Introduction to quality engineering : designing quality into products and processes

Flexible electronics, as an emerging and exciting research field, have brought great interest to the issue of how to make flexible electronic materials that offer both durability and high performance at strained states. With the advent of on-body wearable and implantable electronics, as well as increasing demands for human-friendly intelligent soft robots, enormous effort is being expended on highly flexible functional materials, especially stretchable electrodes, by both the academic and industrial communities. Among different deformation modes, stretchability is the most demanding and challenging. This review focuses on the latest advances in stretchable transparent electrodes based on a new design strategy known as kirigami (the art of paper cutting) and investigates the recent progress on novel applications, including skin-like electronics, implantable biodegradable devices, and bioinspired soft robotics. By comparing the optoelectrical and mechanical properties of different electrode materials, some of the most important outcomes with comments on their merits and demerits are raised. Key design considerations in terms of geometries, substrates, and adhesion are also discussed, offering insights into the universal strategies for engineering stretchable electrodes regardless of the material. It is suggested that highly stretchable and biocompatible electrodes will greatly boost the development of next-generation intelligent life-like electronics.

Flexible Electronics: Stretchable Electrodes and Their Future

In the past few years, soft robotics has rapidly become an emerging research topic, opening new possibilities for addressing real-world tasks Perception can enable robots to effectively explore the unknown world, and interact safely with humans and the environment Among all extero- and proprioception modalities, the detection of mechanical cues is vital, as with living beings A variety of soft sensing technologies are available today, but there is still a gap to effectively utilize them in soft robots for practical applications Here, the developments in soft robots with mechanical sensing are summarized to provide a comprehensive understanding of the state of the art in this field Promising sensing technologies for mechanically perceptive soft robots are described, categorized, and their pros and cons are discussed Strategies for designing soft sensors and criteria to evaluate their performance are outlined from the perspective of soft robotic applications Challenges and trends in developing multimodal sensors, stretchable conductive materials and electronic interfaces, modeling techniques, and data interpretation for soft robotic sensing are highlighted The knowledge gap and promising solutions toward perceptive soft robots are discussed and analyzed to provide a perspective in this field

https://onlinelibrary.wiley.com/doi/pdf/10.1002/advs.201800541

Toward Perceptive Soft Robots: Progress and Challenges

Soft robots are often inspired from biological systems which consist of soft materials or are actuated by electrically activated materials. There are several advantages of soft robots compared to the conventional robots; safe human-machine interaction, adaptability to wearable devices, simple gripping system, and so on. Due to the unique features and advantages, soft robots have a considerable range of applications. This article reviews state-of-the-art researches on soft robots and application areas. Actuation systems for soft robots can be categorized and analyzed into three types: variable length tendon, fluidic actuation, and electro-active polymer (EAP). The deformable property of soft robots restricts the use of many conventional rigid sensors such as encoders, strain gauges, or inertial measurement units. Thus, contactless approaches for sensing and/or sensors with low modulus are preferable for soft robots. Sensors include low modulus (< 1 MPa) elastomers with liquid-phase material filled channels and are appropriate for proprioception which is determined by the degree of curvature. In control perspective, novel control idea should be developed because the conventional control techniques may be inadequate to handle soft robots. Several innovative techniques and diverse materials & fabrication methods are described in this review article. In addition, a wide range of soft robots are characterized and analyzed based on the following sub-categories; actuation, sensing, structure, control and electronics, materials, fabrication and system, and applications.

Soft robot review

Recent progress on flexible and stretchable piezoresistive strain sensors: From design to application

Gravity is omnipresent on Earth; however, humans in space, such as astronauts at the International Space Station, experience microgravity. Long-term exposure to microgravity is considered to elicit physiological changes, such as muscle atrophy, in the human body. In addition, certain types of cancer cells demonstrate inhibited proliferation under condition of time-averaged simulated microgravity (taSMG). However, the response of human Hodgkin’s lymphoma cancer cells to reduced gravity, and the associated physiological changes in these cells, have not been elucidated. In this study, the proliferation of human Hodgkin’s lymphoma cancer cells (L-540 and HDLM-2) under taSMG condition (<10−3 G, 1 G is defined as 9.8 m/s2) was studied using a 3D clinostat. Normal human dermal fibroblast (HDF) was proliferated in the same condition as a control group. For the development of 3D clinostat, two motors were used to actuate the frames. Electrical wires for power supply and communication were connected via slip ring. For symmetrical path of gravitational vector, optimal angular velocities of the motors were found using simulation results. Under the condition of taSMG implemented by the 3D clinostat, proliferation of the cells was observed for 3 days. The results indicated that proliferation of these cancer cells was significantly (p < 0.0005) inhibited under taSMG, whereas proliferation of normal HDF cells was not affected. Findings in this study could be significantly valuable in developing novel strategies for selective killing of cancer cells such as lymphoma.

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Time-averaged simulated microgravity (taSMG) inhibits proliferation of lymphoma cells, L-540 and HDLM-2, using a 3D clinostat

The treatment device for hemiplegia comprises a robot which is putted on the hemiplegic side of the body of a subject; a motion measurement unit for measuring the motion of the healthy side of the body of the subject; and a control which is connected with the robot and the motion measurement unit, wherein the control unit is configured to receive the healthy side's motion measured by the motion measurement unit and to control the robot, whereby the hemiplegic side having the robot put thereon moves in accordance with the motion of the healthy side of the body.

Treatment device for hemiplegia

A torque transfer system (TTS) that measures grip forces is developed to resolve a potential drawback of the current da Vinci robot system whose grip forces vary according to the different postures of its EndoWrist. A preliminary model of EndoWrist Inner Mechanism Model (EIMM) is also developed and validated with real grip force measurements. EndoWrist’s grip forces, posture angles, and transferred torque are measured by using TTS. The mean measured grip forces of three different EndoWrist for 27 different postures were very diverse. The EndoWrist exerted different grip forces, with a minimum of 1.84-times more and a maximum of 3.37-times more in specific posture even if the surgeon exerted the same amount of force. Using the posture angles as input and the grip forces as output, the EIMM is constructed. Then, expected grip force values obtained from EIMM are compared with actual measurements of da Vinci EndoWrist to validate the proposed model. From these results, surgeons will be beneficial with the understandings of actual grip force being applied to tissue and mechanical properties of robotic system. The EIMM could provide a baseline in designing a force-feedback system for surgical robot. These are significantly important to prevent serious injury by maintaining a proper force to tissue.

Chiwon Lee

Papers

Soft robot review

Time-averaged simulated microgravity (taSMG) inhibits proliferation of lymphoma cells, L-540 and HDLM-2, using a 3D clinostat

Treatment device for hemiplegia

A grip force model for the da Vinci end-effector to predict a compensation force

Fabrication of three-dimensional scan-to-print ear model for microtia reconstruction