This 3D-Printed Robotic Hand Can Grab From Both Sides

Robotic hands have a basic limitation that most of us never think about. A human hand is built to grab things with the palm side. To pick something up from the other direction, you have to twist your wrist or move your whole arm. Robots have the same problem, and it makes them slower and clumsier. A team of researchers has now built a human-sized robotic hand that can close its fingers forward or backward, so it can grab from either side without repositioning its arm.

The hand is 3D-printed and surprisingly light — about 220 grams, roughly the weight of a cup of coffee, and about 8 inches long. Instead of springs that snap parts back into place, it uses a cable system much like the tendons in your own fingers. Cables pull in both directions, which lets every joint swing past its resting position. That's the trick that makes two-sided grabbing possible. The team reports the fingers can press with about 29 newtons of force, enough to hold a full 2-liter bottle, and they land within 0.15 millimeters of the same spot each time.

In testing, the hand passed all 33 standard grip types used to classify how hands hold objects, and scored 8 out of 10 on the Kapandji test — a simple thumb-to-fingertip touching exercise doctors use on people. It also successfully picked up objects using both the palm side and the back side.

Why does this matter outside a lab? Robot hands are one of the biggest bottlenecks in automation. Warehouse robots, factory arms, and eventually home helper robots all need hands that are cheap, light, and flexible enough to handle everyday objects. A 3D-printed hand that can grip from any angle could mean fewer awkward arm movements, faster pick-and-place work, and lower hardware costs. There's no word yet on commercial availability or real-world testing outside the lab.