Opti4 Optical Heart Rate Module


The highly integratable, future-ready optical heart rate (and more) solution.

The Opti4 module allows for a deep integration into a wearable device’s architecture, utilizing the mcu and accelerometer on the device’s main board for integration of the Bioprobe software library, providing greater flexibility.

The Opti4™ is part of the expanding Bioprobe™ platform, and consists of a hardware side – the unique optical head with an integrated, custom Analog Front End (AFE) – and a software side – the ARM®-based Bioprobe library supporting optical heart rate with motion artifact correction, with additional monitoring software options available.  This architecture enables developers of wearables to minimize size and resources by leveraging their devices’ existing ARM®-based MCU and motion sensor.

The Opti4 contains a unique, proprietary optical architecture that consists of four high resolution optical detectors surrounding a single probe beam, enabling high performance heart rate acquisition with a low power capability.  This system maximizes both the amount of photons reaching the skin from the single probe beam and the quantity of reflected photons being detected.

In any optical heart rate monitoring system, not all the photons from the emitter(s) reach the skin and of those that do, some are absorbed, some scattered and the rest are reflected in all directions within the microvascular bed in the human tissue.  Only a portion of these photons are collected by the detector assembly.

Opti4’s optics maximizes the amount of photons reaching the skin and the quantity of reflected photons detected, resulting in high resolution and ratio of heart signals to noise.

Accurate continuous heart rate

Opti4’s utilizes proprietary high resolution architecture and algorithm set that efficiently detects and processes optical heart rate signals.  It also integrates motion artifact compensation, cardiac model adaptive filtering and heart rate computation techniques. This unique design results in both high accuracy and low power.

Modular software library/ Future-proof design

The ARM® MX based Bioprobe software library also includes optional monitoring modules (activity tracking, calorie-burn estimation, sleep monitoring, heart rate variability analysis, and more) so multiple devices can be customized and offered with the same Opti4 hardware.

Enabling these modules only requires leveraging hardware already on the host, such as the MCU, sensors and memory.  So, one hardware solution for now and in the future. 

Analog front end

  • Unique high resolution optical detection and ambient light rejection
  • Proprietary low power, high signal to noise amplification and conditioning

PPG and optics

  • Patented optical architecture
  • Four detectors surrounding one LED
  • Advanced optical lens assembly
  • High optical coupling efficiency


  • 10.4mm x 12.9mm, 2.5mm thickness (effective 1.75mm thickness when integrated into device’s case back)
  • 8 pins total
  • Communication interface: I2C