ActLight’s Ultra-Small Size and Low Power Consumption Make It Ideal for Heart Rate Monitoring in Hearables

ActLight DPD
Image: ActLight (PRNewswire photo)

Wearables aren’t just something that you wear around your wrist anymore. Hearables – a new type of wearables – are becoming popular. Hearables are smart electronic in-ear-devices designed for wireless communication, health monitoring and fitness tracking. These devices also can translate languages in real time and can be operated via voice command.

For vital signs monitoring, hearables require tiny sensors with long battery life and precision measurement capabilities.

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ActLight, founded in 2011, is a Lausanne, Switzerland-based startup that develops disruptive technology in the field of light sensors. The company has developed a heart-rate sensor based on dynamic photodiode (DPD). The ActLight Dynamic Photodiode consumes about 20 percent of the power of commercial devices, making it an ideal candidate for hearables.

The absence of an analog amplifier improves the signal-to-noise ratio of the DPD, which translates in higher output signal accuracy.

ActLight’s 100% owned, patented CMOS-based photonics technology allows to substantially improve the efficiency and accuracy of various light sensing applications in the Internet of Things (IoT) space, like Time-Of-Flight (TOF) based distance measuring (i.e. user detection, gesture control and visual recognition), vital signs monitoring, 3D/2D cameras and much more. ActLight operates in markets like mobile and wearable devices, healthcare/medtech, autonomous driving, drones and robotics.

A light sensor
Image: ActLight (YouTube)

Despite ultra-small detector area (<0.2mm2) and minimal LED power (<1uW/Hz), the sensor delivers convincing >70dB SNR. In addition, the ActLight solution provides a very strong output signal without AFE, further reducing the power consumption of the overall system, says a press release.

Typically, wearables use photoplethysmography (PPG) to measure pulse and oxygen uptake in the blood by measuring the amount of light reflected back from blood flowing in an artery. However, the bright light used in the technology is responsible for draining batteries. DPD can reduce the required light power by 80%, according to ActLight.

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The Dynamic PhotoDiode is the vital signs monitoring sensor of choice to meet the very demanding technical requirements of the hearable devices market.