Design 1
The first design was drawn as a thin box resembling a thick iPad, with the screen facing upwards as shown in Figure 1. This design meets all the requirements as shown in the following description, denoted by the requirement number. The test strip brand would be selected on the screen and inserted on the side in a slot (Requirement 1, Requirement 3). The motor and color sensor would be placed adjacent to the test strip and the battery access would be on the bottom (Requirement 2, Requirement 4). To meet the sanitation requirement, the slot where the test strips are inserted can be sanitized through a disinfectant test strip (Requirement 5). However, this was seen as not as easily feasible. The microcontroller and wires will be isolated from the user, enclosed inside the box and the SD card will be placed on the bottom part on the side (Requirement 6, Requirement 7). This design also incorporates legs on the upper side of the bottom that flip inwards for the device to lay flat or flip outwards to tilt the device for an easy user interface.
Figure 1. First design sketch of the device.
Design 2
The second design was drawn as a box with the screen in the front with the placement of the color strip on top and is shown in Figure 2. A lid similar to a printer’s lid was designed to close on top of the color strip in order to create a dark environment for accurate sensing. The lid would contain the linear actuator and color sensor on the bottom side, facing inwards towards the color strip. The Arduino, battery, SD card and wiring will all be placed in the area behind the screen inside the box. This design fit all the requirements because the screen would be the way the device can take input from the user, it can detect color using the color sensor and linear actuator placed under the lid, it can output the results through the screen, it will be powered using an battery placed internally, it is sanitizable because the top of the box and the lid can easily be wiped down, it will meet the electrical safety standards IEC 6060 since the microcontroller and wires will be isolated from user, and it will to be able to store data through the SD card, again placed internally.
Figure 2. Second design sketch of the device.
Design 3
The third design was drawn as a box with the screen placed on the top, and a drawer that allows for the placement of the test strip (Requirement 1, Requirement 3) as shown in Figure 3. The motor and color sensor will be placed above the test strip with battery access on the back side of the device (Requirement 2, Requirement 4). The drawer system allows for easy access to sanitize the area that comes in contact with the test strip (Requirement 5). The microcontroller and wires will be isolated from the user inside the device to ensure electrical safety (Requirement 6) and the SD card will be placed on the bottom part on the side near the Arduino nano.
Figure 3. CAD of final design addressing electrical components