Zhenkun Li

Abstract Tactile sensing technology is crucial for soft grippers. Soft grippers equipped with intelligent tactile sensing systems based on various sensors can interact safely with the unstructured environments and obtain precise properties of objects (e.g., size and shape). It is essential to develop state‐of‐the‐art sensing technologies for soft grippers to handle different grasping tasks. In this review, the development of tactile sensing techniques for robotic hands is first introduced. Then, the principles and structures of different types of sensors normally adopted in soft grippers, including capacitive tactile sensors, piezoresistive tactile sensors, piezoelectric tactile sensors, fiber Bragg grating (FBG) sensors, vision‐based tactile sensors, triboelectric tactile sensors, and other advanced sensors developed recently are briefly presented. Furthermore, sensing modalities and methodologies for soft grippers are also described in aspects of force measurement, perception of object properties, slip detection, and fusion of perception. The application scenarios of soft grippers are also summarized based on these advanced sensing technologies. Finally, the challenges of tactile sensing technologies for soft grippers that need to be tackled are discussed and perspectives in addressing these challenges are pointed out.

The size-dependent elasticity of a series of nickel cantilever microbeams was investigated experimentally for the first time. The experimental results revealed that the dimensionless natural frequencies of the cantilever microbeams increase to about 2.1 times with the beam thickness decreasing from 15 to 2.1 μm. Furthermore, based on the strain gradient elasticity theory (SGT) and by using the differential quadrature method (DQM) and the least square method (LSM), the experimental results were interpreted and the material length scale parameters in the scale of micron in elastic range were obtained. This investigation will be useful and helpful for the theoretical and numerical simulation of micro-structures and important for the design of the MEMS/NEMS.

Abstract Soft robots have recently attracted increasing interest due to their advantages in durability, flexibility, and deformability, which enable them to adapt to unstructured environments and perform various complex tasks. Perception is crucial for soft robots. To better mimic biological systems, sensors need to be integrated into soft robotic systems to obtain both proprioceptive and external perception for effective usage. This review summarizes the latest advancements in flexible sensing feedback technologies for soft robotic applications. It begins with an introduction to the development of various flexible sensors for soft robots, followed by an in‐depth exploration of smart materials and advanced manufacturing methods. A detailed description of flexible sensing modalities and methodologies is also included in the review to illustrate the continuous breakthrough of the technology. In addition, the applications of soft robots based on these advanced sensing technologies are concluded as well. The challenges of flexible sensing technologies for soft robots and promising solutions are finally discussed and analyzed to provide a prospect for future development. By examining the recent advances in intelligent flexible sensing technologies, this review is dedicated to highlighting the potential of soft robotics and motivating innovation within the field.