, low power consumption, input signal recognition and displacement sustaining. SOI wafer is introduced in the fabrication process, and the 1.2 × 3.5 mm2 movable plate can be actuated successfully. [ABSTRACT FROM AUTHOR]

Micro-electromechanical systems (MEMS) safety-and-arming (S&A) device shows great potential in munition miniaturization, and it can be seen as the symbol of the fourth generation of weapons systems. In this paper, the design, fabrication, and actuation performance of a silicon based S&A device is presented. It is a multilayer stacked device, which is composed of the cover plate, the actuation chip, and the barrel plate. The electro-thermal principle is investigated in MEMS scale. With 11 V driving voltages, the structure of V-shape actuator, pawl, and slider can generate 100 μm and 45 μm displacement, and realize pulling, disengaging, and reengaging to change the device from the safety position into armed position smoothly (550 μm displacement). The rack and interlock mechanism formed by the pawl and slider gives the device the features of linear output displacement, low power consumption, input signal recognition, and sustained displacement. The 20,000 g setback acceleration is applied, and no structure damage can be found after the impact, which indicates the good anti-load ability of the MEMS S&A device. In order to solve the contradiction between the functional structure and the fabrication process, different structures are designed separately on different wafers. Both silicon and SOI wafers are used in the fabrication process, and the S&A device has been minimized into 8.5 mm × 8.5 mm × 0.8 mm successfully.

Micro-electro-mechanical system (MEMS) mirrors are widely used for optical modulation, attenuation, steering, switching and tracking. In most cases, MEMS mirrors are packaged in air, resulting in overshoot and ringing upon actuation. In this paper, an electrothermal bimorph MEMS mirror that does not generate overshoot in step response, even operating in air, is reported. This is achieved by properly designing the thermal response time and the mechanical resonance without using any open-loop or closed-loop control. Electrothermal and thermomechanical lumped-element models are established. According to the analysis, when setting the product of the thermal response time and the fundamental resonance frequency to be greater than Q/2π, the mechanical overshoot and oscillation caused by a step signal can be eliminated effectively. This method is verified experimentally with fabricated electrothermal bimorph MEMS mirrors. [ABSTRACT FROM AUTHOR]

This paper presents the design and analysis of a multi degree of freedom (DOF) electro-thermally actuated non-resonant MEMS gyroscope with a 3-DOF drive mode and 1-DOF sense mode system. The 3-DOF drive mode system consists of three masses coupled together using suspension beams. The 1-DOF system consists of a single mass whose motion is decoupled from the drive mode using a decoupling frame. The gyroscope is designed to be operated in the flat region between the first two resonant peaks in drive mode, thus minimizing the effect of environmental and fabrication process variations on device performance. The high gain in the flat operational region is achieved by tuning the suspension beams stiffness. A detailed analytical model, considering the dynamics of both the electro-thermal actuator and multi-mass system, is developed. A parametric optimization is carried out, considering the microfabrication process constraints of the Metal Multi-User MEMS Processes (MetalMUMPs), to achieve high gain. The stiffness of suspension beams is optimized such that the sense mode resonant frequency lies in the flat region between the first two resonant peaks in the drive mode. The results acquired through the developed analytical model are verified with the help of 3D finite element method (FEM)-based simulations. The first three resonant frequencies in the drive mode are designed to be 2.51 kHz, 3.68 kHz, and 5.77 kHz, respectively. The sense mode resonant frequency is designed to be 3.13 kHz. At an actuation voltage of 0.2 V, the dynamically amplified drive mode gain in the sense mass is obtained to be 18.6 µm. With this gain, a capacitive change of 28.11 f F and 862.13 f F is achieved corresponding to the sense mode amplitude of 0.15 μ m and 4.5 μ m at atmospheric air pressure and in a vacuum, respectively.

This paper proposes a rapid fabrication process for miniaturized electro-thermal grippers by using silver-nickel composite ink. Thick resistive structures are dispensed on a silicon wafer by a dispenser, and the parameters of the dispenser can be controlled for different thicknesses of hot and cold arms in a micro-gripper. The fabricated single layer structures are almost symmetric about a central plane of symmetry, thus largely suppressing the out-of-plane deflection. Due to cross-sectional area difference of the cold and hot arms, the micro-gripper can be driven by applying dc voltages. Electrical and mechanical behaviors of the micro-grippers are simulated and tested, and the simulation results are in accordance with the experiment results. The simulated maximum temperature is 155 °C, and occurs at the hot arms with an input voltage of 1.54 V. The measured displacement of the micro-gripper is observed to be 311 μm for an applied current of 0.26 A with maximum power dissipation of 0.4 W. The fabricated micro-gripper can grip a small styrofoam ball with a diameter of 1.3 mm between both tips. [ABSTRACT FROM AUTHOR]

This paper presents the designs for a new configuration of an electro-thermally actuated SU-8 polymeric micromanipulator for biological and MEMS components manipulations. Two models are proposed with the following dimensions of the arms: 400 and respectively 800 μm length, for a thickness of around 20-25 μm. The electro-thermally driven micromanipulators have been studied using computer simulations, based on finite element method performed with CoventorWare software tool. Results from performed numerical coupled electro-thermo-mechanical and transient electro-thermal simulations have been used to analyze both static and dynamic behavior of the micromanipulator. The influence of the achieved temperature in the arms along with the in-plane tips deflections as a function of the applied voltage has been investigated. The numerical investigations show a good mechanical behavior of the micromanipulators (displacement of the arms up to 10 μm for the first model and 20 μm for the second one). Also, the handling force (between 0 and 36 μN) of the designed micromanipulators has been investigated. [ABSTRACT FROM AUTHOR]

Laser-induced graphene (LIG) represents a fast-speed and low-cost method to prepare the customizable graphene-based patterns in complex configurations with exceptional electrical performance. This paper presents the applications of LIG formed on the commercial polyimide (PI) film as the stretchable strain sensor and electrical-actuated actuators. First, the conductive performances of the LIG were systematically revealed under different fabrication conditions via investigating the effects of processing parameters, and the fluence of the laser was experimentally demonstrated as the only crucial parameter to evaluate the LIG formation, facilitating the selection of optimized manufacturing parameters to prepare the LIG with desired electrical performances. Then, the LIG-based strain sensor which can undergo over 50% tensile strain was fabricated by transfer of the LIG from the PI film to polydimethylsiloxane. The variety of LIG-based electro-thermal actuators to achieve pre-designed 3D architectures was presented, along with their parameter analysis. After incorporating the multimeter system, the actuator can even feedback its transformation from 2D precursor to 3D architecture by monitoring the resistance variation of LIG, revealing the integrated capability of our design in serving as sensors and actuators. Finally, the wearable glove with the LIG sensors was presented to demonstrate its ability to remotely control the soft robotic hand.

MEMS based heatuators are being used extensively for actuation purposes. The conventional heatuators have different arm widths while this paper proposes a variant design that has equal widths but unequal resistances. The new design brings in the advantages of faster response and greater deflections for similar conditions. The heatuators have been simulated using the coupledfield element SOLID98 of the finite element analysis software ANSYS. [ABSTRACT FROM AUTHOR]

The V-shaped electro-thermal MEMS actuator model, with the human error factor taken into account, is presented in this paper through the cascading ANSYS simulation model and the Fuzzy mathematics calculation model. The Fuzzy mathematics calculation model introduces the human error factor into the MEMS actuator model by using the BP neural network, which effectively reduces the error between ANSYS simulation results and experimental results to less than 1%. Meanwhile, the V-shaped electro-thermal MEMS actuator model, with the human error factor included, will become more accurate as the database of the V-shaped electro-thermal actuator model grows. [ABSTRACT FROM AUTHOR]

Micro-electromechanical systems (MEMS) safety-and-arming (S&A) device shows great potential in munition miniaturization, and it can be seen as the symbol of the fourth generation of weapons systems. In this paper, the design, fabrication, and actuation performance of a silicon based S&A device is presented. It is a multilayer stacked device, which is composed of the cover plate, the actuation chip, and the barrel plate. The electro-thermal principle is investigated in MEMS scale. With 11 V driving voltages, the structure of V-shape actuator, pawl, and slider can generate 100 μm and 45 μm displacement, and realize pulling, disengaging, and reengaging to change the device from the safety position into armed position smoothly (550 μm displacement). The rack and interlock mechanism formed by the pawl and slider gives the device the features of linear output displacement, low power consumption, input signal recognition, and sustained displacement. The 20,000 g setback acceleration is applied, and no structure damage can be found after the impact, which indicates the good anti-load ability of the MEMS S&A device. In order to solve the contradiction between the functional structure and the fabrication process, different structures are designed separately on different wafers. Both silicon and SOI wafers are used in the fabrication process, and the S&A device has been minimized into 8.5 mm × 8.5 mm × 0.8 mm successfully. [ABSTRACT FROM AUTHOR]

This paper presents the design and analysis of a multi degree of freedom (DOF) electro-thermally actuated non-resonant MEMS gyroscope with a 3-DOF drive mode and 1-DOF sense mode system. The 3-DOF drive mode system consists of three masses coupled together using suspension beams. The 1-DOF system consists of a single mass whose motion is decoupled from the drive mode using a decoupling frame. The gyroscope is designed to be operated in the flat region between the first two resonant peaks in drive mode, thus minimizing the effect of environmental and fabrication process variations on device performance. The high gain in the flat operational region is achieved by tuning the suspension beams stiffness. A detailed analytical model, considering the dynamics of both the electro-thermal actuator and multi-mass system, is developed. A parametric optimization is carried out, considering the microfabrication process constraints of the Metal Multi-User MEMS Processes (MetalMUMPs), to achieve high gain. The stiffness of suspension beams is optimized such that the sense mode resonant frequency lies in the flat region between the first two resonant peaks in the drive mode. The results acquired through the developed analytical model are verified with the help of 3D finite element method (FEM)-based simulations. The first three resonant frequencies in the drive mode are designed to be 2.51 kHz, 3.68 kHz, and 5.77 kHz, respectively. The sense mode resonant frequency is designed to be 3.13 kHz. At an actuation voltage of 0.2 V, the dynamically amplified drive mode gain in the sense mass is obtained to be 18.6 µm. With this gain, a capacitive change of 28.11   f F and 862.13   f F is achieved corresponding to the sense mode amplitude of 0.15   μ m and 4.5   μ m at atmospheric air pressure and in a vacuum, respectively. [ABSTRACT FROM AUTHOR]

Micro-electro-mechanical system (MEMS) mirrors are widely used for optical modulation, attenuation, steering, switching and tracking. In most cases, MEMS mirrors are packaged in air, resulting in overshoot and ringing upon actuation. In this paper, an electrothermal bimorph MEMS mirror that does not generate overshoot in step response, even operating in air, is reported. This is achieved by properly designing the thermal response time and the mechanical resonance without using any open-loop or closed-loop control. Electrothermal and thermomechanical lumped-element models are established. According to the analysis, when setting the product of the thermal response time and the fundamental resonance frequency to be greater than Q/2π, the mechanical overshoot and oscillation caused by a step signal can be eliminated effectively. This method is verified experimentally with fabricated electrothermal bimorph MEMS mirrors., Competing Interests: The authors declare no conflict of interest.