Si1144 optical sensing module,
Reduces the cost and complexity of wrist-based heart rate measurement


Silicon Labs announced the release of an optical HRM sensor solution designed to reduce cost and complexity in wrist-based heart rate monitoring (HRM) applications. Silicon Labs stated that the solution includes a low-power optical sensor module and an energy-friendly EFM32™ Gecko microcontroller (MCU) running advanced HRM algorithms. The small-footprint Si1144 sensor module features an optical sensor, a green light-emitting diode (LED), an LED driver for up to two external LEDs, an analog-to-digital converter (AD converter), control logic, and an I2C digital interface.

According to market forecasts by Silicon Labs, 100 million HRM-enabled devices will be sold by 2018, and most of these will be wrist-measuring wearables. Silicon Labs' Si1144 HRM solution targets the rapidly growing market for a wide range of wearable devices, including activity tracking fitness bands, pedometers, and smartwatches, as well as application markets where HRM functionality is added to fitness center equipment, bathroom scales, and activity monitoring devices for the elderly.

Heart rate monitoring is one of the most popular biometric sensing technologies available to everyone, from passionate athlete-level users seeking to improve their exercise records to the general public pursuing a healthier and more active lifestyle. Accurate HRM enables precise calorie calculations, making it easier to manage your diet for weight management.

In traditional methods, heart rate measurement has been limited to using chest straps connected to external devices, such as specialized fitness watches or smartphones. These types of HRM solutions have drawbacks, including being cumbersome and uncomfortable to wear, and the difficulty of monitoring via smartphone while running or cycling.

Wrist-based HRM technology has transformed biometric monitoring methods by providing a more convenient and comfortable way to measure heart rate with precision comparable to chest-strap-based products. Amidst many HRM solutions, measurement results vary significantly depending on the specific unit, and not only are they expensive, but they also consume a lot of power, shortening battery life. In addition, complex noise effects caused by movement are a major headache in the design of wrist-measuring HRMs.

Daniel Cooley, Vice President of the IoT Products Business Unit at Silicon Labs, said, “An additional benefit of Silicon Labs’ HRM solution is its industry-leading power consumption and very small footprint, making the Si1144 module an excellent choice for power-sensitive and space-constrained wearable devices.”