Force and strain sensors made of soft materials enable robots to interact intelligently with their surroundings. Capacitive sensing is widely adopted thanks to its low power consumption, fast response, and facile fabrication. Capacitive sensors are, however, susceptible to electromagnetic interference and proximity effects and thus require electrical shielding. Shielding has not been previously implemented in soft capacitive sensors due to the parasitic capacitance between the shield and sensing electrodes, which changes when the sensor is deformed. We address this crucial challenge by patterning the central sensing elastomer layer to control its compressibility. One design uses an ultrasoft silicone foam, and the other includes microchannels filled with liquid metal and air. The force resolution is sub-mN both in normal and shear directions, yet the sensor withstands large forces (>20 N), demonstrating a wide dynamic range. Performance is unaffected by nearby high DC and AC electric fields and even electric sparks.

Nature has exploited softness and compliance in many different forms, from large cephalopods to microbial bacteria and algae. In all these cases, large body deformations are used for both object manipulation and locomotion. The great potential of soft robotics is to capture and replicate these capabilities in controllable robotic form. This letter presents the design of a bioinspired actuator capable of achieving a large volumetric change. Inspired by the changes in body shape seen in the euglena Eutreptiella spirogyra during its characteristic locomotion, a novel soft pneumatic actuator has been designed that exploits the hyperelastic properties of elastomers. We call this the hyperelastic bellows (HEB) actuator. The result is a structure that works under both positive and negative pressure to achieve euglenoid-like multimodal actuation. Axial expansion of 450% and a radial expansion of 80% have been observed, along with a volumetric change of 300 times. Furthermore, the design of a segmented robot with multiple chambers is presented, which demonstrates several of the characteristic shapes adopted by the euglenoid in its locomotion cycle. This letter shows the potential of this new soft actuation mechanism to realise biomimetic soft robotics with giant shape changes.

Upper limb robotic prosthetic devices currently lack adequate sensory feedback, contributing to a high rejection rate. Incorporating affective sensory feedback into these devices reduces phantom limb pain and increases control and acceptance. To address the lack of sensory feedback we present the B:Ionic glove, wearable over a robotic hand which contains sensing, computation and actuation on board. It uses shape memory alloy (SMA) actuators integrated into an armband to gently squeeze the user's arm when pressure is sensed in novel electro-fluidic fingertip sensors and decoded through soft matter logic. We found that a circular electro-fluidic sensor cavity generated the most sensitive fingertip sensor and considered a computational configuration to convey different information from robot to user. A user study was conducted to characterise the tactile interaction capabilities of the device. No significant difference was found between the skin sensitivity threshold of participants' lower and upper arm. They found it easier to distinguish stimulation locations than strengths. Finally, we demonstrate a proof-of-concept of the complete device, illustrating how it could be used to grip an object, solely from the affective tactile feedback provided by the B:Ionic glove. The B:Ionic glove is a step towards the integration of natural, soft sensory feedback into robotic prosthetic devices.

This paper presents the design of a planar, low profile, multi-directional soft crawling robot. The robot combines soft electroactive polymer actuators with compliant electroadhesive feet. A theoretical model of a multi-sector dielectric elastomer actuator is presented. The relation between actuator stroke and blocking force is experimentally validated. Electrostatic adhesion is employed to provide traction between the feet of the robot and the crawling surface. Shear force is experimentally determined and forces up to 3N have been achieved with the current pad design. A 2D multi-directional gait is demonstrated with the robot prototype. Speeds up to 12mm/s (0.1 body-lengths/s) have been observed. The robot has the potential to move on a variety of surfaces and across gradients, a useful ability in scenarios involving exploration.

Swimming is employed as a form of locomotion by many organisms in nature across a wide range of scales. Varied strategies of shape change are employed to achieve fluidic propulsion at different scales due to changes in hydrodynamics. In the case of microorganisms, the small mass, low Reynolds number and dominance of viscous forces in the medium, requires a change in shape that is non-invariant under time reversal to achieve movement. The Euglena family of unicellular flagellates evolved a characteristic type of locomotion called euglenoid movement to overcome this challenge, wherein the body undergoes a giant change in shape. It is believed that these large deformations enable the organism to move through viscous fluids and tiny spaces. The ability to drastically change the shape of the body is particularly attractive in robots designed to move through constrained spaces and cluttered environments such as through the human body for invasive medical procedures or through collapsed rubble in search of survivors. Inspired by the euglenoids, we present the design of EuMoBot, a multi-segment soft robot that replicates large body deformations to achieve locomotion. Two robots have been fabricated at different sizes operating with a constant internal volume, which exploit hyperelasticity of fluid-filled elastomeric chambers to replicate the motion of euglenoids. The smaller robot moves at a speed of body lengths per cycle (20 mm min ⁻¹ or 2.2 cycles min ⁻¹ ) while the larger one attains a speed of body lengths per cycle (4.5 mm min ⁻¹ or 0.4 cycles min ⁻¹ ). We show the potential for biomimetic soft robots employing shape change to both replicate biological motion and act as a tool for studying it. In addition, we present a quantitative method based on elliptic Fourier descriptors to characterize and compare the shape of the robot with that of its biological counterpart. Our results show a similarity in shape of 85% and indicate that this method can be applied to understand the evolution of shape in other nonlinear, dynamic soft robots where a model for the shape does not exist.