We do all we can to prevent sports injuries, but they do happen—and when they do, what can athletes do next? They can go to physical therapy, they can get poked and prodded with calipers and protractors, and they can document their complicated exercise regimens when they go home. What if tracking the recovery process could be as simple as tapping a button on your phone? That's what inspired FLEX: a device, app, and website to continuously track flexibility in affected joints, share recovery data with healthcare professionals, and mark milestones on an athlete's path to getting back in the game.

What it does

Using adjustable straps, the patient places the FLEX device on any rehabilitating limb and selects options in the FLEX app to record both baseline data points to track range-of-motion progress and normal exercises to track reps. Physicians assign exercises to their patients within the app and can choose dates, duration, and number of times a day for patients to complete exercises. The device itself uses accelerometer data to find the maximum angle an athlete achieves during a stretch. Then the athlete can access data about their flexibility goals and progress in both the FLEX app and website.

How we built it

The FLEX device is a wearable device with an accelerometer, OLED display, and WiFi-enabled Particle Photon development board. Using Particle's WiFi capabilities, the Photon code detects when a signal is sent from the app to gather data, and it responds by sending accelerometer data to a Firebase database. The database is accessed by both the associated mobile app (which records data) and the website for viewing long-term improvement statistics. The patient's PT loads exercise routines into the database, which patients can view and update from their app. This lays out detailed exercise schedules and periodic baseline evaluations to track progress.

Challenges we ran into

We ran into and solved a couple of issues along the way:

1) Some of us had diverging views about what data should be gathered with exercise regimens due to a minor communication oversight. One of us thought we had decided to measure angle data every workout, while another thought only the number of reps were being recorded for some measurements. Fortunately, we were able to come to an agreement about what should be recorded and when, which allowed us to move on with development with all of us on the same page.

2) Late in the development of the product, we had an electrical short between the power and ground wires in our device, which started smoking ominously! Luckily, we were able to disconnect the device before damage was done to the major components, so we only had to replace two wires (after wrapping one in electrical tape!)

3) Early on, we ran into issues with the data transmission limitations of the Photon board. It can only send one data point per second across Wi-Fi, which was substantially below the data rate that we needed for accurate readings. We encountered a frustrating 622 byte-per-message limit as well. As a result, we had to get creative with the reading of our data, so that we could capture the full spectrum of measurements that we needed!

Accomplishments that we're proud of

1) In only 36 hours, we managed to build a working electrical prototype out of a Particle Photon board with an OLED display and accelerometer.  A neat touch with our product is that we were able to use bitmapping to map our logo to the display, so that we can see our logo when it is turned on.

2) We have built a both a mobile and desktop UI, through which users can interact with their exercises and see their progress over time.

3) We built a working backend with Firebase that allows us to save and authenticate data and parse raw readings.

Overall, we have managed to create an entire prototype suite in the span of one and a half days!

What we learned

We learned that as much as we would like to, we can't add in every feature and every idea into a prototype. We sometimes had to backtrack on some minor features or tweaks to the code structure because doing so diverted our focus. As a whole, I think we can go into our next projects much more attuned to the most important aspects of prototyping new designs.

What's next for FLEX

We plan to make our website and mobile frontend more functional and user-friendly. We can also develop a hardware structure that makes our computing components smaller, more wearable, and more power-efficient.

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