Re-engineering artificial muscle with microhydraulics

Abstract

We introduce a new type of actuator, the microhydraulic stepping actuator (MSA), which borrows design and operational concepts from biological muscle and stepper motors. MSAs offer a unique combination of power, efficiency, and scalability not easily achievable on the microscale. The actuator works by integrating surface tension forces produced by electrowetting acting on scaled droplets along the length of a thin ribbon. Like muscle, MSAs have liquid and solid functional components and can displace a large fraction of their length. The 100 μm pitch MSA presented here already has an output power density of over 200 W kg − 1 , rivaling the most powerful biological muscles, due to the scaling of surface tension forces, MSA's power density grows quadratically as its dimensions are reduced.

High-performance polyvinyl chloride gel artificial muscle actuator with graphene oxide and plasticizer

“…However, this type of actuator requires high voltages (often >1 kV) because high electric fields (~100 V/µm) are necessary for actuation 9 . Microhydraulic artificial muscles have also been heavily studied and come in a variety of forms, but they are often used in applications where larger actuators are necessary (for McKibben type hydraulic actuators), or do not have as high of a force output as other artificial muscles as is the case with microhydraulic stepping actuators 10 . Recent progress has also been made into the use of liquid dielectrics in hydraulically amplified self-healing electrostatic actuators which allow for very large displacements to be obtained with a high frequency, these are very promising for some larger applications, but the voltages used can often be on the range of 10 s of kV, which is too high for many applications 11 .…”

Phototaxis Motion Behavior of a Self‐propelled Submarine‐like Water Droplet Robot in Oil Solvent

“…Unlike other inanimate machines, the self‐propelling droplet is working in liquid environment. Considerable attention has been paid on studying the interface mechanics of self‐propelling liquid droplets and their potential applications as biocompatible carriers and sensors that can be used for target drug delivery or exploring microscopical complex areas [12–18] . Since oil and water are immiscible liquids which are easy to prepare and characterize, oil‐water system, especially the self‐propelling oil droplet in water phase, is a standard model for investigating the mechanism of self‐propelling phenomenon [19–21] .…”

Novel fabrication of soft microactuators with morphological computing using soft lithography

“…Soft robotic systems have been driven by various actuation mechanisms 16,17 , such as based on variable length tendons 18 , shape memory alloys 19 , pneumatic actuator muscles (PAM) 20–22 , and flexible elastomeric actuators (FEAs), operated either pneumatically 23,24 or hydraulically 25–27 . Presently, PAMs or FEAs are the prevalent technologies driving the soft robotic actuators at centimeter or larger scales.…”