Pupilometer — Ganglion Med-Tech

Ganglion is a startup working to create a low-cost pupilometers for hospitals using the cameras on smartphones to compete with the current overpriced monopoly. A pupilometer measures the size of one's pupil and how it reacts to light, allowing quick diagnosis of concussions, brain bleeds, and other critical injuries. Unfortunately, a phone camera alone doesn't have the accuracy needed for medical measurements.

I was hired to create a hardware clip-on for phones that solves many of these problems in preparation for a clinical trial later this year.

• Macro Lens Clip On: Designed a phone clip that improves smartphone camera with a macro lense for precise pupil measurments
• Ambient Light Sensing: Luxometer to measure external light conditions and calibrate pupil response.
• External Lighting: External light source to stimulate pupil that dynamically changes depending on ambient lighting.
• Bluetooth Connectivity: Wireless communication with smartphone app to recieve data / trigger actions over BLE.

The project utilized a SEEED ESP32 microcontroller, 1200 mAh LiPo battery, and perfboards with sensors / LEDs / buttons soldered on. After testing various light sensors against clinical luxometers, we settled on a simple Adafruit VEML 7700 for it's dynamic range.

Biggest Challenges:

• Fitting all the nececssary electronics in a small for factor while maintaining a robust system, especially whithout the lead time neccessary for a traditional PCB approach.
• Allowing easy disassembly to quickly iterate different components rather than gluing/potting all the electronics in place.
• Ensuring low power draw while to allow for a full week powered wihtout charging.

Solutions:

• I separated the electrical components into 3 perf boards, with JST connectors between them for compactness with robust connections.
• I designed custom clip-on mechanisms that securely hold all components in place without permanent adhesives.
• I used the ESP32's deep sleep functionality when not in use and used a new opensource BLE library for low energy consumption.

To finish my work with Ganglion I submitted a final prototype integrating all the feedback from the inital round of testing with health care professionals. The