Biomechanical Finger for Teaching Anatomy 2021-2022

My capstone project motivation was to make a model to teach the flexion and extension of the human index finger to anatomy students. With this in mind, my team of four came up with the following primary objectives:

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1. Interactive

2. Tangible

3. Ease of Assembly

4. Adjustable

5. Free standing structure

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I developed the initial concept, shown in the drawing on the left.

I then made the SolidWorks model for the finger. The intial design (shown on the right) was prototyped but had issues replicating the motion correctly due to gravity. Thus, the second iteration was developed by mounting the finger to a vertical board. 

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The tendons were not modeled in SolidWorks due to the flexible nature. 

Intial Design

Second iteration

The final design is shown on the left. It consists of the three finger phalanges plus the modified knuckle joint 3D printed using PLA. The finger was conected using nuts and bolts, to allow for easy replacement of components. The tendons were modelled using nylon cord, and rope guides were used to model the retinaculum which keep tendons in place while allowing them to slide. The extensor hood, the most complex tendon used for extension and flexion, was modelled on Solidworks and 3D printed using TPU to allow for motion. The model was assembled and then mounted on acrylic that was laser cutted. Clear acylic allows the user to see the model on all sides, with clips that allow the tendons to lock in place to freeze the position of the finger. ​

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The client was extremely satisified with the finished product, and as a result requested the team make three models for her.