Embedded Firmware Engineer (Wearable, Multi-Sensor)

We're an early-stage health-wearable company building a comfortable, electrode-free ear-worn device that senses jaw tension (teeth grinding and clenching) using motion, mechanical, and optical sensors. We're building our first working prototype and need a firmware engineer to bring the sensor board to life. Scope of this engagement: Recommend/confirm a low-power MCU + BLE platform (e.g., Nordic nRF52/53 or similar) for an always-on wearable Write drivers and a data-acquisition pipeline for multiple sensors over I²C/SPI: an IMU (accelerometer/gyro), an optical heart-rate (PPG) front-end, and an analog mechanical/force sensor via ADC Tightly time-synchronize all sensor streams (critical for our detection logic) Stream/log raw, timestamped data over BLE to a computer for analysis Basic power management and a simple haptic (vibration motor) driver You're a great fit if you have: shipped firmware for a battery-powered wearable or IoT sensor device, comfort with multi-sensor I²C/SPI integration and sample timing, BLE experience, and the ability to deliver clean, documented code. Nice to have: experience with biosignal or health-sensor hardware (PPG, IMU-based activity, ECG/EMG, MEMS). Please share one or two past projects involving multi-sensor or wearable firmware, and a short note on how you'd keep several sensors sampling in sync. This is the first of several milestones with strong potential for ongoing work as we move toward a full prototype.