Mixed-Transducer Micro-Origami for Efficient Motion and Decoupled Sensing.

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.

SOI MEMS Electro-Thermal Actuators for Biomedical Applications: Operation in 0.9% NaCl Solution.

In recent years, the immense potential for MEMS devices in the biomedical industry has been understood. It has been determined that, among their many plausible functions, their use may also extend to single human red blood cell diagnostics, whereby biomarkers of quantifiable magnitudes may be detected. Without a doubt, the mechanical and thermal specifications by which potential devices must be able to function are very strict. Among them is the ability to operate while fully submerged in aqueous solutions. In this work, six devices were modelled numerically in deionised (DI) water and 0.9 wt% NaCl solution, the results of which were validated experimentally. The mechanical performance of the different devices when fully submerged in 0.9 wt% NaCl solution is hereby discussed. With the exception of one, all the devices in their current configuration are confirmed to be suitable candidates for biomedical applications.

Design of a Double-Layer Electrothermal MEMS Safety and Arming Device with a Bistable Mechanism.

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.

Stretchable Sensors and Electro-Thermal Actuators with Self-Sensing Capability Using the Laser-Induced Graphene Technology.

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.

Macro Modeling of V-Shaped Electro-Thermal MEMS Actuator with Human Error Factor.

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.

The Research on Actuation Performance of MEMS Safety-and-Arming Device with Interlock Mechanism.

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.

Design and Analysis of a High-Gain and Robust Multi-DOF Electro-thermally Actuated MEMS Gyroscope.

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.

Modelling and Experimental Verification of Step Response Overshoot Removal in Electrothermally-Actuated MEMS Mirrors.

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.