MAXREFDES103#: Wrist-Based SpO2, HR, and HRV Health Sensor Platform

The MAXREFDES103# is a wrist-worn wearable form factor that demonstrates the high sensitivity and algorithm processing functions for health-sensing applications. This health sensor band platform includes an enclosure and a biometric sensor hub with an embedded algorithm for heart rate and SpO2 (MAX32664C) which processes PPG signals from the analog-front-end (AFE) sensor (MAX86141). Algorithm output and raw data can be streamed through Bluetooth® to an Android® app or PC GUI for demonstration, evaluation, and customized development.

Design files, firmware, and software can be found on the Design Resources tab. The board is also available for purchase.


  • Photoplethysmography (PPG)
  • Wrist-based embedded heart rate, blood oxygen saturation (SpO2) algorithm
  • Heart rate variability (HRV), respiration rate, sleep quality library algorithm
  • Wearable health band form factor
  • MAX32664 sensor hub
  • MAX86141 PPG analog front-end
  • 3-axis accelerometer
  • Windows® and Android GUIs


  • Wearable sports watch
  • Healthcare tracker
  • Heart signal data tracker

How to Quickly Measure SpO2, HR, and HRV Blood from Your Wrist Using the MAXREFDES103
3:45 June 04, 2020

How to Get Your Healthcare Wearable Off the Ground Faster
1:45 June 10, 2020

MAXREFDES103# Enlarge+


The MAXREFDES103# contains enables quick evaluation of our hardware and embedded firmware for heart-rate and SpO2 monitoring on a wrist-based platform to significantly shorten development time for custom fitness, health, and clinical applications.

The MAXREFDES103# platform includes the following key components

  • Micro board, which includes the MAX32630 microcontroller, MAX20303 power-management IC (PMIC), dual-mode Bluetooth, and 6-axis accelerometer and gyroscope
  • Sensor board, which includes the MAX86141 AFE, optical heart-rate sensor with one green LED, one red LED, one IR LED, two photodiodes, and MAX32664C biometric sensor hub with an embedded algorithm for heart rate and SpO2 monitoring
  • MAXDAP Pico Adapter board for use during a firmware upgrade for the micro board
  • Health sensor band enclosure and straps
  • Hardware design files, firmware, and software

System Diagram

Figure 1. MAXREFDES103# system diagram.

User Guide

Required equipment

  • PC or Android device (e.g., tablet) with Bluetooth connection for data logging

Android is a registered trademark of Google Inc.
Arm and Cortex are registered trademarks of Arm Limited.
Maxim is a registered trademark of Maxim Integrated Products, Inc.
The Bluetooth word mark and logos are registered trademarks owned by Bluetooth SIG, Inc.
Windows is a registered trademark of Microsoft Corporation.

User Guide

Required equipment

  • PC or Android device (e.g., tablet) with Bluetooth connection for data logging

Download, read, and carefully follow each step in the MAXREFDES103# User Guide.

All Design Files

Download All Design Files

Hardware Files:

Each file includes schematic, BOM, PCB layout, fab package, and PCB CAD


Ultra-Low Power Biometric Sensor Hub

  • Biometric Sensor Hub Enables Faster Time to Market
  • Finger-Based (Version A) Algorithms Measure
  • Wrist-Based (Version B) Algorithm Measures:

PMIC with Ultra Low IQ Voltage Regulators, Battery Charger and Fuel Gauge for Small Lithium Ion Systems

  • Extend Battery Use Time Between Battery Charging
  • Easy-to-Implement Li+ Battery Charging
  • Minimize Solution Footprint Through High Integration

Best-in-Class Optical Pulse Oximeter and Heart-Rate Sensor for Wearable Health

  • Complete Single-Channel, Optical Data Acquisition System
  • Optimized Architecture for Transmissive and Reflective Heart Rate or SpO2 Monitoring
  • Low Dark Current Noise of < 50pA RMS (Sample to Sample Variance)

Ultra-Low-Power Arm Cortex-M4 with FPU-Based Microcontroller (MCU) with 2MB Flash and 512KB SRAM

  • High-Efficiency Microcontroller for Wearable Devices
  • Power Management Maximizes Uptime for Battery Applications
  • Optimal Peripheral Mix Provides Platform Scalability

Quad SPDT Audio Switches

  • Low On-Resistance (0.61Ω typ)
  • 0.06Ω (typ) Channel-to-Channel Matching
  • 0.32Ω (typ) On-Resistance Flatness