Multifunctional Self‐Powered E‐Skin with Tactile Sensing and Visual Warning for Detecting Robot Safety

Abstract

and positions between the robots and the interacted objects. [6] Thus, various kinds of the pressure sensors have been designed and applied as different force sensing interfaces. [7,8] Although the pressure sensors are attracting great attention in robot field, the limited sensing function, rigid structure and complicated back-end data processing still raise the requirements of further advancement in the robot safety detection. Flexible electronic skin (e-skin) has been widely applied in wearable devices, artificial prosthetics, health monitoring, and smart robots as it can mimic human skin functions and convert the external stimuli into different output signals through various sensors. [9-12] Among them, tactile e-skin is drawing the attention, including human-computer interfaces, medical and security systems. [13-16] Generally, the tactile sensors based on capacitive, [17,18] piezoelectric, [19-21] resistive, [22-24] and optical [25] mechanisms rely on the deformation produced by the interaction between the sensing unit and the object. Thus, the tactile sensor will occasionally generate the unstable and insensitive signals and lead to poor detection for very weak interactions. Meanwhile, the tactile sensors often require the external power source to sense the environmental stimuli. In addition, it is noted that the reported tactile sensors are mainly focusing on the tactile sensing without the direct visualization capability. The skin of specific animal species has extra functions that can change their colors when they are activated by external stimuli. Both vertebrates and invertebrates use various strategies for visualization and camouflage. For example, Chameleons can prey, camouflage protection, and even communicate through the ability of color changing. [26] Inspired by this, it is also possible to mimic the color conversion function of chameleons through mechanical or electronic equipment. [27-30] Whitesides and his colleague reported a soft machine with a microfluidic channel that could be filled or rinsed by pumping a colored liquid. [31] Rogers's team fabricated an adaptive optoelectronic camouflage system that used a bright-colored composite, producing a black-and-white pattern to match the surrounding environment. [32] A soft material system presented by Wang et al. produced voltage-controlled on-demand fluorescent patterns which could be modulated to display a variety of geometries. [33] However, these mentioned devices can only

Biocompatible Multifunctional E-Skins with Excellent Self-Healing Ability Enabled by Clean and Scalable Fabrication

“…With the development of electronic technology, multifarious sensors have been integrated into our daily clothing and accessories, such as watches, glasses and bands, to facilitate effective and convenient real-time information collection. As one of the most ideal forms of future wearable electronic devices, electronic skins (e-skins), which exhibit an outstanding potential in the fields of health monitoring systems [1,2], human-machine interaction [3,4], artificial intelligence [5,6] and robotics [7,8], have drawn much attention in recent decades. When sensors are applied in e-skins, new demands occur.…”

Review: Sensors for Biosignal/Health Monitoring in Electronic Skin

“…TENG-based sensors, which comprise porous nanomaterials and are capable of energy harvesting, have shown good sensitivity and stretchability. Capacitive sensors using MXene have self-healing qualities and elasticity suitable for use in E-skin, but research into the high elasticity and durability of multifunctional sensors is needed [ 270 , 271 , 272 , 273 ]. Additionally, E-skin, which has the property of allowing air permeation [ 258 ], biocompatibility [ 19 ], and biodegradability [ 274 ], is also being actively studied.…”

Review of Robot Skin: A Potential Enabler for Safe Collaboration, Immersive Teleoperation, and Affective Interaction of Future Collaborative Robots

“…The sensory information perceived by robot skin can be reflected in different forms, e.g., visual and haptic signals, to give human operators complete immersion. For example, robot skin integrated with visual feedback functions, such as color-changing and light-emitting, can convert the sensory information into visual signals on-site, which can be further intuitively transmitted to a human operator [50]. The tactile information interpreted by robot skin, on the other hand, can be directly processed, transferred, and then represented as haptic signals by the haptic actuators interacting with a human operator [51].…”

“…As in humans, tactile sensing in cobots helps in understanding the contact interaction behaviors (e.g., shape, slip, softness, and roughness-smoothness) of a real-world object, making host cobots capable of detecting pressure, force, vibration, and thermal stimuli [12], [44], [59]. In addition to the above perceptual functionalities, robot skin will integrate more and more advanced functional actuators to provide sensory feedback in various modalities, such as vibrotactile and visual feedback for enhancing the user-interactivity of cobots [50], [60], or to actively control its specific properties, e.g., extending sensitivity by altering stiffness for improving the adaptability of cobots to the dynamic environment [61]. In addition to the above sensing and actuation functionalities, robot skin is also expected to be capable of suppling energy for both skin system and cobots.…”

“…The electronic skin can detect notable changes in electrical signals in the low-pressure region (below 60 kilopascals) and emit bright luminescence in the high-pressure region (above 60 kilopascals), which, respectively, imitates the functions of the mechanoreceptors (i.e., tactile sensing) and nociceptors (i.e., pain warning) in the biological skin. Wang et al [50] also reported an electronic skin with tactile sensing and visual warning for detecting robot safety. The electronic skin was applied to a cobot body and could simultaneously issue the colors varying from light green to dark blue according to the applied external force.…”