A Review of Smart Materials in Tactile Actuators for Information Delivery

As the largest organ in the human body, the skin provides the important sensory channel for humans to receive external stimulations based on touch. By the information perceived through touch, people can feel and guess the properties of objects, like weight, temperature, textures, and motion, etc. In fact, those properties are nerve stimuli to our brain received by different kinds of receptors in the skin. Mechanical, electrical, and thermal stimuli can stimulate these receptors and cause different information to be conveyed through the nerves. Technologies for actuators to provide mechanical, electrical or thermal stimuli have been developed. These include static or vibrational actuation, electrostatic stimulation, focused ultrasound, and more. Smart materials, such as piezoelectric materials, carbon nanotubes, and shape memory alloys, play important roles in providing actuation for tactile sensation. This paper aims to review the background biological knowledge of human tactile sensing, to give an understanding of how we sense and interact with the world through the sense of touch, as well as the conventional and state-of-the-art technologies of tactile actuators for tactile feedback delivery

Micro Motion Amplifiers for Compact Out-of-Plane Actuation

Small-scale, out-of-plane actuators can enable tactile interfaces; however, achieving sufficient actuator force and displacement can require larger actuators. In this work, 2-mm2 out-of-plane microactuators were created, and were demonstrated to output up to 6.3 µm of displacement and 16 mN of blocking force at 170 V. The actuators converted in-plane force and displacement from a piezoelectric extensional actuator into out-of-plane force and displacement using robust, microelectromechanical systems (MEMS)-enabled, half-scissor amplifiers. The microscissors employed two layers of lithographically patterned SU-8 epoxy microstructures, laminated with a thin film of structural polyimide and adhesive to form compact flexural hinges that enabled the actuators’ small area. The self-aligned manufacture minimized assembly error and fabrication complexity. The scissor design dominated the actuators’ performance, and the effects of varying scissor angle, flexure thickness, and adhesive type were characterized to optimize the actuators' output. Reducing the microscissor angle yielded the highest actuator performance, as it maximized the amplification of the half-scissor's displacement and minimized scissor deformation under externally applied loads. The actuators' simultaneously large displacements and blocking forces for their size were quantified by a high displacement-blocking force product per unit area of up to 50 mN·µm/mm². For a linear force–displacement relationship, this corresponds to a work done per unit area of 25 mN·µm/mm². Keywords: microactuators; tactile actuators; piezoelectric actuators; scissor mechanism; motion amplifier; out-of-plane actuato

A Modular, Reconfigurable Microfabricated Assembly Platform for Microfluidic Transport and Multitype Cell Culture and Drug Testing

Modular microfluidics offer the opportunity to combine the precise fluid control, rapid sample processing, low sample and reagent volumes, and relatively lower cost of conventional microfluidics with the flexible reconfigurability needed to accommodate the requirements of target applications such as drug toxicity studies. However, combining the capabilities of fully adaptable modular microelectromechanical systems (MEMS) assembly with the simplicity of conventional microfluidic fabrication remains a challenge. A hybrid polydimethylsiloxane (PDMS)-molding/photolithographic process is demonstrated to rapidly fabricate LEGO®-like modular blocks. The blocks are created with different sizes that interlock via tongue-and-groove joints in the plane and stack via interference fits out of the plane. These miniature strong but reversible connections have a measured resistance to in-plane and out-of-plane forces of up to >6000× and >1000× the weight of the block itself, respectively. The LEGO®-like interference fits enable O-ring-free microfluidic connections that withstand internal fluid pressures of >120 kPa. A single layer of blocks is assembled into LEGO®-like cell culture plates, where the in vitro biocompatibility and drug toxicity to lung epithelial adenocarcinoma cells and hepatocellular carcinoma cells cultured in the modular microwells are measured. A double-layer block structure is then assembled so that a microchannel formed at the interface between layers connects two microwells. Breast tumor cells and hepatocytes cultured in the coupled wells demonstrate interwell migration as well as the simultaneous effects of a single drug on the two cell types

Electrical performance analysis of 110 kv GIS terminal extension conducting rod

As GIS terminal is in cooperation with GIS switch, the GIS terminal with 470 mm structure is usually equipped with a 757 mm structure GIS switch. In order to study the influence of the extended conductive pole on the electrical performance of GIS cable terminal, the contact resistance of the extended conductive pole is measured. The measurement results show that the contact resistance meets the requirements of conductive flow. Through finite element simulation calculation of the influence of the extended conducting rod on the GIS terminal electric field distribution, it was found that the maximum field strength of the cable terminal of the extended conducting rod increased by 2 kv/mm, which was smaller than the breakdown field strength of sulfur hexafluoride gas, and the extended conducting rod did not affect the safe and stable operation of the GIS terminal. Extend the conductive rod by finite element simulation calculation interface without air gap and 0.1 mm gap, the distribution of electric field in both cases, contact resistance conforms to the requirements under the premise, extend the conductive rod interface is 0.1 mm gap the maximum field strength of 1.4 kv/mm, less than the sulfur hexafluoride gas breakdown voltage, contact air gap does not affect the safe and stable operation of the GIS terminal

Research summary of cable channel fire extinguishing technology

Cable channel fire is an important factor affecting the safe operation and maintenance of power cables. This paper summarizes the current research situation of fire-extinguishing technology, analyzes the fire-extinguishing technology suitable for cable channel, and proposes to use S-type aerosol fire-extinguishing technology to extinguish the fire of cable channel.

Simulating urban expansion using a cloud-based cellular automata model: A case study of Jiangxia, Wuhan, China

Because of the complexity of urban systems, the dynamic process of urban expansion is filled with uncertainty. Although many studies have been done on cellular automata (CA)-based urban expansion models, the measurements of uncertainties and uncertainty propagation were commonly neglected when constructing CA models. The cloud model can express uncertainty and its propagation, and coherently integrates fuzziness and randomness as well as overcoming the limitations of fuzzy theory and the Monte Carlo method. A cloud-based CA (cloud-CA) model is presented in this paper to represent uncertainty propagation and show the dependence of simulation results on different degrees of uncertainty represented by hyper-entropy (He). We implemented the cloud-CA model and applied it on the simulation of the urban expansion in Jiangxia, Wuhan, China. After constructing the appropriate parameter settings for the cloud-CA model, a comparison of cloud-CA with the fuzzy-set-based CA (fuzzy-CA) model, and the hybrid CA model based on fuzzy set and the Monte Carlo method (FSMC-CA) was made by simulating spatial patterns of urban growth in Jiangxia from 2002 to 2007. The experiment indicated that the cloud-CA model has a better performance than the other two CA models, with higher kappa indices and figure of merit, proving the effectiveness of the cloud-CA model. © 2012.link_to_subscribed_fulltex

Research and analysis on defect detection of semi-conductive layer of high voltage cable

As a component of the Internet of things, high-voltage cables are the power supply infrastructure for the modern development of cities. The operation experience shows that the high-voltage cable has been broken down many times due to the defective operation. At present, due to the limitation of detection technology, the research on detection and identification of defects in high-voltage cables is progressing slowly. Therefore, a new DR technology based on X-ray digital imaging is proposed in this paper to realize real-time detection of defects in the semi-conductive buffer layer of high-voltage cables, and intelligent detection of DR images of high-voltage cables by using image depth processing technology to realize intelligent identification of defects in the buffer layer of power cables. The results show that using the new DR technique proposed in this paper, the accurate and intuitive DR image of high-voltage cable can be obtained quickly, and the intelligent identification of defects can be realized