The main structure of the built product was fabricated with natural high density polyethylene (HDPE) on the manual and CNC mill in the machine shop. This material was selected due to it being both highly durable and easily machined. The structure was put together using thread-forming screws designed specifically for use with plastics.
The lids were fabricated from polycarbonate. This material was chosen based on it being clear, easily machined and very durable. The lids were created using two rectangular pieces of polycarbonate which were connected using #6-32x5/8” machine screws. The screws also doubled as the mates to the magnets that hold the lids closed and depress the sensor pins. The lids were attached using ¾” brass hinges. Each compartment uses 2 Neodymium magnets, one is 3/16” in diameter and the other is 1/8”. The larger magnet provides roughly 2.4 pounds of force while the smaller provides 0.8 pounds. The compartments were created using communion cups that are recessed in holes (15/16”) which allow the upper half of the cup to be grasped for easy removal as well as aid in taking the pills.
The sensors for each compartment were placed in channels created on the CNC mill. The channels were filed to remove the rounded corners and allow the rectangular geometry of the sensor to fit properly. Once in place they were installed using 2 M2 x 12mm pan head machine screws. The LEDs were installed in holes drilled on the CNC mill and mounted by using LED clips that keep them in place and inhibit the light from traveling into the HDPE or adjacent compartments.
Arcade buttons were also installed to allow the caregiver to set programs, prepare for removal of the SD card, and turn off the lights and sensors to load the pill compartments. The LCD screen was mounted through a hole in one of the HDPE panels and the speaker was placed behind a series of holes that allow the sound to travel out of the device easily. A channel was created that allows the SD card to be removed by the caregiver. A toggle switch was installed on the side of the device, through a small channel made using the CNC mill, to grant the caregiver access to the programming mode. The other side of the device has a hole that allows the adapter to be plugged in and power the pill box.
The electrical design centers around the Due controls for the overall operation of the whole system. There is also a real-time clock that keeps track of the current time. The master Due compares the scheduled time with the real time data in order to determine when it is time to issue a reminder message if the user has not yet opened the intended compartment within any active grace period. Similarly, the Due also issues a warning message if the user opens the wrong compartment at the wrong time. The user activity is recorded in a separate MicroSD card, which interfaces with the master Due via an SPI protocol. The master Due formats the strings that are to be written to the SD card using built-in library functions. A simplified architecture of the whole pill box is included below.
- High Density Polyethylene (HDPE)
- Parts fabricated using the manual and CNC mills in the student shop
- Side supports fabricated using manual mill with ½” end mill
- All other parts fabricated on CNC mill
- SolidWorks part files converted to DXF files to use program mode on CNC mill
- All parts connected using Thread-Forming Torx Screw for Plastics, Flat Head, Zinc-Plated Steel, #6-19 Thread, 1/2ʺ Length
- All electrical components were mounted in their respective locations using suitable fasteners
- Polycarbonate lids
- 2-piece design put together using #6-32x5/8” steel Phillips flathead machine screws
- Drill-point countersink used to allow screws to sit flush with surface
- Slip fit through bottom portion of lid
- Attached to structure using ¾”x5/8” brass surface mount hinges
- Magnetic Latch mechanism
- 2 different sized Neodymium magnets press-fit into HDPE
- 3/16” diameter magnet provides ~2.4 lbs. of force
- 1/8” diameter magnet provides ~0.8 lbs. of force
- Magnets mate with screws used to put lids together
- Cherry snap action switches used to track compartment activity
- Latch mechanism depresses pins on switches
- Installed in channels created using the CNC mill and a file with 2 M2 x 12mm pan head machine screws
- LED clips used to hold LEDs in place
- Outer ring of clip press fit into pre-drilled holes
- LEDs pressed into inner portion of clip
- LEDs and inner portion snap into outer ring
- Pill Cups
- Hold pills and rest in 15/16” holes drilled using CNC mill which allow the upper half of the cup to be grasped for easy pill removal