Final Design

Functional Requirements for MAE and ECE:

• • Develop a magnetic stirrer that utilizes electromagnetic coils to alternate between spinning both small (0.5 mL to 5 mL) and large (5 mL to 250 mL) volumes of liquid.

  • Expand the current 9 coil array to spin more vials simultaneously. Explore using 81 coils.

  • Keep the overall thickness of the device near the same from last year’s group (~10mm).

  • Have the device completely sealed so that it is able to survive IP67 testing.

  • The device should be controlled through physical interaction as well as through an app.

  • Ensure the housing of the device is compatible with inductive charging.

  • Incorporate a Printed Circuit Board in the device.

  • Optimize the electrical components to meet an 8 hour battery life.

FINAL Design:

Components:

Conclusions:

Overall the project ran into some shortcomings. Our group, consisting of two mechanical engineers and two electrical engineers, ended up pursuing a 36 coil array with the sponsor’s approval, which should have theoretically been able to spin 25 small vials and 4 large vials at one time. The group ran into issues when incorporating a printed circuit board in the device as the pcb was not providing power to the magnetic coils. The reasons for this is probably due to a design error in the PCB, or a soldering error when soldering all of the electrical components.

Prototype models were done leading up to the quarter as the group was testing 9 of the 36 coils without a printed circuit board. When testing the 9 coils, the group was able to successfully spin 4 small vials at one time at up to 1200 RPM and 1 large vial at 800 RPM.

The device ended up resulting in 12 mm thickness, 2 mm bigger than last year’s capstone group and this can be explained due to ordering a thick printed circuit board. The project was pressed on time so the printed circuit board had to be ordered in standard thickness rather than  ordering a specialized thin board. The device can be reduced to 10mm and the suggested actions to do so have been provided to the sponsor. The device can be controlled through physical interaction through capacitive touch sensors, once the printed circuit board is properly functioning. However, due to time constraints, the device can not be controlled through a phone application. The theoretical battery life of the device calculated was 10 hours, but has not been tested due to time constraints. The theoretical value is likely to be larger than the actual battery life. Lastly, the device was completely sealed and passed IP67 testing, and is compatible with inductive charging.