Origami-Inspired Structure with Pneumatic-Induced Variable Stiffness for Multi-DOF Force-Sensing

Abstract

With the emerging need for human–machine interactions, multi-modal sensory interaction is gradually pursued rather than satisfying common perception forms (visual or auditory), so developing flexible, adaptive, and stiffness-variable force-sensing devices is the key to further promoting human–machine fusion. However, current sensor sensitivity is fixed and nonadjustable after fabrication, limiting further development. To solve this problem, we propose an origami-inspired structure to achieve multiple degrees of freedom (DoFs) motions with variable stiffness for force-sensing, which combines the ductility and flexibility of origami structures. In combination with the pneumatic actuation, the structure can achieve and adapt the compression, pitch, roll, diagonal, and array motions (five motion modes), which significantly increase the force adaptability and sensing diversity. To achieve closed-loop control and avoid excessive gas injection, the ultra-flexible microfiber sensor is designed and seamlessly embedded with an approximately linear sensitivity of ∼0.35 Ω/kPa at a relative pressure of 0–100 kPa, and an exponential sensitivity at a relative pressure of 100–350 kPa, which can render this device capable of working under various conditions. The final calibration experiment demonstrates that the pre-pressure value can affect the sensor’s sensitivity. With the increasing pre-pressure of 65–95 kPa, the average sensitivity curve shifts rightwards around 9 N intervals, which highly increases the force-sensing capability towards the range of 0–2 N. When the pre-pressure is at the relatively extreme air pressure of 100 kPa, the force sensitivity value is around 11.6 Ω/N. Therefore, our proposed design (which has a low fabrication cost, high integration level, and a suitable sensing range) shows great potential for applications in flexible force-sensing development.

Origami-Inspired Haptics: A Literature Review

“…• Molding: Much like lamination, this process involves making a mold that can accept various materials to create a part that has a mixture of properties. The mold itself can be made from inexpensive processes like 3D printing, and the mold can accept a wide range of materials from silicon to ethylene-vinyl acetate copolymer (EVA) [39], and even cardboard [40]. The advantage of this process is that it is cost-effective and easily executable without specialized equipment, while being able to make a material that combines properties from the original sub-materials.…”

3D Electronic Sensors for Bio‐Interfaced Electronics and Soft Robotics

“…The complex configurations and overall shapes of 2D materials, hinges, bonding sites, and cut patterns dictate the features of origami-and kirigami-inspired 3D structures. [109][110][111] Highly complex and on-demand shapes can be developed using origami and kirigami techniques. [109][110][111] The degree of complexity of these structures is higher than that of the structures formed following folding and buckling techniques.…”

“…[109][110][111] Highly complex and on-demand shapes can be developed using origami and kirigami techniques. [109][110][111] The degree of complexity of these structures is higher than that of the structures formed following folding and buckling techniques. Research works on origami-and kirigami-based structures focus on two directions: 1) The enhancement of stability of complex 3D shapes and 2) achieving high-level design complexity.…”

Dual‐Stroke Soft Peltier Pouch Motor Based on Pipeless Thermo‐Pneumatic Actuation

“…[5][6][7][8] Therefore, compared to traditional rigid-body robotics, soft robotics shows excellent potential for various application scenes, including the medical field, search and rescue detection, industry manipulation, educational demonstration, etc. [9][10][11][12][13][14][15] It is worth mentioning that soft actuators play an essential role in promoting soft robotics development. [16][17][18] Soft pneumatic actuators typically mimic the structure of human muscle units, i.e., bionic artificial muscles, which can realize expansion and deflation through inner pressure; meanwhile, specific constraints are applied to the structure to achieve linear and angular motion.…”

“…[ 5–8 ] Therefore, compared to traditional rigid‐body robotics, soft robotics shows excellent potential for various application scenes, including the medical field, search and rescue detection, industry manipulation, educational demonstration, etc. [ 9–15 ]…”