Soft Pneumatic Actuator skin (SPA-skin) is a novel concept of ultra-thin (<; 1 mm) sensor embedded actuators with distributed actuation points that could cover soft bodies. This highly customizable and flexible SPA-skin is ideal for providing proprioceptive sensing by covering pre-existing structures and robots bodies. Having few limitation of the surface quality, dynamics, or shape, these mechanical attributes allow potential applications in autonomous flexible braille, active surface pattern reconfiguration, distributed actuation and sensing for tactile interface improvements. In this paper, the authors present a proof-of-concept SPA-skin. The mechanical parameters, design criteria, sensor selection, and actuator construction process are illustrated. Two control schemes, actuation mode and force sensing mode, are also demonstrated with the latest prototype.

Soft actuators made of highly elastic polymers allow novel robotic system designs, yet application-specific soft robotic systems are rarely reported. Taking notice of the characteristics of soft pneumatic actuators (SPAs) such as high customizability and low inherent stiffness, we report in this work the use of soft pneumatic actuators for a biomedical use - the development of a soft robot for rodents, aimed to provide a physical assistance during gait rehabilitation of a spinalized animal. The design requirements to perform this unconventional task are introduced. Customized soft actuators, soft joints and soft couplings for the robot are presented. Live animal experiment was performed to evaluate and show the potential of SPAs for their use in the current and future biomedical applications.

Conventional pneumatic actuators have been a popular choice due to their decent force/torque output. Nowadays, new generation of pneumatic actuator made out of highly compliant elastomers, which we call soft pneumatic actuators (SPA), are drawing increasing attention due to their ease of fabrication, high customizability and innately softness. However, there is no effective method presented to characterize and understand these actuators, such as to measure the force and torque output, range of motion and the speed of actuation. In this work, we present two types of SPAs: bending and rotary actuators. In addition, we have developed two measurement setups to characterize actuators of different geometries. The measured force/torque outputs of different actuators are presented and analyzed. Step responses to certain pressure input are presented and discussed. A simple model is presented to provide physical insight to the observed behavior of the soft actuators. This work provides the basis for designing customized SPAs with application-specific requirements.

Recently, a few water strider robots that mimic the static and dynamic key characteristics of the insect water striders have been reported in the literature. These robots either lacked mobility or was tethered to an external source of power. Using the recent findings on the supporting legs of these robots creating repulsive surface tension based lift forces, a heavier yet highly maneuverable and non-tethered water strider robot, called STRIDE, is proposed in this paper. STRIDE uses two miniature DC motors and a lithium-polymer battery that are connected to the driving circuit on-board. Optimal leg shape is manufactured by bending 0.33 mm diameter stainless steel wires with a Teflonreg coating. This 6.13 gr non-tethered robot with twelve supporting legs demonstrated a linear motion of 8.7 cm/s and a rotational motion of 0.8 rad/s. STRIDE would have potential applications in continuous water quality monitoring on lakes, dams, and other water sources and in entertainment and education in the near future.

Recent biological studies on water strider insects revealed how they maintain stability and maneuver on the surface of water. While macroscale bodies use buoyancy, these very small insects use surface tension force to balance their weight on water. This paper proposes a biologically inspired miniature robot that utilizes the unique scaling advantage of these insects. The paper focuses on understanding the physics of the interaction between the insect and the surface of water and on designing a robot that mimics their key features. Hydrophobic Teflon coated wire legs optimized to take the most advantage of the surface tension force are used to support the weight of the 1-g robot. It is shown that twelve of these legs can support up to 9.3 g of payload. A T-shape actuation mechanism with three piezoelectric unimorph actuators is designed and studied to enable controlled locomotion. Static and dynamic properties of the robot are analyzed and compared with the experimental results. The tethered robot can successfully make both linear and rotational motions. Maximum forward speed is measured to be 3 cm/s, and the rotational speed is 0.5 rad/s. This robot proposes a new way of locomotion on water surface for future robots and devices.

Recent studies on the insect water strider showed that the insect heavily relies on surface tension force to stay afloat. Inspired by this insect, water strider robots have been developed using the same locomotive principles as the insect. This paper focuses on numerically modeling the supporting legs of the insect and the robots. The rigid-leg model as well as the compliant-leg model is developed using numerical approaches, under an assumption made on the water surface breaking condition. The effect of different leg material and geometry are discussed. It is shown through simulations that four 7 cm-long Teflonreg coated compliant supporting legs with optimized shapes can lift up to 4.3 grams (0.15 g/cm), while an actual prototype carried 3.7 grams. Another prototype using twelve of these legs successfully lifted 9.3 grams. Experiments show that the analyses capture the important features of the supporting legs. The design rules proposed in this paper are useful in understanding the insect statics and also the robotic water strider supporting leg design. This study allows a heavier robot to be used for education, entertainment or environment monitoring purposes