Fully 3D Printed Multi-Material Soft Bio-Inspired Whisker Sensor for Underwater-Induced Vortex Detection.

Bio-mimicking the underwater sensors has tremendous potential in soft robotics, under water exploration and human interfaces. Pinniped are semiaquatic carnivores that use their whiskers to sense food by tracking the vortices left by potential prey. To detect and track the vortices inside the water, a fully 3D printed pinniped inspired multi-material whisker sensor is fabricated and characterized. The fabricated whisker is composed of a polyurethane rod with a length-to-diameter ratio (L/d) of 20:1 with four graphene patterns (length × diameter: 60 × 0.3 mm) perpendicular to each other. The graphene patterns are further connected with output signal wires via copper tape. The displacement (∼5 mm) of the whisker rod in any direction (0-360°) causes the change in resistance [Formula: see text] because of generated tensile. The analog signals (resistance change) are digitalized by using analog to digital modules and fed to a microcontroller to detect the vortex. A virtual environment is designed such that it consists of a 3D printed fish fin, a water tank, a camera, and data loggers to study the response of fabricated whisker. The underwater sensitivity of the whisker sensor in any direction is detectable and remarkably high ([Formula: see text]% ∼1180). The mechanical reliability of the whisker sensor is tested by bending it up to 2000 cycles. The fabricated whisker's structure and material are unique, and no one has fabricated them by using cost-effective 3D printing methods earlier. This fully 3D printable flexible whisker sensor should be applicable to a wide range of soft robotic applications.

Omni Directional Multimaterial Soft Cylindrical Actuator and Its Application as a Steerable Catheter.

Soft actuators with complex range of motion lead to strong interest in applying devices like biomedical catheters and steerable soft pipe inspectors. To facilitate the use of soft actuators in devices where controlled, complex, precise, and fast motion is required, a structurally controlled Omni directional soft cylindrical actuator is fabricated in a modular way using multilayer composite of polylactic acid based conductive Graphene, shape memory polymer, shape memory alloy, and polyurethane. Multiple fabrication techniques are discussed step by step that mainly include fused deposition modeling based 3D printing, dip coating, and UV curing. A mathematical control model is used to generate patterned electrical signals for the Omni directional deformations. Characterizations like structural control, bending, recovery, path, and thermal effect are carried out with and without load (10 g) to verify the new cylindrical design concept. Finally, the application of Omni directional actuator as a steerable catheter is explored by fabricating a scaled version of carotid artery through 3D printing using a semitransparent material.