This project is a favorite of mine and actually my first commissioned piece. A friend of mine was on the board for a developing new learning commons in the Biomedical Engineering building on campus at Georgia Tech. I pitched this idea to the team and they were all behind me making this as a piece of wall art for the space! Unfortunately this project was from several years ago long before I realized the benefit of proper process documentation, so my build process pictures are sadly lacking.

The concept itself began very humbly: A motor-driven cam which drove an arm back and forth, with the end of that arm jumping back and forth between the outline of 2 neurons. A small something could then be put on the end of this arm to symbolize a neurotransmitter crossing the synaptic gap, and a brain would be illustrated onto the cam. Each time this cleared the gap, a circuit would close and illuminate a light bulb above the brain!

It started with this concept sketched out:

Concept.jpg

The final version took all the principles shown in this sketch and simply cleaned them up. I decided to make it more visually appealing by framing the whole sculpture in a rectangular frame. This updated idea was very hastily drawn as the depiction below, but it shows how the shape evolved from the very first iteration shown above.

20150414_003430.jpg

In the final design, the rectangle was 16″ by 10″ in order to adhere to the golden ratio. The transverse movement of the neurotransmitter was provided by a four bar linkage (circled with the dotted line) to keep the cam-driven arm horizontal. The dendrites of the original design, being  very complex shapes, were simplified to a more zoomed-in view of a single synapse in which both sides were simple rounded shapes which would be much easier to machine. With the design fully planned, each part was drawn out and cut out of 1/4″ aluminum sheet using the water jet cutter in the Invention Studio. The cut lines looked as such:

Cut lines

The two shapes at the top represent the pre-synaptic and post-synaptic neurons, and the egg-like shape based at the origin is the cam. It is a half circle and a half ellipse, which allow the arm driven by this cam to remain in the same place for 180 degrees of the cam’s rotation and only be driven by the change in radius brought on by the elliptical half. I used a fine sander to polish the roughly cut edges of the cam and arm to minimize the friction between the two. A spring was used to keep the arm up against the cam, with a guide piece placed on top to keep the edges in line, as the spring wanted to pull the arm and four bar linkage backward out of the plane of action.

The motor was mounted to the back of the frame using an L-bracket. Once it was in place, I was able to run it and test that the linkage and cam were working effectively. The end of the cam-driven arm ended up perfectly traversing the gap between the neuron pieces!

Progress gif true

The brain on top of the cam was added after this mechanical test was filmed. It was fashioned out of a circular piece of copper on which I laser engraved the image of a brain. Since the metal itself could not be directly engraved using the laser I used Cermark, a metal marking solution, to coat the copper. Using very high power I then blasted it onto the copper using the laser. The small diamond piece representing the traversing neurotransmitter was also fashioned out of copper for consistency. Copper now complemented the aluminum on both halves of the sculpture.

Lastly was the light bulb system, which was very fun to work on. Behind the top bar of the rectangular frame was a small copper plate which stuck out, and a wire was attached to one of the bars of the four arm linkage. A wire attached this ran back to the base of the light bulb where it was soldered on. Thus when the arm was driven and the bars in the linkage rotated, the wire made contact with the copper plate which completed the circuit and lit up the bulb.

With both the electrical and mechanical components of the sculpture assembled, it was done!

Finished True

The only part not pictured in this video was a holder for the 9V battery that drove the motor. This was a simple 3-D printed open top box and was positioned on the back of the right frame piece and adhered to the top of the motor. This was sturdy enough to keep the battery in place with just gravity and required no mechanical force or tools to replace the battery.

battery holder

You can also see in the above .gif that the sculpture is standing on the table top, supported by the very long screws which held together the corners of the frame. Wall adapters were also 3-D printed which were designed to be hung on a wall using standard nails.

mount

These are hung by hammering a nail through the small hole so that the long screws of the sculpture slide securely into the cylindrical fittings. This allows the sculpture to be hung on the wall securely but also removed to be displayed on a tabletop.

This project ended up being a lot of fun to work on and definitely helped me improve my prototyping and design skills. Thank you for reading!

 

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