Flick

Overview

During the summer of 2024, I was selected as one of 15 students for the six-week Apple Engineering Camp at Apple Park and Infinite Loop, where I attended classes across various consumer product engineering disciplines. Applying those learnings and my experience from FTC, I led the development of Flick with four other amazing team members. At the end of these six weeks, we pitched our product in a ten-minute keynote presentation to a board of Apple Executives, which included a live demo of the product.

Flick is a wrist posture monitoring device designed to help users maintain optimal ergonomics and prevent conditions like carpal tunnel syndrome by providing on-device feedback and delivering insights through an iOS app.

I was responsible for Flick’s hardware and electronics. The device was 3D-printed from a skin-safe TPE (Thermoplastic Elastomer) and ran off a 500mAh LiPo battery capable of providing all-day battery life. At its core, Flick utilized an Arduino Nano ESP32 to process data from two 6-DoF IMUs (BMI270s), which then communicated with our backend to provide insights to the user through the iOS App via Bluetooth.

Hardware

To say Flick underwent a couple of iterations is an understatement. Although there were six major versions, it was a priority to make sure to go down every avenue and test all the different form factors. The goal was to find a design that would be both wearable and comfortable while remaining non-obtrusive and still providing accurate tracking.

A key part of Flick was ensuring it returned only the relative angle between the individual’s hand and forearm to accurately determine their wrist angle, meaning at least two IMUs were a necessity. We explored multiple ideas, including combining the Apple Watch’s IMU with our own IMU on the hand, but decided against it, as many users might not own an Apple Watch. Flick was originally going to be a soft-good item (version 1). However, when accounting for the different sizes of people’s wrists and the need for breathability, I decided to go with a more lightweight, discrete, and 3D-printed TPE design.

The hexagonal lattice structure proved to be an unexpected benefit. I originally implemented the lattice for breathability, but it ended up being the perfect solution for adjustability as well. The securing hooks can latch into different hex cells, allowing the device to scale to various wrist sizes without needing separate parts or straps.

Flick provides on-device feedback through haptic patterns, which are controlled via a digital I/O pin on the Arduino Nano. Different patterns are used to communicate with the user, alerting them when their posture reaches an unhealthy range and reminding them to take corrective action.

Electrical

Flick’s final electrical layout is shown in the schematic above. A 5V USB-C buck converter (not shown on the schematic) was used to recharge the battery and regulate the 5V input to the Arduino Nano.

Gallery

Check out Flick’s CAD here!