For individuals who have lost a hand, current prosthetic options come with difficult trade-offs. Rigid prosthetics provide strength but lack sensitivity, making it hard to handle delicate objects. On the other hand, soft robotic alternatives offer gentleness but don’t have the gripping power needed for everyday tasks. Most notably, neither option allows users to feelwhat they’re touching. However, a groundbreaking development by researchers at Johns Hopkins University may change the game entirely.

In a recently published study in Science Advances, the team unveiled a “natural biomimetic prosthetic hand” that combines the best of both rigid and soft materials while introducing an innovative touch-sensing system that mimics human skin. This hybrid prosthetic design could offer amputees a more natural, functional experience—one that allows them to interact safely and naturally with their environment.

The inspiration for this breakthrough came from the human hand itself, which blends rigid bone structures with soft tissues and joints. Rather than choosing between rigid or soft designs, the Johns Hopkins team sought to recreate this combination of strength and sensitivity in a prosthetic. The hand features a 3D-printed internal skeleton made of rigid material, which is surrounded by soft silicone joints that can be independently controlled. This dual-material design allows for both strength and flexibility, enabling the prosthetic to adapt to a wide variety of tasks and environments.

However, the true innovation lies in the prosthetic’s touch-sensing system, which is embedded in the fingertips. The researchers installed three different types of sensors in the prosthetic’s fingertips, replicating the function of mechanoreceptors found in human skin. These receptors detect various aspects of touch, such as light pressure, vibrations, and skin stretching. The artificial sensors work together to form a detailed picture of the objects the hand is interacting with. The system then converts the touch data into patterns similar to the electrical signals that our nerves send to the brain, offering a sense of tactile feedback.

In lab tests, the hybrid prosthetic hand demonstrated impressive performance. When asked to identify 26 different textured surfaces, including smooth plates and various ridged patterns, the hand achieved a staggering 98.38% accuracy. This was significantly higher than the accuracy rates of purely soft robotic fingers (82.31%) and rigid prosthetic fingers (83.02%). The hand was also put through tests involving 15 everyday objects, such as stuffed toys, fruit, dishes, and water bottles. Remarkably, the prosthetic hand identified these objects with 99.69% accuracy, adjusting its grip to handle delicate items gently and heavier objects more firmly.

One of the most remarkable feats involved the hand picking up a thin plastic cup filled with water using just three fingers—without crushing or denting it. This task would be nearly impossible for conventional prosthetics, highlighting the hybrid hand’s advanced dexterity and delicate touch. “We’re combining the strengths of both rigid and soft robotics to mimic the human hand,” explained Sriramana Sankar, lead study author and biomedical engineer at Johns Hopkins. “The human hand isn’t completely rigid or purely soft—it’s a hybrid system. That’s what we want our prosthetic hand to achieve.”

The prosthetic hand operates using electromyography (EMG), the same control method used in many modern prosthetic devices. EMG sensors detect electrical signals from the user’s remaining arm muscles, allowing them to control the hand’s movements by flexing those muscles intentionally.

According to Nitish Thakor, a Johns Hopkins biomedical engineering professor and study co-author, this hybrid dexterity isn’t just crucial for prostheses—it’s essential for the robotic hands of the future. “They won’t just be handling large, heavy objects. They’ll need to work with delicate materials like glass, fabric, or soft toys,” Thakor said.

The hybrid design also offers significant efficiency advantages. It generates three times more gripping force than purely soft robotic hands while requiring only a quarter of the air pressure to operate. For example, the hybrid hand generated 1.8 Newtons of force at just 7 psi (pounds per square inch), compared to only 0.55 Newtons at 28 psi for a soft robotic hand.

Perhaps the most exciting future potential for this technology is its ability to restore the sensation of touch. While the current study focused on demonstrating the hand’s physical capabilities, the design is intentionally built with sensory feedback in mind. “When you’re holding a cup of coffee, how do you know it’s about to slip? Your palm and fingertips send signals to your brain that it’s slipping,” explained Thakor.

This prosthetic system mimics this process, producing nerve-like signals that tell the brain whether an object is hot or cold, soft or hard, or even slipping from the grip. By restoring this sensory feedback, the prosthetic hand could help users better interact with their environment, making tasks like holding a cup or embracing a loved one safer and more natural.

The researchers at Johns Hopkins believe their innovation has the potential to revolutionize the future of prosthetics, blending the best of rigid and soft robotics with human-like tactile feedback. Not only could this hybrid prosthetic improve the daily lives of amputees, but it also opens up new possibilities for the development of advanced robotic hands capable of interacting with delicate materials in everyday life.

This breakthrough represents a critical step forward in making prosthetics not only more functional but also more human.

By Impact Lab