Capstan
Humankind Bionics · 2026– in development
Capstan is a glove with cables in it. The cables run along the same paths as the tendons in a hand, so closing the hand takes less strength from the hand itself. It is for people whose grip has weakened, in particular from Charcot-Marie-Tooth disease.
- 8 N grip measured without the glove, one user, in the lab about the weight of a full 750 ml water bottle
- 31 N grip measured with the glove tensioned, same user, same lab about the weight of a three litre jug of water
- 0 motors and batteries in the glove a dial and a ratchet hold the tension
- 5 prototype builds so far, V0 through V0.4
Cables run along the fingers where the tendons run. A dial at the wrist pulls them, and a ratchet holds them there, so the hand closes and stays closed without the muscles doing the work. There is no motor and no battery. Charcot-Marie-Tooth is an inherited nerve condition that wastes the small muscles of the hands and feet. Hand weakness is one of the main symptoms, and there is almost nothing sold that adds force to a hand.
I do the mechanical design, the prototyping and the testing.
I had assumed a weak hand drops things because the fingers slip, so I tried to fix the grip. I stuck rubber tips to the fingertips of a glove with double sided tape. It made no difference. The missing thing was the push of a finger into the object it is holding. So I went and read up on hand anatomy, and started work on cables that pull the way tendons do.
One person has worn it. In the lab that person measured 8 newtons of grip without the glove, and 31 newtons with the glove tensioned. It is one person in one lab, so nobody should expect the same numbers, and this is not a medical claim. Capstan is a mechanical grip aid. It does not treat or slow the disease.
A provisional patent application has been filed.