The development of a high-performance, low-cost, and simply fabricated flexible three-dimensional (3D) force sensor is essential for the future development of electronic skins suitable for the detection of normal and shear forces for several human motions. In this study, a sandwich-structured flexible 3D force tactile sensor based on a polyethylene-carbon composite material (velostat) is presented. The sensor has a large measuring range, namely, 0–12 N in the direction of the normal force and 0–2.6 N in the direction of the shear force. For normal forces, the sensitivity is 0.775 N⁻¹ at 0–1 N, 0.107 N⁻¹ between 1 and 3 N, and 0.003 N⁻¹ at 3 N and above. For shear forces, the measured sensitivity is 0.122 and 0.12 N⁻¹ in x- and y-directions, respectively. Additionally, the sensor exhibits good repeatability and stability after 2500 cycles of loading and releasing. The response and recovery times of the sensor are as fast as 40 and 80 ms, respectively. Furthermore, we prepared a glove-like sensor array. When grasping the object using the tactile glove, the information about the force applied to the sensing unit can be transmitted through a wireless system in real-time and displayed on a personal computer (PC). The prepared flexible 3D force sensor shows broad application prospects in the field of smart wearable devices.

An electrode material with high performance, long durability, and low cost for supercapacitors has long been desired in academia and industry. Among all the factors that affect the electrochemical performance and cycling stability of electrode materials, the morphology and intrinsic structure characteristics are the most important. In this study, a novel 3D flower-like Ce(COOH)₃ electrode material was designed by taking advantage of the Ce³⁺ and -COOH groups and fabricated by a one-pot microwave-assisted method. The morphology and structure characteristics of the sample were examined by SEM, EDS, TEM, XRD, FT-IR, XPS, N₂ adsorption/desorption techniques, and the electrochemical behaviors were investigated in a three-electrode configuration. The Ce(COOH)₃ electrode presents an excellent specific capacitance of 140 F g⁻¹ at 1 A g⁻¹, higher than many other previously reported Ce-based electrodes. In addition, it delivers high rate capability that retains 60% of its initial capacitance when the current density is magnified 20 times. Dramatically, the Ce(COOH)₃ electrode exhibits an ultra-high cycling stability with capacitance retention of 107.9% after 60,000 cycles, which is the highest durability among reported Ce–organic compound electrodes to the best of our knowledge. The excellent electrochemical performance is ascribed to its intrinsic crystal structure and unique morphology. This work indicates that the 3D flower-like Ce(COOH)₃ has significant potential for supercapacitor applications and the facile and scalable synthesis strategy can be extended to produce other metal–organic composite electrodes.

Electromigration (EM) in solder joints under high current density has become a critical reliability issue for the future high density microelectronic packaging. This paper presents atomic density redistribution algorithm for predicting electromigration induced void nucleation and growth in solder joints of Chip Scale Package (CSP) structure. The driving force for electromigration induced failure considered here includes the electron wind force, stress gradients, temperature gradients, as well as the atomic density gradient, which were neglected in many of the existing studies on electromigration. The simulation results for void generation and time to failure (TTF) are discussed and correlated with the previous test results. EM sensitivity analysis is also performed to investigate the effect of EM parameters and mechanical properties of material on electromigration failure. The simulation results indicated that the atomic density on the activation energy is quite sensitive, and the mechanical material parameters have no impact on EM sensitivity of normalized atomic density.

Thermal simulation and analysis play a significant role in development of new generation of IC package design. However, in general IC design engineers and package engineers do not have the skills of performing such simulation and analysis. One way of overcoming tins problem is to develop a tool which can perform thermal analysis on package models automatically. Based on tins idea, a customized tool called WBExcel is developed with ANSYS workbench and Excel. It is easy for user to input necessary data in an intuitive Excel spreadsheet. After that the whole thermal simulation (including meshing, loading/boundary condition, solving, post-process and thermal results) will be completed automatically and efficiently. Tins paper introduces the general methodology of the simulation interface and system. This simulation tool has been applied to MLP package family and the results agree well with those from the normal ANSYS simulation and measurement.

The present study proposed a novel polymer optical fiber sensor design for vibration measuring. The sensor design consists of two fibers; primary and secondary fibers. Where primary fiber leads to optical power loss through bending loss and secondary fiber couples the optical power through phase coupling. The sensor design involves the primary fiber winding on the supportive cylindrical tube to make the sensor helical structure. The winding of the primary fiber makes the eleven bend loops, which are considered as the sensing points. Based on the bend loss theory, each bend loop leads variable amounts of optical power loss. To detect the vibrating motion, the secondary fiber is aligned perpendicularly with the helical structure. Combined primary and secondary fibers generate the proposed vibration sensor. In the experimental setup, the vibration motion continually varies the position of secondary fiber with helical structured fiber to couple variable optical power. The variation in the optical power coupling intensity indicates the vibration motion. The results showed that the proposed sensor design demonstrated its capability to detect the vibration repetitively and different ranges of vibrations effectively. Furthermore, software limitations impose constraints on sampling rates, restricting the proposed sensor's ability to exploit the sensor's high-frequency detection potential fully. Despite this, we have successfully reported the detection of vibrations up to 10 Hz, highlighting the sensor's substantial promise for applications requiring precise vibration monitoring within this frequency range.