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Johns Hopkins University engineers have developed a pioneering prosthetic hand that can grip plush toys, water bottles, and other everyday objects like a human, carefully conforming and adjusting its grasp to avoid damaging or mishandling whatever it holds.
The system’s hybrid design is a first for robotic hands, which have typically been too rigid or too soft to replicate a human’s touch when handling objects of varying textures and materials. The innovation offers a promising solution for people with hand loss and could improve how robotic arms interact with their environment.
“The goal from the beginning has been to create a prosthetic hand that we model based on the human hand’s physical and sensing capabilities—a more natural prosthetic that functions and feels like a lost limb,” said Sriramana Sankar, a Johns Hopkins biomedical engineer who led the work. “We want to give people with upper-limb loss the ability to safely and freely interact with their environment, to feel and hold their loved ones without concern of hurting them.”
The device, developed by the same Neuroengineering and Biomedical Instrumentations Lab that in 2018 created an electronic “skin” with a humanlike sense of pain, features a multi-finger system with rubber-like polymers and a rigid 3D-printed internal skeleton. Its three layers of tactile sensors, inspired by the layers of human skin, allow it to grasp and distinguish objects of various shapes and surface textures, rather than just detect touch.
Each of its soft air-filled finger joints can be controlled with the forearm’s muscles, and machine learning algorithms focus the signals from the artificial touch receptors to create a realistic sense of touch, Sankar said. “The sensory information from its fingers is translated into the language of nerves to provide naturalistic sensory feedback through electrical nerve stimulation.”
In the lab, the hand identified and manipulated 15 everyday objects, including delicate stuffed toys, dish sponges, and cardboard boxes, as well as pineapples, metal water bottles, and other sturdier items. In the experiments, the device achieved the best performance compared with the alternatives, successfully handling objects with 99.69 percent accuracy and adjusting its grip as needed.
“We’re combining the strengths of both rigid and soft robotics to mimic the human hand,” Sankar said. “The human hand isn’t completely rigid or purely soft—it’s a hybrid system, with bones, soft joints, and tissue working together. That’s what we want our prosthetic hand to achieve. This is new territory for robotics and prosthetics, which haven’t fully embraced this hybrid technology before. It’s being able to give a firm handshake or pick up a soft object without fear of crushing it.”
This research was funded by the grant “Neuromorphic Feedback: A Strategy to Enhance Prosthesis Embodiment and Performance” from the Dept. of Defense through the Orthotics and Prosthetics Outcomes Research Program and the National Science Foundation.
Source: Johns Hopkins University