New technological advance in prosthetic technology by Indian Institute of technology kanpur

 

                                                                   Artificial Hands

Patients with limited hand function due to various medical conditions such as hand injuries, strokes, or spinal cord injuries (SCI) which often result in hand paralysis need artificial hands.

Types of Artificial Hands

1. Body-Powered Artificial Hands:
• Controlled by cables linked to a harness worn on the opposite shoulder of the amputated limb.
• Movement is driven by the user's shoulder and upper arm muscles.
• Limitations: Limited range of motion due to potential derailment of the cable system.
2. Myoelectric Artificial Hands:
• Use electromyography (EMG) sensors placed on the skin over residual limb muscles.
• Detects electrical signals from muscle contractions, which are then processed to control hand movements.
• Limitations: Expensive, requires regular maintenance, sensitive to sweat and moisture affecting sensor performance.

Challenges in Artificial Hand Technology

• Under-Actuation: This concept is beneficial for robotic grasping as it allows better power grasping and adaptability to various object shapes. However, distributing force evenly across all fingers remains challenging.

 

• Multi-Grasp Prosthetic Hands: Existing models use differential mechanisms for under-actuation within and between finger units. Although this allows for some flexibility, users still struggle with manipulating small objects and may find the prosthetics uncomfortable for extended wear.

         Technical Issues

• String-controlled systems can suffer from derailment if the strings are not properly aligned or become tangled.
• This can lead to unintended hand movements or the hand getting stuck, complicating control.

Solution to current issue

 Providing flexion and extension movements to the articulated finger units of an artificial hand, ensuring better performance, reliability, and user comfort​​.

How to increase the grasping power of artificial hand

Components necessary

1. Components:
• Differential Mechanism Unit: This includes a housing with guide rails and cable holders that work together to provide the necessary grip force for the finger units. The differential mechanism ensures that the artificial hand can grasp objects efficiently.
• Actuation Unit: Connected to the differential mechanism via cables, this unit drives the flexion and extension movements of the fingers. It operates by moving cable holders along guide rails, controlled by feedback from force sensors.
2. Control Unit:
• An electronic control unit (ECU) processes data from force sensors and controls the actuation unit.
• It adjusts the movements based on the contact force detected by the sensors to optimize user experience and outcomes.
3. Force Sensors:
• These are integrated into the finger units to measure the contact force with objects.
• The data from these sensors helps in tracking rehabilitation progress and adjusting resistance and assistance.
4. Materials:
• The housing is typically made of Polylactic Acid (PLA) plastic via 3D printing.
• Guide rails are made of stainless steel, and cables are often nylon for low friction.

Source of the solution

The source of above mentioned solution is based on the patent documents, which was granted patent on 09/02/2024, ( Patent No. 509038), on the title ‘SYSTEM FOR PROVIDING FLEXION AND EXTENSION MOVEMENT TO ARTICULATED FINGER UNITS OF AN ARTIFICIAL HAND’