Personal Project: Wearable Bionode
Status: Schematics in progress
A wrist-worn autonomous emergency health beacon and continuous health monitor. On a two-board 30x30mm HDI stack (8-layer main, 6-layer sensor), it captures ECG, SpO2/HR, and EDA, and is designed to send a GNSS-tagged distress alert over satellite LoRa with no cellular coverage required.
The design centers on a low-noise biopotential analog front end: an ADS1292 AFE for ECG with an active Right Leg Drive to maximize CMRR, a separate PPG path for SpO2/HR, and pi-filtering verified in LTspice. The board runs a distributed power delivery network with dedicated analog and digital rails to keep switching noise off the sensitive front end, and a 3-stage medical defibrillation and ESD protection front end on the electrode inputs, also verified in LTspice.
The system is built around an nRF54L10 MCU with tri-band RF (BLE, satellite LoRa, and a GNSS module for location), an IMU for motion-artifact rejection, and NOR flash for on-device logging. It is a personal project to push my analog, RF, and high-density mixed-signal design past what my other work has required.
ECG Front End
PPG Front End
PMIC
PMOLED
IMU
Fuel Gauge
