Overview of Status of Analysis, Design, Fabrication, Tests, etc.
Status of Analysis: Calculate motor parameters for remote control.
Design: An alternative drive mechanism is being designed on CAD. Remote control will use internal and external permanent magnet system. Hall sensor will be incorporated to assess magnetic coupling. Forward and reverse mechanism from simple magnet rotation. Lock mechanism using magnetic material in the device. No longer using SMA.
Fabrication: Drive mechanism parts (with plate) have been 3D printed at a 6:1 scale. Prototype #2 will be machined next week.
Tests: Drive mechanism (Prototype #1) is current wired and being tested. Risk reduction will be assessing if permanent magnetic system can rotate the magnet on the current prototype.
Accomplishments from Previous Week
Macy created CAD of first remote control actuation design.
Dingyi contacted FDA, and FDA responded with a statement that SMA is not an FDA regulated material. FDA approval is on a case-by-case basis after full completion of the prototype. From NuVasive interview, we learned about the remote control mechanism for limb lengthening system.
Ashley and Alec wired up prototype #1 and are re-designing drive mechanism based on testing.
Goals for Next Week (list names after each item). Use specific and measurable objectives.
Macy: Select remote control casing (3D print or purchase off manufacturer), select and purchase motor, determine hall sensor circuitry.
Dingyi: Contact potential metal 3D printer facilities for estimates. Learn safety behind machining Ti (Grade 2). CAD alternative drive system. Begin machining of prototype #2.
Ashley: Complete testing on prototype #1. Learn remote control mechanism, and begin integration with current and alternative drive system. Liaison between magnetic control and drive mechanism.
Alec: Complete testing on prototype #1. Design alternative mechanical drive system. Begin machining of prototype #2.
Sponsor Comments from Last Meeting and Actions Taken to Address these Comments (indicate date of comments and if via email or in person)
Suggestion: Plate design: determine a different method other than screws in order to attach plates to skull (due to the thinner skull of younger infants)
Action: Research to consider medical adhesives, adding a backside, absorbable materials
Suggestion: Remote control: consider a small integrated circuit. Small motor is possible. Make low-profile.
Action: Complete first design for remote control. Prototyping in process.
Requirement: Absolutely no openings or protrusions. Any gap is an open wound. Skin will heal over it.
Action: No longer considering alternative design that uses direct contact for current flow to device.
Instructor Comments from Last Meeting and Actions Taken to Address these Comments (indicate date of comments and if via email or in person)
Suggestion: Uses more data and specs. Remove transition slides. Mention how the current technology is part of the design challenge in that it exists in a larger scale.
Action: During NuVasive interview we learned that their two technologies use a torque output of 2in-oz (MAGEC) and 10 in-oz (PRECICE).
Suggestion: Consider risks: 1) Building prototype, 2) reducing size, 3) working titanium is doable but not easy
Action: Confirmed with Thomas Chalfant on machining with Titanium for prototype #2.
Comments from Other Students in the Class (indicate date of comments and if via email or in person)
N/A
Risks and Areas of Concern
How to create forward and backward direction of drive mechanism
How to determine which direction the drive mechanism is going after implantation
How to lock and unlock the device to change direction after implantation
Resources or Information Required but not Available
How to access and what is the cost of a metal 3D printer?
How can we gather quantitative yet more accurate measurements?
What remote control mechanisms are used for biomedical devices?
Schedule
Upcoming milestone: Integrating magnetic remote control into 3D printed prototype.
Updated Gantt chart (link).
Budget (list amount spent and amount remaining)
Spent: $0.00
Remaining: $4600.00
Progress on Report and Webpage
Completed design presentation this week and will be uploaded to website.