Wearable Hardware
    Completed
    2024

    Jaw Motion Counter

    Ultra-compact wearable device with a 4+2 rigid-flex PCB, ESP32, and MPU6050 sensor to track jaw motion and communicate via Bluetooth.

    ESP32MPU6050Rigid-Flex PCB (4+2)Bluetooth Low EnergyESP-IDFEmbedded CJTAG Debugging

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    The Challenge

    Fitting a fully functional jaw-motion tracking system into an AirPod-like form factor (20mm × 17.2mm, under 12g) required a 4+2 rigid-flex PCB to accommodate the ESP32 module, IMU sensor, antenna, and Li-ion battery in a single compact structure. Maintaining reliable Bluetooth connectivity with a custom 2.4GHz antenna on minimal ground plane area was a key RF design challenge, as was achieving a comfortable ear-worn fit while keeping the assembly robust enough for repeated daily use.

    Technical Overview

    A lightweight, ear-worn device weighing only 12g, designed to track jaw movements and communicate with a companion mobile app over Bluetooth. The system uses a 4+2 rigid-flex PCB measuring just 20mm x 17.2mm, integrating an ESP32 microcontroller, MPU6050 motion sensor, custom antenna, and rechargeable battery. Developed with ESP-IDF and Embedded C, the device was programmed via JTAG and designed to fit within a form factor similar to modern wireless earbuds.

    Key Features

    • 4+2 rigid-flex PCB design (20mm × 17.2mm)
    • Ultra-compact and lightweight — just 12g
    • Real-time jaw motion tracking with MPU6050 6-axis IMU
    • Bluetooth Low Energy connectivity to companion mobile app
    • Custom 2.4GHz antenna designed for minimal ground plane
    • Rechargeable Li-ion battery with onboard charging circuit
    • JTAG-based firmware programming and debugging
    • Form factor engineered to match an AirPod-style ear fitting

    Technical Specifications

    MicrocontrollerESP32
    Motion SensorMPU6050 (6-axis IMU)
    PCB Type4+2 rigid-flex
    PCB Dimensions20mm × 17.2mm
    ConnectivityBluetooth Low Energy (2.4 GHz)
    Firmware SDKESP-IDF
    ProgrammingJTAG
    PowerRechargeable Li-ion battery
    Weight12g
    Form FactorEar-worn, AirPod-like

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