Home-monitoring is a vital part of symptom management for patients with chronic diseases. Specifically, many heart failure have to balance self-management of medications and lifestyle in adjustment with their symptoms. Peripheral edema is an easy, indicative measurement that correlates with many worsening progressive events of heart failure, but there is a lack efficiency and standardization in measuring this symptom. We aim to create a comfortable wearable device that quantitatively monitors ankle edema for at-home monitoring.

What it does

Aquell is a wearable ankle band with a flexible sensor, wireless battery, and bluetooth data transmitting device that can be worn by patients at home. When it reaches a specific and tailored level of expansion sensed in the sensor, Aquell will send a notification to our smartphone app which asks patients a series of health questions and medically approved advices for next steps of symptom management.

How I built it

The key component of the device is a cheap piezoresisitve rubber cord, which changes resistance as it is stretched. This allows it to be used as a length sensor. We wrapped this around a compression wrap (for sprains) and sewed it in. This is soldered to a simple voltage divider attached to a bluetooth enabled microcontroller (Adafruit BlueFruit). This pushes the sensor signal to an iPhone allowing us to read circumferential changes. We tested it by inflating a balloon while recording data, as well as inflating a balloon slightly on a human arm.

Challenges I ran into

It is tricky to sew microcontrollers and sensors into a stretchable fabric. Had to stabilize the area where the electronics were mounted by sewing in a piece of non-stretchable plastic bag beneath, so the area would not locally stretch. There was also some trickiness in getting a non-noisy signal from attaching the rubber band to the circuit, with epoxied alligator clips :P.

Accomplishments that I'm proud of

We are proud to have made a physical, wireless working prototype in less than 24 hours along with ensuring data collection.

What I learned

It was our first time using a bluetooth microcontroller so figuring out serial communication was tricky but cool to see. We learned more about the severity and prevalence of heart failure and the importance of symptom monitoring. Also learned to consider the patient perspective of management of chronic diseases.

What's next for Aquell

We hope to get Aquell into the clinic for study trials where heart failure patients and physicians are able to test out the convenience and effectiveness of the device. Aquell can also be used for research purposes for clinicians to be able to quantify peripheral edema in correlation with emerging symptoms. Finally, Aquell can be used for more than just heart failure as peripheral edema can also be indicated as a warning sign for patients with chronic kidney disease or diabetes.

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