Mr. Ajith Nihal has lost four fingers in his left hand due to a factory accident. Even though he does not have four fingers he is doing his primary work alone from his dominant hand. Mr. Ajith wants to contribute in his day to day activities especially in farming using both hands

·        Difficulty performing farming tasks with one hand including,

•  Using a mammoty for digging and soil preparation.
•  Operating a grass-cutting machine.
•  Cutting branches while climbing trees.
• Tying strings and handling small objects.

•   Shaking hand(injury hand)
•    Limited movement of the little finger.
•    Restricted wrist mobility

• Should look like a real hand to avoid the need to hide it.
• He needs to get support from his left hand when holding tools with his dominant hand while farming.
• Easy to wear and remove independently.

A design uses a spring mechanism to bend the fingers of the prosthetic hand. Each finger has two hinges and bending the fingers using strips, but since we faced issues where to place springs , So we moved to another mechanism.

Design a three-fingered hand with a palm, featuring three hinges per finger for natural movement. The user can manually bend the fingers at the hinges, enabling various grip positions to support the dominant hand.

·

• Two mechanical hinges per finger for natural flexion.
• Manual Bending- User applies force directly to bend fingers.
• Grip Control- Manually positioned fingers offer stable object support.

Since the hinges are not stably positioned when in a gripping we moved to another mechanism

Twine strips are integrated into the fingers to provide flexibility. Each finger has two hinges, and when tension is applied to the twine from other hand by pulling the strip, the fingers bend directly at the hinges to grip objects.

After we did the 3D printing of hinges and finger digits, we tried to assemble the fingertips using hinges, but there, some hinges and finger digits were broken when we tried to send hinges through the finger digits and assemble the fingertips.

So here instead of hinges, we use zip lines to connect the digits and bend the fingers which are easy of use and cost-effective. This costs only Rs.3($0.009 ) in the Sri Lankan market.

Designed 3D finger digits with two segments for durability and flexibility using lightweight PLA filament. Connected segments with zip lines and tested strength and flexibility. Developed functional thumb, index, and middle finger tips for tool grasping.thumb finger tip index , middle

Input twine straps through hollow finger sections. Extend twine outwards to control finger bending and straightening. Pulling the twine should mimic natural finger curling. Use a simple pull-and-release mechanism for ease of use. Choose strong, weather-resistant twine for outdoor durability.

Designed a robust, ergonomic palm structure using TPU to support finger attachment.  Palm include secure slots  for zip lines . Ensure a cushioned or shaped inner surface for comfort. Provide sufficient surface area for a firm grip on tools like a mammoty or grass cutter.

Provide stability and support for the prosthetic hand using lightweight, TPU 3D design. Designed a mesh-like arm guard for comfort and efficiency. Cover the forearm with adjustable strapping. Forearm plate with velcro strap control and ensure protection from friction and pressure.

The threaded bob secures the twine strap, ensuring stability and precise finger movement. It allows tension adjustments, improves grip control, and distributes force evenly, enhancing durability and reliability. 

The middle joints of fingers add an extra digit and more hinge support for the fingers .middle joint