Apertures are used in optical systems to limit the luminous flux. In the human eye the iris serves this purpose but can be damaged requiring an implant, which to date is static, limiting the optical performance. The authors thus report the development of a prototype demonstrating the feasibility of a flexible dynamic iris implant manufactured with an automated manufacturing technique. The presented actuators are printed via aerosol jet printing allowing a high reliability in produced electrode quality. Through optimization of the actuator design for maximum contraction they demonstrate a pupil area reduction of 13.40% or 6.94% reduction of pupil diameter, respectively. Thereby the prototype demonstrates an illuminance reduction of 18.25% in the central visual axis. Furthermore, they present a first iteration of a bionic closed-loop control mimicking the human iris reflex thus laying the foundation for a self-controlled iris implant.
For long-range swimming fish, low cost of transportation is a critical requirement. This also applies to autonomous fishlike robots (AFR). As with their biological cohorts, AFR require sensory input that characterizes the flow of the water surrounding them. Thus, there is a need for low power hydrodynamic sensors that can be deployed on a fish-like robot, and which can provide flow information from open water conditions. Electroactive polymers offer opportunities for flow sensing on soft and flexible AFR.We developed and evaluated an approach for capacitive electroactive polymer flow sensing. This uses dielectric elastomer sensor membranes mounted on a liquid-filled cavity protruding into the flow. Flow speed and incident angle on a hydrofoil standing in for the fish are registered through electrical capacitance changes resulting from deformation of its 350μm thick membrane. Through its triple-electrode design, measurements are largely shielded against the influence of the surrounding water on the capacitor. Differences in flow speed along the sensor can be detected with high reproducibility for extended durations of time. The developed sensors were assessed regarding accuracy, reliability, and durability.For performance and long-term testing, an automated tabletop water tunnel test rig was created. This setup enables sensor testing for flows up to 1 m/s with automated incident angle control and data logging.We are thus presenting further steps towards robust ocean-faring hydrodynamic sensory systems by demonstrating advances in electroactive sensory technology and testing facilities.
We have developed a diver-robot empathetic communication system that allows the diver to feel the disturbance around the robot and control the robot remotely using hand gestures. The underwater robot is embedded with soft dielectric elastomer (DE) sensors to sense the direction and amplitude of the disturbance around its surroundings, defined as the physical indentation of the eye sensors. The direction and intensity of the disturbance communicate to the user remotely via an array of vibrotactile actuators in the form of a bracelet. Wears of the glove will feel what the robot is going through, represented by different vibration intensities and patterns. The smart glove employs five dielectric elastomer sensors to capture finger motion and implements a machine-learning classifier in the onboard electronics to recognize gestures. Hence allowing the wearer to send commands in the form of hand gestures for correcting the underwater robot’s posture. The system will be tested in a user study to determine performance improvement over the traditional robotic control interface. Our work has demonstrated the capability of DE sensing for advanced human-machine interaction.
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