BLE Wearable Sensor: 14 Months on a CR2450 Coin Cell

Challenge: 12 months of continuous physiological monitoring from a CR2450 coin cell, with BLE connectivity and weeks of onboard data storage. Solution: Built around the nRF52832 with a PCB trace antenna (saves cost and board space at the expense of tighter impedance matching and ground plane tuning). Aggressive duty cycling: IMU wakes MCU on motion events, sensor sampling adapts based on activity level, BLE advertising intervals stretch during inactive periods. 64Mbit SPI flash for data logging between sync sessions. Results: Hit 14 months in accelerated discharge testing. The PCB antenna gets -68dBm at 3m, more than adequate for a wearable-to-phone link.