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

Abstract

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.

Biomechanics in Soft Mechanical Sensing: From Natural Case Studies to the Artificial World

“…A number of artificial whiskers have a straight cylindrical shape [85,96,108] (Figure 5E). Indeed, this particular shape increases the reachable space of the whisker compared to the typical natural shape [99].…”

“…( D ) Sensor with array of cilia using magnetoimpedance (reprinted from [84] by permission of John Wiley & Sons, Inc.). ( E ) Artificial whisker with straight cylindrical shape (reproduced from [108]. The publisher for this copyrighted material is Mary Ann Liebert, Inc. publishers).…”

A Soft Material Flow Sensor for Micro Air Vehicles

“…Unlike sensors consisting of stiff materials, soft piezoresistive sensors can be used on skin to measure strain [10][11][12] or pressure. 13,14 These types of sensors have been made possible through the development of new, highly deformable, electrically conductive materials, 15,16 the most common variants of which are aggregates consisting of conductive particles (e.g., silver nanowires [AgNWs], [17][18][19][20][21][22] silver microparticles, 23 graphene, 14,24,25 or carbon nanotubes 11,12,14 ) interspersed within a polymeric binding agent, such as polydimethylsiloxane (PDMS) or polyimide. While these composites derive their electrical conductivity and piezoresistivity from the contact and tunneling between the particulates, 23 the mechanical properties of the composites are determined mainly by the polymer, allowing them to support exceptionally large strains compared with pure metals (e on the order of 1).…”

“…[29][30][31][32][33] Whiskers are another source of inspiration stemming from biology. 24,29 In addition to velocity, similar cantilever beam-like sensors have been used to measure wall shear stress. [34][35][36] While these sensors rely on soft materials to achieve a high degree of sensitivity, this often comes at the expense of temporal bandwidth.…”

Tooth-Inspired Tactile Sensor for Detection of Multidirectional Force

“…Rather, in this type of sensor, force applied to the sensor’s moveable part allows the movement of said part to trigger the sensing elements, like the strain gauges, attached to it. For example, a whisker sensor for underwater induced vortex detection [27], which has quite a similar design with our proposed sensor, was built using three-dimensional printing technology, with a diameter of 8 mm and length of 160 mm. For MIS application, a small-scale sensor inspired by a hair cell was made, with a diameter of only 420 μm [28], a detectable shear force range below 5 mN, and a post’s maximum displacement of only 15 μm.…”