Bioinspired Microsphere-Embedded Adhesive Architectures for an Electrothermally Actuating Transport Device of Dry/Wet Pliable Surfaces

Abstract

For highly conformable and universal transport devices, bioinspired dry adhesion systems with reversible molecular attractions (e.g., van der Waals forces, capillarity, or suction stress) between the engaged surfaces have recently become favorable for various dry/wet processes in flexible devices and medical applications. In addition, many efforts have been made for switchable attachments of such adhesives by employing costly sophisticated systems such as mechanically deformable chucks, UVradiating components, or fluidic channels. In this work, we propose a simple electrothermally actuating transport device based on an octopus-inspired microsphereembedded sucker (OMS). The adhesive with microsphere-embedded suckers offers enhanced adhesion on dry/wet surfaces, in accordance with investigation of the geometric and materials parameters of the novel suction architecture for maximizing adhesion interactions. Inspired by muscle actuation of octopus tentacles, we laminate the electrothermally reactive poly(3,4-ethylenedioxy thiophene):poly(styrenesulfonic acid) (PEDOT:PSS) layer on the backside of the OMS adhesive patch. By controlling inputs of electrical energy, our assembled actuator may actively expand and contract reversibly to induce switchable attachments and detachments. Our bioinspired device can be integrated onto a robotic arm to attach and release against dry/wet flexible thin objects.

Stimuli-responsive temporary adhesives: enabling debonding on demand through strategic molecular design

“…Numerous gecko-inspired synthetic adhesives employ a force-sensitive peeling mechanism to achieve debonding. [219][220][221][222][223][224][225][226] While many of these materials rely on light or heat to induce the peeling behavior, it is the driving force of that peeling motion that causes debonding. In a representative example, Zhou and coworkers utilized a poly(acrylamideisopropyl acrylamide-acrylic acid) hydrogel coupled with a PDMS micropillar array to achieve force-sensitive bonding and debonding (Fig.…”

Low‐Voltage Soft Actuators for Interactive Human–Machine Interfaces

“…Commonly utilized electrical conductive layers are made of metals (e.g., Au, [166,167] Ag nanowires [AgNWs], [168] Ni-Cr wires [169] ), carbons (e.g., CNTs, [138] graphene, [170] and carbon fibers [171] ), MXenes (e.g., Ti 3 C 2 T x [172,173] ), conductive polymers (e.g., PEDOT:PSS [174] ), or conductive composites (e.g., AgNW/polydimethylsiloxane [PDMS], [175] Ag/graphene/ silicon rubber, [145] and Cu/Ni-coated fabric, [176] CNT/chitosan, [140] MXene/cellulose nanofiber, [173] PEDOT:PSS/paper, [19] AgNW/ PEDOT:PSS/paper [177] ). Insulating films are generally made of semicrystalline and elastomer polymers with either a low TEC (as the passive layer) or a high TEC (as the active layer), e.g., polyimide (PI), [167,169,174] polyethylene terephthalate (PET), [178] SU-8, [166] cellulose, [177] polycarbonate (PC), [173] polyethylene (PE), [168] polypropylene (PP), [176,177] PVC, [168] PDMS, [138,139,179] and liquid crystal elastomer (LCE). [167,169,180] As compared with semicrystalline polymers, elastomers generally show higher TECs and may generate higher strains/displacements but possibly lower stresses/forces.…”

“…Specially designed microgrippers based on ETAs can be fabricated by microfabrication techniques and were used to manipulate nanoscale/microscale objects such as cells and characterize mechanical performance of nanomaterials. [193,194] Macroscale soft grippers based on ETAs are easier to be fabricated in various configurations (e.g., with multiple arms or suckers) for manipulating small/fragile/sensitive objects, [169,174] and more functionalities such as sensing can be integrated with the ETA to produce intelligent interactive grippers. [180,184] A touch-triggered gripper/artificial flytrap using a self-sensing PDMS/liquid metal/ LCE ETA (Figure 11a) was made by rationally designed liquid metal circuit layer functioned as the electrical heater and mechanosensor simultaneously.…”

Applications of Bioinspired Reversible Dry and Wet Adhesives: A Review

“…In addition, photothermal polymers were adapted to micropatterned soft grippers for a fast switchable dry adhesive, where the adhesion strength could increase up to a maximum of 2.5 times after exposure to UV light (Figure 4E) . A gripper system with an electrothermally controllable sucker was presented, which was capable of fast underwater adhesion control (Figure 4F) (Baik et al, 2021).…”