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Smart Coaster

Overview: During HackDuke's 24-hour hack-a-thon for good, my team developed a drink coaster that tracks water consumption and sends hydration reminders via SMS.

 

You can check out our official submission at: https://devpost.com/software/smart-coaster.

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Our team consisted of 5 sophomore students at Duke University (the middle 5 in the picture to the left):

  • Shaan Narayan (me!)

  • Patrick Hardison

  • Ajay Krishnamurthy

  • Anthony Fernando

  • Ryan D'Cunha

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Throughout the 24 hours, we had to rapidly prototype and iterate to arrive at our end product. On the physical side of the Smart Coaster, we had trouble converting the seemingly erratic force-sensing resistor measurements into accurate readings. To combat this problem, we brainstormed ways to consistently distribute the weight of our water bottle across the resistor. What started with using a pizza saver eventually turned into a 3D-printed plate that measured the amount of water in the bottle accurately. We also printed multiple iterations of the chassis to incorporate more features such as the LEDs and housing for the particle photon microcontroller.

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The physical part of our product includes a PLA housing that contained our internal hardware. The housing was designed in Solidworks and printed as three parts: a top, a bottom, and a middle piece to consistently distribute the bottle's weight across our sensor.

 

We used a Particle Photon microcontroller because of its Wi-Fi capabilities, a force sensing resistor (FSR) to measure the weight of the bottle, and a string of parallel LEDs to assist as another form of user communication.

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To convert the sensor reading into a measurable liquid volume, we took several data points and used linear regression to find the optimal conversion. In our code (C++), we programmed our Photon to take a sample of the FSR data to determine how much water has been consumed.

 

If our code determines that the user hasn’t had enough water, the Photon will send a text message to the user using Twilio’s SMS API and webhook and pulse the LEDs until they grab the bottle to drink.

The end product was incredibly successful, and the whole event was a great memory for me and my friends. In the end, our product won three awards:​

  • Health and Wellness Track: 2nd Place

  • Novice Award: 1st Place

  • Twilio API Award: Most creative use of the Twilio API

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