Accelerate Her Potential: Bolt Into Action!
Bolt is an accelerometer designed for female athletes that sparks one;s ability to crush performance goals, on and off the field.
Bolt is a comprehensive platform that combines intuitive and fun software with cutting-edge hardware.
With Bolt, you can seamlessly visualize your acceleration data,
gain personalized insights into your workouts, and turn your
performance goals into achievements.
Link to video on YouTube
Project Development
What did you design?
For my final project, I designed a 3-part system including the Bolt Sensor,
the Embroidered Bolt Top, and the Bolt digital platform.
All components & links are linked & can be found
in the resources tab.
What materials and components were used?
Bolt's involved materials and components sourced from Adafruit, Amazon, Harvard REEF, Michael’s Crafts,
and online platforms, with costs varying per item, such as the Adafruit Feather M0 ($19.95) and the BNO085 IMU ($24.95).
The 2D and 3D design processes included additive fabrication for a 3D-printed case with Harvard REEF PLA and subtractive
techniques like embroidery for the Bolt Shirt, while software tools like Arduino, Python, and VS Code were used to
program and integrate hardware components. Additionally, the digital platform utilized OpenAI API for processing and
Heroku for deployment, costing $5/month for basic usage.
Overall personal costs, given my access to Harvard & MIT resrouces:
For more details, visit Week 15: Product Development page!
Fabrication and Production
Bolt Sensor
The heart and sole of this project! The Bolt sensor integrates the Adafruit Feather M0 Adalogger (SAMD21 microcontroller), BNO085 IMU, MAX30102 pulsometer,
a 110 mAh LiPo battery, and a MicroSD card, all housed in a custom 3D-printed bolt case with magnetic connectors
and finished with purple metallic paint.
Components were sourced from Adafruit, Amazon, and local resources, with a total
cost of approximately $90. Using Arduino software for sensor control and Python code for data analysis,
the project successfully collected and evaluated motion and heart rate data, answering questions on system accuracy, real-time data logging, and sensor integration, while identifying areas for improvement in battery life and connection stability.
Microcontroller Selection
As someone who is new to working with electronics, the Adafruit Meather M0 was a great fit for my accelerometer. The Adafruit
Feather M0 is ideal as an intro sensor and for the Bolt Bra design because of its compact size (2.0" x 0.9") and lightweight
build (5.3g), making it perfect for wearable applications without adding bulk or discomfort.
Its SAMD21 microcontroller
offers ample processing power, native USB support, and built-in LiPo charging, enabling seamless sensor integration, real-time
data logging, and reliable performance—all critical for creating a user-friendly, functional wearable.
Arduino Code
I compiled & uploaded my acceleration code from Arduino. This sensor design was inspired by the Harvard course, the
Physics of Sports. By configuring the sensor with ALGMR (allecleration, linear acceleration, angular velocity, magnetoemter, and rotation)
we can decduct a variety of metrics such as acceleration, velocity, or cadence.
From there... PCB design time. WOW! This part of the project intimidated me. I had never even heard of a PCB, but after
many YouTube videos, trial / error, and long hours... KiCad, BitRunner, Mods, Roland SRM-20 CNC Machine... I started to love this process.
Conncting Sensors
All of my sensors used i2c connections, which was intuitvie to find the SLA/SCL ports. From not really knowing what the differnece
between microcontrollers (ESP32, RP2040, SAMD21... I had no idea!) The electronics were challenging but once I understoof the workflows,
they felt familar to the design software that I'm most familiar with,
After MANY variations, the Bolt sensor WORKS!
🔵 The blue blinks mean the sensor is being reset
🔴 The LED blinks red while a trial is being recorded
🟢 The LED blinks green when the user stops recording. The number of green blinks corresponds to the specific CSV file
🤓 Once your workout is complete, remove your microSD card, and upload your .csv files to your computer!
Bolt Case
50 case iterations.
The case design was one of the most challenging parts of the project.
Requirements:
Design phases:
- Mirrored Cases: You must mirror the cases! Duh. But upon first printing, I just made 2 identical prints of the lightning bolt. Well, well you are placing them on top of each other the must fit!
- Puzzle fit: I thought playing with one piece extruded +.2 inches and subtracted -.2 inches, that would be the winner. NOPE. I couldn’t make the whether it’s extruded or inverted, one of those components must be smaller than the other... because otherwise they won’t fit seamlessly.
- Perimeter magnet: OK... Making progress. However, this magnet design took up way too much area within the sensor, so I had to increase the size of the total case.
- Spot magnets: AHA! This is it. It extruded cylinders on the corners of the bolt case. The .125 inch circular magnetics fit beautifully. This secured bolt as you are on the move!
Bolt Bra
The embroidered top was SO much fun to design. I learned how to use Brother PE900 embroidery machine during Wildcard week, and
this is definitely a skill I will hold with me.
HTMAA introduced me to working with textiles, and I really enjoyed adding even a bit of personal flair to my design.
Bolt Box
I knew that there should be a custom way to enclose the Bolt Sensor and Bolt Bra, and I thought the wood
box would beautifully juxtabose the sensor technology and bra.
This box with hingest is 8x5x3". We use the Epilog Helix and Epilog Fusion Pro in the REEF. The box outlines are .001px.
Testing & Evaluation
Visit my deployed sites! CSV Data Analysis Deployed Site and ChatGPT Workout Deployed Site
Visualize your workout acceleration
Many data visualization tools are confusing, and don't explain data clearly. I used a Flask app & deployed with Heroku to make the data visualization process as simple as possible. Moving forward, I want to embed OpenAI insights into how to adjust your training baased on your data.
Reflect on your effort!
This site allows the user to share an insight, and receive some "words of wisdom" from the ChatGPT API. It actually was a
huge challenge working to get the API to connect to my app.py . From security preferences, API keys shutting off, to finding clear documentation,
I finally got the ChatGPT API to work. I'm proud of my deployed site (and definitely check it out!)
Can you tell I had fun deploying Heroku sites? Usually I'm used to jsut using Wix, but now I can OFFICIALLY call myself a software engineer! I really
love seeing code come to life in an enjoyable, and simple interface.
Closing thoughts
Overall, How to Make (Almost) Anything has been one of the most impactful expereinces of my academic career. Every Wednesday coming to the Media Lab, I felt challenged, inspired, and impowered. I am proud of this semester's learnings, and I cannot wait to see the incredible work my classmates do next!
Thank you Neil and our wonderful HTMAA teaching team for making this experience & project possible!
Resources & Documentation
Product Design
Fusion360 Lightening Bolt Case
Fusion360 Heartrate Monitor Case
Software
CSV Data Analysis Deployed Site
CSV Data Analysis Deployed Site
Ardunio Sensor Accelerometer Code
Harvard Physics of Sports Class
Electronics
MAX30102 Pulse Oximeter on Raspberry Pi Pico (RP2040)
Tutorial: Mods to mill circuits tutorial
Heart Rate Sensor Module MAX30102
Bolt Sensor KiCad Files: Schematic & PCB Design
Heartrate KiCad Files: Schematic & PCB Design
All KiCad Files: Schematic & PCB Design