Finalist in the RED CROSS international challenge

The “silicon-bio-hand” is a breakthrough in wrist and elbow actuated prosthetic hands.

Wrist actuated hands, being developed by the e-Nable community volunteers, are open source, simple and low cost hands getting fabricated by 3D printers all over the world. We 3D printed and tested the latest model from the community against a benchmark.

The “Grasp Diversity” benchmark determines the number of grasp forms, that can be imitated by a prosthetic hand, compared to the list of 33 human grasp forms. The hand was able to perform  5 grasps out of the list of 33 human grasp forms. So, we tried to  increase this number. Based on our previous experience on soft robotics and grasping field,  we identified 3 problems in the available model: in the fingers,in  the palm and in the position of the thumb.

After several simulations and experiments, the silicone-bio-finger was developed. It has a  3D Printed endoskeleton covered by a soft matter.  In order to get the best results in terms of bending forces, life cycle, stress distribution, and lateral deflections, we optimized some parameters, namely the joint geometry, the skin geometry, tendon routing, fabrication materials and manufacturing techniques.  We developed and tested over 200 prototypes of soft fingers in order to reach the best performance in terms of hand’s functionality and the life cycle of the fingers, to reduce the fatigue and to well distribute the mechanical stress.In addition, an adaptive soft palm was created and the thumb position was also modified to perform more grasps.

After integration of all these improvements we obtained a heartwarming result. The new Silicon-Bio-Hand can achieve 24 grasp forms, from the list of 33. This takes the wrist actuated hands to the next level.

The user can easily grasp and move a great range of objects. He can achieve precision and power grasps; , pick objects on the table or throw and catch a ball.  He can even grasp a cup and drink, grasp a spoon and eat or to hold a pen and write!

We are very  delighted  in taking this technology a step further.  Along with several other improvements, our main focus, currently, is working on the low cost production methods for high quantity and high quality development of optimal soft fingers. Our  vision is to deliver natural looking, simple, low cost and efficient prosthetic hands to people in need all over the world.