A Perspective on Miniature Soft Robotics: Actuation, Fabrication, Control, and Applications

Abstract

Soft robotics enriches the robotic functionalities by engineering soft materials and electronics toward enhanced compliance, adaptivity, and friendly human machine. This decade has witnessed extraordinary progresses and benefits in scaling down soft robotics to small scale for a wide range of potential and promising applications, including medical and surgical soft robots, wearable and rehabilitation robots, and unconstructed environments exploration. This perspective highlights recent research efforts in miniature soft robotics in a brief and comprehensive way in terms of actuation, powering, designs, fabrication, control, and applications in four sections. Section 2 discusses the key aspects of materials selection and structural designs for small‐scale tethered and untethered actuation and powering, including fluidic actuation, stimuli‐responsive actuation, and soft living biohybrid materials, as well as structural forms from 1D to 3D. Section 3 discusses the advanced manufacturing techniques at small scales for fabricating miniature soft robots, including lithography, mechanical self‐assembly, additive manufacturing, tissue engineering, and other fabrication methods. Section 4 discusses the control systems used in miniature robots, including off‐board/onboard controls and artificial intelligence‐based controls. Section 5 discusses their potential broad applications in healthcare, small‐scale objects manipulating and processing, and environmental monitoring. Finally, outlooks on the challenges and opportunities are discussed.

A differentiable actuator extends potential configurations of modular robots

“…There are some knowledge gaps in designing differentiable actuators and composing as many potential robot configurations as possible. First, smart materials and mechanical structures [39][40][41][42][43][44] are needed to provide multidimensional and efficient motion. Proper mechanical design enables actuators to respond to mechanical preloading and differentiate like MSCs.…”

Hot Fingers: Individually Addressable Graphene-Heater Actuated Liquid Crystal Grippers

“…Stimuli-responsive materials have been receiving increased attention, especially for motile devices, biomedical applications including wearables and surgical devices, dynamic surfaces, and materials for personal comfort. − Liquid crystal (LC) actuators based on LC elastomers (LCEs) or LC networks (LCNs) are prime candidate materials for use in soft-touch devices ,− and are promising alternatives to, for example, hydrogels and silicones . LCE/LCN grippers have structures which can bend due to internal disruption of the LC mesogenic order with large deflections at relatively low actuation temperatures, facilitating soft gripping without introducing damage to the object. ,− Nevertheless, soft actuators with control over individual gripper fingers are still in their infancy and often are not optimized: for example, they cannot independently actuate their fingers − or are overly complex in design. , …”