Weekly Progress

Week 1

4/4/2017:

During the first day of lab, we met with our predetermined team
We started to brainstorm and critique different concept sketches. These can be shown below as Figures 1 and 2
We began setting up our Engineering Design Lab Notebook and the blogger
Throughout the rest of the week, we will continue to update the blog and complete the Project Design Proposal

Figure 1

Figure 2

Week 2

4/10/2017:

Scheduled weekly meetings with adviser for the rest of the term
Met with group to complete the project proposal form
Set up Gantt chart to pace our progress as the term progresses
Did some research about where to obtain materials and what materials may work
Figure 1 shows the design for the device in which an external magnet field can rotate a magnetic implant

As the implant is rotated, a plastic rectangle on the back of the implant begins to turn into a helix. Once this helix reaches a specific length, the forces would turn into linear motion through the helix "screw."

Week 3

4/17/2017:

Purchased materials, ETA: Monday, 17th
Did preliminary research on using MATLAB to model magnetic fields and using this for motion through brain tissue
Did preliminary research on the movement of objects through gel-like materials

Week 4

4/24/2017:

Materials arrived, our group started to make multiple tubes of gelatin for initial testing
Since the test tubes are made of glass, many of them broke during the gelatin making process

We decided to buy new, plastic test tubes for safety reasons

Tested a rough design of the magnetic implant in a gelatin

We used small, 25 mm external magnets for this test
For the next test, we plan to use larger magnets in order to create a more uniform magnetic field through the test tube
Demonstration of fast, nonuniform movement through the gelaltin can be seen in Figure 1
Figure 2 shows the method of our first implantation of the magnet into the gelatin (plastic tweezers)

Figure 1

Figure 2

Week 5

5/2/2017:

Took measurements of materials (Figure 1). This includes magnets and test tubes. We plan to use these measurements to create a 3D printed apparatus for the instrument
Created a prototype design screw for the magnet to go inside of as shown below (Figure 2)
Designed schematics of prototype apparatus. Isometric views and measurements of this apparatus can be shown below in Figures 3-5

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Week 6

5/9/2017:

3D printed the first prototype for testing our magnets and gelatin (Renders shown in Figures 1 and 2)

Tested thicker gelatin with 1/4th cup of water to to 7g of gelatin
Used 1" dia. x 1/8" thickness magnets for initial prototype magnet

Began working on our MATLAB program for analyzing the magnetic fields of our magnets.
A big problem was stabilization of the magnet in the gel

Getting the magnet to stay in the center of the gelatin, which is partially solved by a thicker gelatin with a temperature of 35 degrees Fahrenheit.
Ensuring movement of screw was caused by screwing motion, not magnetic fields of magnets

Figure 1: Front isometric view of apparatus magnet rack (v1)

Figure 2: Front isometric view of apparatus base (v1)

Week 7

5/16/2017:

Redesigned our apparatus using Creo Parametric in order to accommodate for our larger magnets.
Started shopping for magnets with a stronger magnetic field and smaller magnetic gradient

In order to find the magnets we needed, we used a calculator that is derived from a series of finite element analysis studies for a pair of equal sized disc magnets in free space
Figure 1 shows the field graph for two equal magnets of 2" dia x 1/8" thickness with the size of the gap determined by the apparatus. In the gap, there is an extremely small gradient, which should reduce any linear force by the external magnetic field

Unsuccessfully 3D printed base of the design

Base would not print flat
Delayed progress in testing prototype and gathering information

Needed a presentable version of the apparatus for the poster contest so we constructed temporary magnet holders (Figure 2)
Possible alternative design

More stabilization of magnet in gelatin, which means more accuracy in the distance the magnets are held
More stable test tube resting in apparatus
Larger range of motion that can allow the external magnets to travel the whole length of test tube

Figure 1: Field Strength vs Distance from Center Axis

Figure 2: Apparatus v1 with temporary magnet holders

Week 8
5/23/2017:

Renamed PMIN (Precision Magnet Implant Navigator) to BINS (Brain Implant Navigation System) for logistical reasons
Finalized Creo Parametric apparatus design for accommodation of larger magnets and printed out the new design (renders shown in Figures 1-5)

New apparatus design also improves on fallbacks to first version including stability and range of motion

Successfully tested the second prototype as seen in Figure 6 and 7

Figure 6 demonstrates the range of movement of the apparatus. It allows for full rotations around the test tube, as well as for the external magnets to travel along the full length of the test tube
Figure 7 shows the initial test of the implant design with a 1.0 mm thread size. Note that as the tube is rotated, the implant does not because it is held in place by a torque from the magnets. The screw showed no linear motion however.

Tested multiple screw designs

Thread sizes were 0.5 mm and 1.0 mm
Thread counts ranged from 1 to 7 threads

These screws showed no signs of linear motion, however, rotation motion was working

This made a point to us that the screw was working, but the threads just weren't grabbing onto the gelatin

Figure 1: Front isometric view of apparatus base

Figure 2: Top isometric view of apparatus base

Figure 3: Bottom isometric view of apparatus magnet rack

Figure 4: Front isometric view of apparatus magnet rack

Figure 5: Top isometric view of apparatus magnet rack

Figure 6: Range of motion test

Figure 7: Initial torque test of external magnets on implant

Figure 8

Figure 9

Week 9

5/30/2017

Tested several previous thread sizes and thread counts a second time in the apparatus and recorded distance data

All versions of the 0.5 mm and 1.0 mm screws showed no signs of linear motion

New screws were redesigned and printed in an attempt to make a screw that will travel through the gelatin more effectively

Threads were made larger (1.5 mm and 2.0 mm)
Points were added mimicking the design of a wood screw
Printing was limited by success of 3D print

Several screws printed support material which degraded the quality of the screw to the point that we could not use it
Screws with threads of 2.0 mm or greater would not print correctly
Screws with threads of 1.5 mm and with a thread count greater than 1 would not print correctly

First successful movement through the gelatin was shown in implants with thread length of 1.5 mm and thread count of 1. This design is shown in Figures 1 and 2.

Important to note that minimal damage was shown in the gelatin as the screw traveled

Recorded results on distance the implant moved per revolution of the test tube for the 1.5 mm threaded implant

Gathered distance moved in increments of 10 from 10-100 revolutions
Plotted data and found a linear relationship between revolutions and distance moved (Figures 3 and 4)
The first trial showed to be slightly inconsistent, however, once the technique was refined for placing the external magnetic field and rotations, the second trial showed more consistent data