Advanced Materials · 2020 · 263 citations · 35 references
EngineeringBiomedical EngineeringMechanical EngineeringActuatorsBiomechanicsFluid MechanicsElectrostatic ActuationElectrostatic ActuatorsHydraulic ActuationHydraulic ActuatorsSoft ActuatorsTactile SensingElectromechanical ActuatorsHaptic Soft ActuatorsHydraulic Soft ActuatorsLarge-displacement ActuationResponse TimeShear Stress ForcesTransducersWearable Haptics
Wearable, soft, mm‑scale transducers that can generate dynamic mechanical stimulus on the skin are scarce, making touch underused in virtual reality, while achieving high force and large displacement in extremely thin actuators remains a long‑standing challenge. The actuators are fluid‑filled cavities with a metalized polyester shell and central elastomer that, when voltage is applied to annular electrodes, forces fluid into the stretchable region to form a raised bump, and a 5 × 5 array is integrated into a haptic sleeve. A 6 mm × 6 mm × 0.8 mm actuator weighing 90 mg produces over 300 mN force, 500 µm out‑of‑plane displacement, 760 µm lateral motion, responds in under 5 ms with 100 W kg⁻¹ power, and users distinguished normal and 2‑axis shear forces with over 80 % accuracy.
Abstract The sense of touch is underused in today’s virtual reality systems due to lack of wearable, soft, mm‐scale transducers to generate dynamic mechanical stimulus on the skin. Extremely thin actuators combining both high force and large displacement are a long‐standing challenge in soft actuators. Sub‐mm thick flexible hydraulically amplified electrostatic actuators are reported here, capable of both out‐of‐plane and in‐plane motion, providing normal and shear forces to the user’s fingertip, hand, or arm. Each actuator consists of a fluid‐filled cavity whose shell is made of a metalized polyester boundary and a central elastomer region. When a voltage is applied to the annular electrodes, the fluid is rapidly forced into the stretchable region, forming a raised bump. A 6 mm × 6 mm × 0.8 mm actuator weighs 90 mg, and generates forces of over 300 mN, out‐of‐plane displacements of 500 µm (over 60% strain), and lateral motion of 760 µm. Response time is below 5 ms, for a specific power of 100 W kg −1 . In user tests, human subjects distinguished normal and different 2‐axis shear forces with over 80% accuracy. A flexible 5 × 5 array is demonstrated, integrated in a haptic sleeve.
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High-Speed Electrically Actuated Elastomers with Strain Greater Than 100%
Ron Pelrine, Roy Kornbluh, Qibing Pei et al. · Science · 2000 · 3.2K citations