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.
The ability to mechanically stimulate touch receptors over the entire body is a key feature for fully immersive and highly realistic virtual reality experience. Haptic stickers, flexible arrays of HAXELs (hydraulically amplified TAXels), that enable cutaneous haptics over nearly all parts of the body, are reported. HAXELs are zipping electrostatic actuators that combine stretchable elastomers and high permittivity flexible films to generate both high strains and high forces, from DC to 200 Hz. A fabrication process that enables scaling HAXELs from 2 to 15 mm in diameter is presented, allowing to tailor the actuators to different body parts and to wearables such as wrist‐watches. The different sizes of HAXELs generate blocked forces from 100 to 800 mN, with DC displacements from 100 to 850 µm, well above sensation thresholds. Haptics tests of Haptic Stickers, 5 × 5 arrays of 10 mm diameter devices, on palms, back of the hand, neck, arm, and back of a dozen volunteers, are done with users reporting high pattern recognition success on many body locations. The Haptic Stickers uniquely offer a thin and lightweight form‐factor, which does not limit the freedom of motion of the user, compatible with untethered scenarios.
Inertially stabilized platforms are widely used in order to provide a stable line-of-sight for optical components such as cameras, lasers or mirrors. They are often difficult to miniaturize because of the need for multiple degrees of freedom and high dynamic. Ultrasonic motors provide an interesting solution since they can provide high torque at low speed without the need for extra mechanical parts.
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