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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

The transformation kinetics formulation is the principal factor underlying the constitutive model of shape memory alloys (SMAs). Therefore, the transformation kinetics formulation, which is applicable to any status of stress and temperature, is essential for predicting the material behavior of SMAs. In this work we show that the transformation kinetics of the original Brinson model, which is the most widely used one-dimensional model, has shortcomings in the case where temperature decreases at low temperature (T<Ms). In addition, we propose a modified transformation kinetics formula that can be used for dual transformation conditions. The martensite transformation kinetics is modified so that the transformation from austenite into temperature-induced martensite, due to the decrease in temperature, is coupled with a transformation from austenite or temperature-induced martensite into stress-induced martensite, due to the increase in stress. Through this modification, the suggested formulation can properly describe the behavior of martensite fractions in the dual transformation region.

https://iopscience.iop.org/article/10.1088/0964-1726/16/1/N01/pdf

Implementation strategy for the dual transformation region in the Brinson SMA constitutive model

The mechanical characteristics of smart composite structures with embedded optical fiber sensors

Thermal buckling and postbuckling analysis of a laminated composite beam with embedded SMA actuators

Energy absorption capability and bending collapse behavior of an aluminum (Al)/carbon fiber reinforced plastic (CFRP) short square hollow section (SHS) beam were investigated under transverse quasi-static loading. The Al SHS beam was reinforced by CFRP, and the specimen was co-cured via an autoclave curing process. Three-point bending test was performed with five different lay-up sequences and three different laminate thicknesses. Stable bending collapse accompanying plastic hinge was observed in all specimens. Individual bending collapse behaviors were different depending on the lay-up sequences. The specific energy absorbed (SEA) was improved by up to 29.6% in the Al/CFRP SHS beam specimen with a [0/+45°/90°/−45°]n lay-up sequence and laminate thickness of 1.168 mm (thickness ratio of Al: CFRP = 1: 0.87, 8 plies of prepreg) compared to the Al SHS beam. The SEA was not related with damage area of the Al/CFRP SHS beam. Finite element analysis and theoretical analysis based on Kecman’s model were performed to investigate the effect of reinforcement by CFRP on the Al SHS beam.

Characteristics of aluminum/CFRP short square hollow section beam under transverse quasi-static loading

Compliant joints composed of slit tubes or springs are commonly utilized for steerable endoscopes and catheters. Because this type of joint is actuated by means of its elasticity, it is difficult to bend it with a small radius of curvature. In order to overcome this problem, a hyper-redundant Pulleyless Rolling joint with Elastic Fixtures (PREF joint) is proposed. To enable miniaturization, the PREF joint does not have a pulley, and the rolling contact motion aids the actuation cables to maintain the tension. The elastic fixtures guarantee a stable rolling motion at the center of the rolling surfaces. In this paper, the fundamental characteristics for the unit and the hyper-redundant PREF joints are presented. Moreover, design considerations are proposed for the PREF joint including the rolling tooth shape, structure of the elastic fixtures, and cable actuation method. The validity of the design is verified using finite-element analysis and a 10 mm diameter prototype composed of 12 units of PREF joints for a 1 degree-of-freedom motion. As a result, the 55 mm long joint can be bent up to ±180° with low actuation tension. The presented guidelines will assist in the development of various steerable instruments for medical applications.

Jung-Ju Lee

Papers

Implementation strategy for the dual transformation region in the Brinson SMA constitutive model

The mechanical characteristics of smart composite structures with embedded optical fiber sensors

Thermal buckling and postbuckling analysis of a laminated composite beam with embedded SMA actuators

Characteristics of aluminum/CFRP short square hollow section beam under transverse quasi-static loading

Design Considerations for a Hyper-Redundant Pulleyless Rolling Joint With Elastic Fixtures