Highly Sensitive Soft Foam Sensors to Empower Robotic Systems

Abstract

Soft robots require seamless integration with sensors and actuators that are simple to manufacture at scale with low cost and minimum footprint. The sensor materials must be highly reliable, sensitive, and stable, and their mechanical features should match the sensing requirements of soft robots such as minimal response time and nonlinearity of hysteresis and relaxation. A resistive-type sensor based on the synthesis of poly(glycerol secabate) (PGS) with a foam-like structure and outstanding mechanical, electrical, and electromechanical properties is developed. These foam sensors present high sensitivity (gauge factor ≈ −9), very fast response (≤3 ms), negligible hysteresis, reliability, long lifetime (>1 200 000 cycles), and a pressure differential sensitivity of 34 Pa. They can accurately detect low and high frequency vibrations (up to 300 Hz) and small forces (200 mN) that cover the very low detection range of metallic strain gauges and the very large detection range of elastomeric strain sensors. These characteristics closely match those of the human fingertip, and hence pave the way toward tactile and compliant sensing elements embedded in prosthetic hands. Prospective applications for unexplored resistive-type sensors to meet the sensory requirements of soft robotic systems are demonstrated.

Materials, Electrical Performance, Mechanisms, Applications, and Manufacturing Approaches for Flexible Strain Sensors

“…The remote control of a robotic arm to pick up and put down the target object kept the risks away from people. Recently, a group of tactile sensors using piezoresistive foams was proposed and mounted to each finger of the 3D printed gripper, [ 212 ] the state of each sensor was displayed by virtual LED when the gripper works and releasing. Moreover, combined with the concept of “second skin” for human motor assistance raised by Eugene C. Goldfield et al, [ 213 ] those reported sensors could be widely carried forward in the field of soft robots and remote manipulation requirement.…”

Finite Element Modeling in the Design Process of 3D Printed Pneumatic Soft Actuators and Sensors

“…Soft robots demand dexterous soft actuators that can generate relatively low and high forces (i.e., controllable forces) to facilitate soft and adaptive interaction with their environments [5]. In addition, soft robots require robust flexible, stretchable, or compressive soft sensors that can sustain large deformations repeatedly over sustained periods, while providing consistent output signals [6]. Such reliable and stable sensors are essential for soft robots to develop reliable feedback control systems [7,8].…”

A Review of 3D‐Printable Soft Pneumatic Actuators and Sensors: Research Challenges and Opportunities

“…However, the integration of such sensors into soft robotic systems and devices requires multiple and laborious fabrication steps. Resistive stretchable and/or flexible strain sensors such as flex sensors, [ 54 ] conductive inks, [ 55 ] ionic conductive liquids, [12a] liquid metals, [20b,56] fabrics and textiles, [ 57 ] highly compressive, sensitive, and biodegradable foam sensors, [ 58 ] resistive 3D printable thermoplastics, [ 59 ] and ultrathin piezoresistive sensors [ 60 ] incorporated in soft and deformable 3D‐printable bodies [ 61 ] were established for soft sensing applications. Also, capacitive soft sensors that can be used as pressure sensors, [ 62 ] tactile sensors, [ 63 ] and strain sensors were developed for soft robotic systems.…”