Effect of High Tg Mold Compound on MEMS Sensor Package Performance

Estimating wind speed and direction in outdoor areas with high precision and resolution requires a large number of anemometers distributed in different locations. Compared with others conventional sensors, the micro electro mechanical system (MEMS) sensors are lighter and smaller, therefore, they can be integrated in large numbers. Moreover, due to their batch production, MEMS sensors are relatively low cost. Their main drawbacks are the dependence on the air temperature and the inability of detecting the flow direction. This paper deals with the design of a cylindrical-shaped probe equipped with two dual MEMS hot-film sensor chips calibrated in a wind tunnel. With the obtained results, a model based on artificial neural network is developed and implemented on Arduino board. This model is assigned to calculate the corresponding values of wind speed and direction with correcting the effect of temperature drift. Finally, outdoor tests are carried out at wind monitoring points measured by an opto-electronic anemometer and an opto-electronic wind vane. The obtained results are accurate and agree well.

Smart reinforcement steel bars with low-cost MEMS sensors for the structural health monitoring of RC structures

Commonly encountered problems in the manipulation of objects with robotic hands are the contact force control and the setting of approaching motion. Microelectromechanical systems (MEMS) sensors on robots offer several solutions to these problems along with new capabilities. In this review, we analyze tactile, force and/or pressure sensors produced by MEMS technologies including off-the-shelf products such as MEMS barometric sensors. Alone or in conjunction with other sensors, MEMS platforms are considered very promising for robots to detect the contact forces, slippage and the distance to the objects for effective dexterous manipulation. We briefly reviewed several sensing mechanisms and principles, such as capacitive, resistive, piezoresistive and triboelectric, combined with new flexible materials technologies including polymers processing and MEMS-embedded textiles for flexible and snake robots. We demonstrated that without taking up extra space and at the same time remaining lightweight, several MEMS sensors can be integrated into robotic hands to simulate human fingers, gripping, hardness and stiffness sensations. MEMS have high potential of enabling new generation microactuators, microsensors, micro miniature motion-systems (e.g., microrobots) that will be indispensable for health, security, safety and environmental protection.

The procedure of determining the initial values of the attitude angles (pitch, roll, and heading) is known as the alignment. Also, it is essential to align an inertial system before the start of navigation. Unless the inertial system is not aligned with the vehicle, the information provided by MEMS (microelectromechanical system) sensors is not useful for navigating the vehicle. At the moment MEMS gyroscopes have poor characteristics and it’s necessary to develop specific algorithms in order to obtain the attitude information of the object. Most of the standard algorithms for the attitude estimation are not suitable when using MEMS inertial sensors. The wavelet technique, the Kalman filter, and the quaternion are not new in navigation data processing. But the joint use of those techniques for MEMS sensor data processing can give some new results. In this paper the performance of a developed algorithm for the attitude estimation using MEMS IMU (inertial measurement unit) is tested. The obtained results are compared with the attitude output of another commercial GPS/IMU device by Xsens. The impact of MEMS sensor measurement noises on an alignment process is analysed. Some recommendations for the Kalman filter algorithm tuning to decrease standard deviation of the attitude estimation are given.

Flexible and composite structures often develop hidden damages, e.g. cracks or delamination between laminae or phases. Such events could be sensed through embedded structural health monitoring (SHM) systems, but past experimental studies in the literature proved that embedding sensors for SHM purposes may decrease the reliability of the structure, as the sensor acts as an inclusion. In former studies, the authors proposed to adopt a surface-mounted SHM approach based on inertial MEMS (micro electro-mechanical systems) sensors, which has two advantages: it is low cost and also it avoids the afore-mentioned detrimental effects on the endurance limit state of the structure. However, the low accuracy of the MEMS sensors and the type of response that they can measure may hinder an effective monitoring of the structural state; this can be overcome through redundancy and an efficient sensor placement. In this article, an automated approach is discussed for obtaining the optimal topology of a sparse MEMS sensor network. In this regard, the scenarios are assumed unknown in terms of extent and location of stiffness degradation due to damage. The optimal sensor locations are obtained via maximization of the global sensitivity of the measurements to damage. The method can be also implemented in a multi-scale framework, to efficiently handle (micro) sensors, (meso) damaged regions and (macro) structural components of (by far) different sizes. Data related to composite specimens and panels are discussed, with the aim of assessing the identifiability of damage through self-adapting theoretical/numerical (digital) twins of the monitored structures.

Inertial Measurement Units (IMUs) using MEMS (Micro Electro Mechanical Systems) sensors, to detect rotation and acceleration, are extremely sensitive to vibration and shock. Because these IMUs are used in aircraft, missiles, and even in gun launched projectiles, the vibration and shock levels can be extremely high. We have been successful in designing isolation systems that protect the MEMS sensors from these harsh environments. These isolation systems attenuate the shock and vibration in frequency ranges that would otherwise degrade IMU performance and even damage the sensors. In designing an isolation system, for an IMU with MEMS devices, the designer must first acquire a good definition of the shock and vibration environment to which the IMU will be exposed. Then the designer must determine the frequencies and levels to which the MEMS devices are sensitive. Finally the designer must have knowledge of IMU properties such as resonant frequencies, mass properties, clock frequencies, etc. By knowing all of this information, and how it affects IMU performance, the designer can determine the proper parameters for the isolation system. A well designed isolation system using these parameters will be capable of protecting the MEMS devices while maintaining IMU performance through out all specified environments.

This paper reports on a grasping forceps with a triaxial Micro Electro Mechanical Systems (MEMS) tactile sensor on a tip. The laparoscopic surgery is minimally invasive because the incisions are smaller than the open surgery. This results in fast recovery. However, it is a problem in the laparoscopic surgery to damage an organ by localized stress generated by grasping with a thin forceps. To avoid excessive stress applying to the organ, real time evaluation of the stress is important. However, there is no acceptable tool to measure the stress. We propose a grasping forceps with a triaxial MEMS tactile sensor on a tip for a measurement tool. We attached a triaxial MEMS tactile sensor which we have developed on a tip of a grasping forceps. The MEMS sensor can measure not only the pressure but also two directional shear stresses applied to the sensor surface. The sensor size is 7 mm × 7 mm × 2 mm. It is enough small to attach the sensor to the tip of a forceps 12 mm in diameter. In this paper, the characteristics of the forceps with the MEMS sensor during grasping, pushing and pulling actions were evaluated. In these experiments, output of each sensor for pressure and shear stress was proportional to the applied stresses, respectively. Moreover, as an in vivo experiment, we measured the shear stress applied to a pig liver block when it is lifted after being grasped with the forceps. We obtained that the shear stress applied to the liver block increased with the increase of the weight of the liver block.

We describe an experimental and theoretical project centered on the use of nonlinear acoustic shock impulses and microelectromechanical systems (MEMS) sensors to detect and image buried, regular-shaped inclusions at various depths in soil. The use of shock waves is partly motivated by the perceived limited capability of conventional acoustic delivery modes, and by recent research which shows that shock impulses travel efficiently in granular media.

Over the past 30 years, significant progress has been made in the fields of Micro-Electro-Mechanical Systems (MEMS). Originally, the term MEMS was used in the United States to signify electromechanical sensors and actuators that are based on semiconductors. In Europe, the same technology was referred to as “Microsystem Technology,” while in Japan the term micromechatronics was used. Today, the term MEMS refers to all devices, sensors, and actuators that have dimensions in the micrometer range, whether based on semiconductors or other materials such as glass and metals. In this chapter a brief review of the history is provided followed by future trends in the Micro-electro-mechanical Systems (MEMS) industry. We further present materials that are commonly used in the fabrication of MEMS sensors and actuators and we discuss the advantages and disadvantages of each material. Finally, the different types, applications, and recent technologies in MEMS sensors and actuators constitute the core of this chapter.

Nowadays, three-dimensional (3D) integration has been widely applied in semiconductor and electronics industry. When 3D integration applied in MEMS (micro electromechanical system) packaging, it is possible to stack host MEMS chip/wafer with other chips/wafers (such as ASIC) to lower package profile and realize area array sensor system. In this paper, a miniaturized piezoresistive pressure sensor system with TSV structure has been designed to demonstrate the application of TSV in MEMS packaging. TSV in pressure sensor chip is designed to provide communication paths for electrical signals. Cu/Sn bump is electroplated after exposing TSV from backside and backside metallurgy. Signal read-out chip contains redistribution circuits and Au studs. The pressure sensor chip and signal read-out chip are flip chip bonded using Au-Sn eutectic bonding. To realize this pressure sensor system, a systematic process flow including piezoresistors fabrication and circuits patterning, TSV process, flip chip bonding, polymer hermetic sealing is designed and implemented experimentally.

Low-temperature wafer bonding for MEMS packaging utilizing screen-printed sub-micron size Au particle patterns

This paper describes a novel approach method to the heat transfer mechanism beneath isolated bubble during nucleate boiling with MEMS (Micro-Electro-Mechanical Systems) sensors. Fast and local temperature variation beneath an isolated bubble measured with the MEMS sensor obviously showed the microlayer formation, evaporation, dry-out and rewetting phenomena. The heat transfer due to the bubble growth process was numerically evaluated by two-dimensional transient heat conduction simulation with the measured data as a boundary condition. Heat transfer from surrounding superheated liquid layer was also estimated. The approach method was verified through a comparison between a bubble growth process and the heat transfer analysis results both from the heating wall and from the liquid phase. Moreover, the measurement and analysis showed some heat transfer characteristics related to the mechanism of microlayer evaporation, heat transport by an isolated boiling bubble, initial thickness of the microlayer and liquid-vapor interface superheat for high heat flux evaporation.

Fan-out wafer-level packaging (FOWLP) is an interesting platform for Microelectromechanical systems (MEMS) sensor packaging. Employing FOWLP for MEMS sensor packaging has some unique challenges, while some originate merely from the fabrication of redistribution layers (RDL). For instance, it is crucial to protect the delicate structures and fragile membranes during RDL formation. Thus, additive manufacturing (AM) for RDL formation seems to be an auspicious approach, as those challenges are conquered by principle. In this study, by exploiting the benefits of AM, RDLs for fan-out packaging of capacitive micromachined ultrasound transducers (CMUT) were realized via drop-on-demand inkjet printing technology. The long-term reliability of the printed tracks was assessed via temperature cycling tests. The effects of multilayering and implementation of an insulating ramp on the reliability of the conductive tracks were identified. Packaging-induced stresses on CMUT dies were further investigated via laser-Doppler vibrometry (LDV) measurements and the corresponding resonance frequency shift. Conclusively, the bottlenecks of the inkjet-printed RDLs for FOWLP were discussed in detail.

The increasing demand for microelectromechanical systems (MEMS) as, for example, piezoresistive sensors with capabilities of operating at high temperatures, mainly for automotive, petrochemical and aerospace applications, has stimulated the research of alternative materials to silicon in the fabrication of these devices. It is known that the high temperature operating limit for silicon-based MEMS sensors is about 150oC (Fraga, 2009). Silicon carbide (SiC) has shown to be a good alternative to silicon in the development of MEMS sensors for harsh environments due to its excellent electrical characteristics as wide band-gap (3 eV), high breakdown field strength (10 times higher than Si) and low intrinsic carrier concentration which allow stable electronic properties under harsh environments (Cimalla et al., 2007; Wright & Horsfall, 2007; Rajab et al., 2006). In addition, SiC exhibits high elastic modulus at high temperatures which combined with the excellent electronic properties make it very attractive for piezoresistive sensors applications (Kulikovsky et al., 2008). Silicon carbide can be obtained in bulk or film forms. In recent years, great progress has been made in the field of the growth of SiC bulk. Currently there are 6H-SiC, 4H-SiC and 3C-SiC wafers commercially available. However, these wafers are still very expensive (Hobgood et al., 2004; Camassel & Juillaguet, 2007), so encouraging studies on crystalline and amorphous SiC films deposited on silicon or SOI (Silicon-On-Insulator) substrates using appropriate techniques. The use of SiC films besides being less expensive has another advantage which is the well known processing techniques for silicon micromachining. The challenge is to obtain SiC films with mechanical, electrical and piezoresistive properties as good as the bulk form. Nowadays, some research groups have studied the synthesis and characterization of SiC films obtained by different techniques namely, plasma enhanced chemical vapour deposition (PECVD), molecular beam epitaxy (MBE), sputtering, among others, aiming MEMS sensors applications (Chaudhuri et al., 2000; Fissel et al., 1995; Rajagopalan et al., 2003; Lattemann et al., 2003).

Introduction Single atom catalysts have draw increasing attention of enormous researchers due to its atomically disperation on supports, high efficiency and high catalytic performance. Despite those obvious advantages, there is still rare study about the single atom catalyst’s application in sensors. It was firstly reported the palladium single atoms on TiO2 used as a photocatalytic sensing platform to analyzed organophosphorus pesticide chlorpyrifos[1]. Catalyst-based sensing platform opens up a new pathway for exploring novel strategy of design sensors. Micro-electro-mechanical system (MEMS) process have advantages such as, miniaturization, small size, mechanical parts high resonance frequency, and low power consumption. However, the MEMS prepared by traditional method possess poor stability. Here, we employed the atomic layer deposition to prepare ZnO layer on MEMS. Atomic layer deposition (ALD) is a powerful technique for depositing nanoparticles or thin films and has outstanding advantages, including precise control of size and thickness and excellent uniformity[2], except that the substrate is exposed separately to each gaseous precursor and that the deposition is broken into cycles[3]. ALD functionalized method could gain high performance in thermal stability, mechanical and catalytic performance[4]. It was interesting to obtain single atom MEMS sensors via ALD. Method Prior to ALD, MEMS (Shanghai lingpan Electronic Technology Co., Ltd) were put into ethanol and cleaned by ultrasonic agitation for ten minutes. MEMS were put on quartz wafers and dried in air. ZnO films were deposited onto the MEMS by a hot-wall, closed-chamber ALD reactor. N2 (99.999%) was used as carrier gas. The precursors of ZnO were diethyl zinc and water (H2O). Water acts as an oxidant and enables growth over a wide temperature range. The deposition temperature was 150 °C, and the diethyl zinc was kept at room temperature. After the deposition of ZnO layers, Pt single atoms ALD was subsequently deposited with (methylcyclopentadienyl)trimethylplatinum (MeCpPtMe3) and O3 as precursors at the same temperature as our precious work[2]. Ultimately, the MEMS sensors were tested. Results and Conclusions Fig.1 Response performance for ALD SnO2 layer on MEMS It can be seen from the Fig.1 that sensor response increased with the concentration increase gradually. With the concentration increase for about 1 PPM, response value of sensors gradually reduced. It could also be seen that ALD ZnO sensor have a response time of 90 s and recovery time of 120 s. Baseline with drift less than 4 also demonstrated its good stability. It has little increase in response performance as the concentration increased to 80 PPM, it could be caused by the surface electron transfer arrived balance within high concentrations References [1] X. Ge, P. Zhou, Q. Zhang, Z. Xia, S. Chen, P. Gao, Z. Zhang, L. Gu, S. Guo, Palladium single atoms on TiO2 as a photocatalytic sensing platform for analyzing organophosphorus pesticide chlorpyrifos, Angew Chem Int Ed Engl, (2019).[2] Q. Hu, S. Wang, Z. Gao, Y. Li, Q. Zhang, Q. Xiang, Y. Qin, The precise decoration of Pt nanoparticles with Fe oxide by atomic layer deposition for the selective hydrogenation of cinnamaldehyde, Applied Catalysis B: Environmental, 218 (2017) 591-599.[3] Z. Gao, Y. Qin, Design and Properties of Confined Nanocatalysts by Atomic Layer Deposition, Acc Chem Res, 50 (2017) 2309-2316.[4] M.M. Biener, J. Biener, A. Wichmann, A. Wittstock, T.F. Baumann, M. Baumer, A.V. Hamza, ALD functionalized nanoporous gold: thermal stability, mechanical properties, and catalytic activity, Nano Lett, 11 (2011) 3085-3090. Figure 1