Heart rate monitor for wearables has ultra-low power consumption
Among wearables such as sports bands and smart watches pulse sensing capability has become mainstream, with new functions continually being added. However, their limited battery capacity makes it necessary to reduce power consumption as much as possible to prolong operating time.
In response, Rohm utilizes optical sensor development expertise and IR removal technology to develop an optical sensor for heart rate monitoring optimized for wearables that meets market needs for low power consumption and high accuracy. An optical filter enables high accuracy detection, extending battery life while reducing the effects of IR rays by 10x vs conventional products, claims Rohm. This makes it possible to acquire high quality pulse signals even in environments with strong IR presence, such as outdoors, or under intense movements (i.e. sports).
A photodiode matched to the green wavelength ideal for pulse detection is used, along with a filter structure optimized for pulse detection that integrates green and IR cut filters in the receiver block. As a result, high accuracy is achieved while susceptibility to IR rays reduced by 10x compared with conventional products, enabling stable pulse detection even under noisy IR conditions such as direct sunlight or strenuous activity.
The BH1790GLC is capable of detecting high quality pulse signals using low VF low brightness LED elements, eliminating the need for DC/DC circuits for LED power supply conventionally required. This decreases mounting area by 30%, lightening development load.
For developers, an optical heart rate monitor expansion board (BH1790GLC-EVK-001) is available that can collect and process sensor information by connecting to an open platform (general MCU board) such as Arduino Uno.
More information: https://www.rohm.com/web/global/sensor-shield-support/heart-rate-sensor
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