Overview
This project was started out of a need for a mechanism to load foam micro-vents into a circular cartridge developed as the platform for a bioweapon detection assay system. The vent-loader proved to be a cost effective solution to the problem of loading the vents into their cartridges, and also decreased loading time by over 50%. As this project took place at Lawrence Livermore National Laboratory, only renderings of the final device have been cleared for release.
Assay Cartridge with Vent Slots along the Outer Rim
Ideation
In order to design a mechanism that could accurately and reliably load vents into cartridges, it was first necessary to determine how the vents could be manipulated. The loading process was broken down into three steps: [1] orient the vents vertically, [2] position the vents above the cartridge's slots, [3] press the vents into the slots until flush with surface.
Design
[1] Orienting the Vents
A vibrating hopper-funnel feeder was chosen as a viable option for manipulating the loose vents into a vertical orientation. To ensure that the vents would properly drop into the channel, seen in the images below, the angle of the funnel's slope, the diameter of the inner channel itself, and speed of the 3V micro-vibration motors had to be adjusted until proper function was achieved. Holes were incorporated along the side to allow the user to see how many vents had been successfully loaded into the channel. The tab at the bottom of the feeder was added to limit the base to 90 degrees of freedom of rotation. 
[2] Positioning the Vents 
To make sure the vents were only dropped directly above the slots they were meant to be inserted into, a template part was designed to guide the feeder to drop the vents into position. This template, seen below with the hopper-funnel in position over it, positions vents above their slots on the main cartridge, ensuring their proper placement. The template and cartridge are rotated, allowing the hopper-funnel to drop vents into each slot position one-by-one.
[3] Inserting the Vents 
A multi-pin plunger was designed that would be able to insert all of the correctly positioned vents into their slots at once. The plunger was machined from aluminum and included in an insertion mechanism that used two spring mechanism to reset the plunger after pushed down for inserting the vents. 
Prototyping
CAD models were designed in Solidworks and printed on a Stratasys dual-nozzle FDM 3D printer. Prototypes were tested and re-designed multiple times in order to perfect the underlying mechanism needed to accomplish each step and to test the assumptions made in the ideation phase of the project. Press-fits and sliding-fits were adjusted to account for variations in the 3D printing process. Prototypes were also sanded to achieve final characteristics. 
Final Product
The final vent loader was a desktop device consisting of 16 3D-printed, machined, and off-the-shelf parts. The gear train seen below was added to control the speed of the cartridge and template as it rotates during loading, as a constant speed was found to ensure proper loading during testing. The vent-loader proved to be a cost effective solution to the problem of loading the vents into their cartridges, and also decreased loading time by over 50% compared to manual loading.
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