We will be posting weekly updates every Monday on the progress of ZEFYR. Each post consists of updates from each of the teams - mobile app development, hardware, mechanical design. HardwareAll the purchased hardware has arrived and testing on each component to characterize them has begun. In addition, the components need to be tested to ensure that they perform the same as specified on the data sheet. The purchased components included LEDs, pressure sensors and new batteries. First, the LEDs were tested to ensure that they work, and that they would light up with the expected forward voltage applied. Additionally, some of the LED channels (we purchased RGB LEDs) were tested under conditions where more than the recommended maximum forward voltage was applied. Some of the channels had a maximum forward voltage of less than 3.3V, which was the lowest power voltage rail on the microcontroller. These tests showed that resistors would be needed to drop the forward voltage before the LEDs are used with the microcontroller. Another test performed was a test using the thin film pressure sensor. The plan was for this sensor to be placed under the inhaler where the thumb would rest, to measure the squeeze force applied when the user would actuate the medication canister. The thin film pressure sensor is effectively a resistor, and when force is applied onto it, the resistance decreases. This resistance change can be used to measure the force applied onto the inhaler. To measure the resistance change reliably, a voltage splitter circuit was used. When the resistance of the sensor changed, the voltage over the static resistor in the circuit would change accordingly, and the applied force could be measured. Using a 10 Kohm resistor, the voltage across the resistor when the canister was actuated was over 2.1V. This means that if the microcontroller measures a voltage across the resistor over 2.1V, it can be deemed that the user actuated the canister. Different resistors can be used if a larger range is desired. Using a 1 Kohm resistor resulted in the voltage measuring 3.3V when the canister was actuated. The voltage change due to different pressure applications can be seen in the images below. Mobile App DevelopmentWe are working towards developing an Android application to allow users to view more information about their inhaler technique post inhaler usage. Since the goal is to create a working prototype, only an Android app will be developed in the interest of time. Future work would be to create an iOS app as well. This past week was spent further defining the requirements for the app and dividing the work between the mobile app development team. Work on the app has also begun. Since the team members are all pretty new to app development, a large portion of the week was spent doing research to understand basic app development. What was accomplished this past week:
Mechanical DesignThe current 3D model of the ZEFYR product is shown in blue in the CAD model. A quick prototype was 3D printed in a PLA material, shown in red. Keep an eye out for updates to the model as room is made for the hardware components and the printing material is modified. For this coming week, the focus will be create the model of the orifice plate that will accompany the differential pressure sensor to measure the inhalation rate. MarketingWe have started looking into possible software and methods that will help us create the marketing and demo video for the project once it has been completed. Information from the work completed last term is also being compiled for the presentation poster.
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AuthorsMatthew, Patricia Archives
March 2021
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