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American Society for Testing and Materials

Human skin is a remarkable organ. It consists of an integrated, stretchable network of sensors that relay information about tactile and thermal stimuli to the brain, allowing us to maneuver within our environment safely and effectively. Interest in large-area networks of electronic devices inspired by human skin is motivated by the promise of creating autonomous intelligent robots and biomimetic prosthetics, among other applications. The development of electronic networks comprised of flexible, stretchable, and robust devices that are compatible with large-area implementation and integrated with multiple functionalities is a testament to the progress in developing an electronic skin (e-skin) akin to human skin. E-skins are already capable of providing augmented performance over their organic counterpart, both in superior spatial resolution and thermal sensitivity. They could be further improved through the incorporation of additional functionalities (e.g., chemical and biological sensing) and desired properties (e.g., biodegradability and self-powering). Continued rapid progress in this area is promising for the development of a fully integrated e-skin in the near future.

25th Anniversary Article: The Evolution of Electronic Skin (E-Skin): A Brief History, Design Considerations, and Recent Progress

Starting from human ?sense of touch,? this paper reviews the state of tactile sensing in robotics. The physiology, coding, and transferring tactile data and perceptual importance of the ?sense of touch? in humans are discussed. Following this, a number of design hints derived for robotic tactile sensing are presented. Various technologies and transduction methods used to improve the touch sense capability of robots are presented. Tactile sensing, focused to fingertips and hands until past decade or so, has now been extended to whole body, even though many issues remain open. Trend and methods to develop tactile sensing arrays for various body sites are presented. Finally, various system issues that keep tactile sensing away from widespread utility are discussed.

Tactile Sensing—From Humans to Humanoids

Advances in soft robotics, materials science, and stretchable electronics have enabled rapid progress in soft grippers. Here, a critical overview of soft robotic grippers is presented, covering different material sets, physical principles, and device architectures. Soft gripping can be categorized into three technologies, enabling grasping by: a) actuation, b) controlled stiffness, and c) controlled adhesion. A comprehensive review of each type is presented. Compared to rigid grippers, end-effectors fabricated from flexible and soft components can often grasp or manipulate a larger variety of objects. Such grippers are an example of morphological computation, where control complexity is greatly reduced by material softness and mechanical compliance. Advanced materials and soft components, in particular silicone elastomers, shape memory materials, and active polymers and gels, are increasingly investigated for the design of lighter, simpler, and more universal grippers, using the inherent functionality of the materials. Embedding stretchable distributed sensors in or on soft grippers greatly enhances the ways in which the grippers interact with objects. Challenges for soft grippers include miniaturization, robustness, speed, integration of sensing, and control. Improved materials, processing methods, and sensing play an important role in future research.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adma.201707035

Soft Robotic Grippers.

This paper provides a broad overview of medical robot systems used in surgery. After introducing basic concepts of computer-integrated surgery, surgical CAD/CAM, and surgical assistants, it discusses some of the major design issues particular to medical robots. It then illustrates these issues and the broader themes introduced earlier with examples of current surgical CAD/CAM and surgical assistant systems. Finally, it provides a brief synopsis of current research challenges and closes with a few thoughts on the research/industry/clinician teamwork that is essential for progress in the field.

/pdf/medical-robotics-in-computer-integrated-surgery-551rsaf1dd.pdf

Medical robotics in computer-integrated surgery

Mechanical behavior, such as tensile and fatigue strength, of the optical fiber sensor embedded within the composite laminate was investigated. Tensile and fatigue tests were performed to evaluate the static and fatigue characteristics of optical fibers embedded within three types of laminated composite specimens, [06/OF/06]T, [02/904/OF/904/02]T and [03/903/OF/903/03]T. The initiation of damage and fracture of the optical fiber were detected by observation of the intensity drop-off of laser signal transmitted through the optical fiber during test. Experimental results showed that the fatigue strength of optical fiber embedded within the cross-ply laminate is much lower than the fatigue strength of optical fiber within the unidirectional ply laminate. It was also found that the optical fiber embedded within unidirectional ply laminate fractured due to the fatigue damage accumulation of internal defects of optical fiber itself. However the optical fiber embedded within the cross-ply laminate fractured due to the growth of transverse matrix crack of host composite laminate.

The mechanical behavior of optical fiber sensor embedded within the composite laminate

In this paper, the thermal buckling and postbuckling behaviours of a composite beam with embedded shape memory alloy (SMA) wires are investigated experimentally and analytically. For the purpose of enhancing the critical buckling temperature and reduction of the lateral deflection on thermal buckling and postbuckling, the characteristics of thermal buckling are investigated through the use of the shape recovery force. The results of thermal buckling tests using uniformly heated and clamped composite beam specimens with embedded SMA wire actuators are discussed. The temperature-load-deflection behaviour records present quantitatively how the shape recovery force affects the thermal buckling behaviour. For this experiment, we considered the initial geometric imperfections, the slenderness ratio of the beam and the embedding position of the SMA wire actuators. The experimental results show that the shape recovery force reduces the thermal expansion of the composite laminated beam. This results in an increase...

Thermal Buckling of Laminated Composite Beams with Embedded Shape Memory Alloy Actuators

The effect of annealing temperatures on the thermomechanical behavior of NiTi in terms of transformation temperatures, mechanical properties, two-way shape memory strain, and two-way recovery stress was investigated experimentally to develop a NiTi tubular actuator with high two-way recovery force. Five tubular specimens were used to obtain the two-way shape memory strain and two-way recovery stress by varying heat treatment conditions. Annealing heat-treated temperatures were 400°C, 500°C, 600°C, 700°C, and 800°C. A two-way shape memory effect was introduced in the shape memory alloy tube by thermomechanical treatment after annealing heat treatment. According to the results, the two-way strain induced by shape memory cycling was independent of the annealing temperature. However, the two-way recovery stress generated by the two-way strain depended on the annealing temperature, even though the values of the two-way strain were similar in all specimens. Considering all heat treatment results, we concluded t...

Effect of heat treatment on the two-way recovery stress of tube-shaped NiTi

Conventional interferometric optical fiber sensors, including the extrinsic Fabry-Perot interferometric (EFPI) optical fiber sensor, have the drawback of ambiguous measurement directions and direction changes, because their signal processing using only fringe counting cannot present measurement direction information, such as tension/compression of strain or increment/decrement of temperature. An EFPI optical fiber sensor constructed with a transmission-type structure (TEFPI optical fiber sensor) can successfully compensate for this problem. However, it has low interferometric fringe visibility and requires somewhat sophisticated signal processing to detect the measurement direction changes. In this research, a hybrid EFPI optical fiber sensor is presented from which transmission-type and reflection-type sensor signals can be simultaneously acquired. The linear combination of the actual transmission-type and reflection-type signals is shown to have a shifted phase from the reflection-type signal according to measurement directions, and thus the phase behavior of lead/lag can present the measurement direction information. Because the hybrid sensor uses separated signals for the measurement quantity and direction, its signal processing is more robust than that of the TEFPI sensor. The sensor and signal processing algorithm were verified with the strain measurement experiments.

Phase-shifted transmission/reflection-type hybrid extrinsic Fabry-Perot interferometric optical fiber sensors

This paper describes the system design and the structural design to evaluate the tactile sensor using the microbending fiber optic (MBFO) sensors. The small light emitted diode (LED) and charge coupled device (CCD) are used as a single light source and a light detector for the bundle of optical fibers respectively. And the structure of this type tactile sensor which is composed of crossed fibers in the silicone rubber is very simple. And the tactile sensor element using MBFO sensor is fabricated and the performance of this sensor is evaluated.

Jung-Ju Lee

Papers

The mechanical behavior of optical fiber sensor embedded within the composite laminate

Thermal Buckling of Laminated Composite Beams with Embedded Shape Memory Alloy Actuators

Effect of heat treatment on the two-way recovery stress of tube-shaped NiTi

Phase-shifted transmission/reflection-type hybrid extrinsic Fabry-Perot interferometric optical fiber sensors

System Design and Evaluation of the Robot Tactile Sensor Using the Microbending Fiber Optic Sensors