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Soft actuator is the key component for soft robots to realize flexible motion. But the difficulty of sensing and control of soft actuators seriously restricts their application. Twisted artificial muscles (TAMs) made from together self-coiling of nylon 6,6 fiber and heating wire are potential to address this challenge due to their extremely high actuating stress and self-sensing ability. However, the together coiled twisted artificial muscles (TCTAMs) have a large self-sensing hysteresis because of the small heating area and the self-coiling process restricts their deformation stroke. Besides, the lack of accurate physical models also blocks the development of the TCTAMs. This article presents a new type of tightly wrapped twisted artificial muscles (TWTAMs) to improve the stroke and reduce the hysteresis. Compared with TCTAMs, the hysteresis of TWTAMs is reduced by 76% and the stroke is improved by 35%. Besides, a physical analytical model based on the self-sensing temperature is established and verified by experiments. This article not only provides a new type of TAMs with large stroke and low hysteresis, but also offers an accurate theoretical analysis model for the performance prediction of TWTAM. [ABSTRACT FROM AUTHOR]

Soft grippers can be used to grasp objects with various geometric surface structures or stiffness but typically encounter difficulty in providing high grasping force. Although the combination of soft grippers with adhesive technology can increase their load capacity, this approach has disadvantages of compatibility and limited application range. This article has reported a bioinspired design of a soft gripper that integrates flat dry adhesive, soft actuator, and microspine to improve the comprehensive grasping ability of the soft gripper on smooth or rough surfaces. The adhesive strength of flat dry adhesives with different thickness or cross-linking ratios was investigated to ensure that a large grasping force can be provided. Soft actuators with uniform and nonuniform cross-sectional heights were compared, and results indicated that the soft actuator with a nonuniform cross-sectional height exhibited remarkable advantages for designing the integrated gripper. A microspine–spring–shape memory alloy coil structure was designed to control the retraction and protrusion of microspine and distribute the load on rough surfaces evenly. The proposed integrated gripper with the aforementioned design can lift regularly or irregularly shaped objects with smooth or rough surfaces and provide a higher adhesive force than the nonadhesive gripper. After inserting a flexible pressure film sensor into the soft gripper, the surface property of the grasped object can be measured, which is beneficial for the selection of a suitable grasping strategy in unknown environments. The designed gripper can be used in many applications, such as in unmanned aerial vehicles, industrial manipulators, and climbing robots. [ABSTRACT FROM AUTHOR]

In this article, we demonstrate a wireless and passive physiological pressure sensing scheme that utilizes ultrasound imaging of an implantable microfluidic based pressure sensitive transducer. The transducer consists of a sub-mm scale pressure sensitive membrane that covers a reservoir filled with water and is connected to a hydrophobic micro-channel. Applied pressure onto the transducer deflects the membrane and pushes the water from the reservoir into the channel; the water's travelling distance in the channel is a function of the applied pressure, which is quantitatively measured by using a 40 MHz ultrasound imaging system. The sensor presents a linear sensitivity of 42 kPa/mm and a spatial resolution of 1.2 kPa/30 μm in the physiological range of abdominal compartment syndrome. Reliability assessments of the transducer confirm its ability to remain functional after more than 600 cycles of pressure up to 55 kPa over the course of 2 days. Ex vivo experimental results verify the practical capability of the technology to effectively measure pressures under a 15 mm thick porcine skin. It is anticipated that this technology can be applied to a broad range of implantable pressure measurement, by simply tuning the thickness of the thin polydimethylsiloxane membrane and the geometry of the reservoir. [ABSTRACT FROM AUTHOR]

Numerous soft grippers have been developed based on smart materials, pneumatic soft actuators, and underactuated compliant structures. In this article, we present a three-dimensional (3-D) printed omni-purpose soft gripper (OPSOG) that can grasp a wide variety of objects with different weights, sizes, shapes, textures, and stiffnesses. The soft gripper has a unique design that incorporates soft fingers and a suction cup that operate either separately or simultaneously to grasp specific objects. A bundle of 3-D-printable linear soft vacuum actuators (LSOVA) that generate a linear stroke upon activation is employed to drive the tendon-driven soft fingers. The support, fingers, suction cup, and actuation unit of the gripper were printed using a low-cost and open-source fused deposition modeling 3-D printer. A single LSOVA has a blocked force of 30.35 N, a rise time of 94 ms, a bandwidth of 2.81 Hz, and a lifetime of 26 120 cycles. The blocked force and stroke of the actuators are accurately predicted using finite element and analytical models. The OPSOG can grasp at least 20 different objects. The gripper has a maximum payload-to-weight ratio of 7.06, a grip force of 31.31 N, and a tip blocked force of 3.72 N. [ABSTRACT FROM AUTHOR]

The relationships among bolus formulation, engineering rheometric quantities, and peristaltic transport effects are examined in this paper. Investigation of a series of synthetic bolus materials and swallowing strategies is conducted using a novel peristaltic swallowing robot inspired by esophageal swallowing, which manifests as a benchtop rheological instrument. To determine the validity of biomimetic swallowing, manometry, a clinical technique for capturing swallowing pressure profiles is used to establish congruence between the robotic findings and those of a clinical nature. To determine the contribution of the bolus and swallowing strategy to the intraluminal pressure signature (ILPS), three parameters were varied: peristaltic wave velocity (20, 30, 40 mm \mathrms^-1 ), wavefront length (40, 50, and 60 mm) and starch thickener (Nutulis, Nutricia) concentration (25, 50, 75, 100, and 150 g \mathrmL^-1 ) were investigated. Wave velocity and starch-based bolus formulation concentration were found to exhibit the most profound changes in the intrabolus pressure signatures. The highest bolus tail pressure gradient of 0.33 kPa \mathrmmm^-1 was achieved with a 150 g \mathrmL^-1 bolus formulation being transported at 40 mm \mathrms^-1 with a wavefront length of 60 mm. In each dimension, the relationship between the parameters and features of the manometric pressure signature are found to be nonlinear owing to the shear-thinning, non-Newtonian nature of the model bolus fluid. The robotic ILPSs are synonymous with those of a clinical nature, suggesting that the swallowing robot has merit as a novel, biologically inspired, bolus investigation tool external to the human body. [ABSTRACT FROM PUBLISHER]