Listen to your heart

A pair of earbuds from LG uses Valencell’s technology to capture heart rate and other biometric signals at the ear. The data can be sent on to a smartphone via Bluetooth from the wearable rectangular clip seen on the left. Credit: LG

PerformTek® sensor technology continuously and accurately measures weak blood flow signals even during extreme physical activity. The sensor module includes an optical emitter, an optical detector, specialized optomechanics, and an accelerometer. Credit: Valencell

There are quite a few of wristbands equipped with sensors to monitor your heart beats but now LG is looking at a different approach to monitor heart beats and other parameters. Using Valencell technology they are planning to sell earbuds embedding sensors that can monitor heart beats through photoplethysmography, a mechanism that uses the reflection of light caused by the blood flowing under the skin. When the heart beats there is a wave of blood rushing in the arteries and this slightly reddens the skin. A light shone on the skiing gets scattered in different ways depending on the quantity of blood and by detecting scattering differences a software can detect the beat. Additionally, the earbud sensors measure temperature and breathing rate.

Interestingly, the various parts of the ear provide different value of data and the software can analyse these differences to detect telling signs of different potential problems.

It is true that wristband "technology" is quite successful, in 2014 the estimate is to sell 17 million smart wristbands (that includes about 8 million smart watches), but according to LG the advantages offered by earbud sensing are compelling. The ear can provide many more data with greater accuracy, it is not moving as much as a wrist and we (at least part of us) are used to wear them for some time during the day. Using statistical analyses a hour per day, even split into shorter periods, is enough to derive accurate data.

Valencell technology, sold under the name of Perform-Tek, has achieved an amazing level of integration and miniaturisation. Photoplethysmography is not a new technology, it has been in use for several years now, but it required bulky apparatus. Valencell has been able to shrink it to fit an earbud. A weak point, though, is the need for power. Today the power is provided via an extra battery connected with a cable to the earbud, since draining on the same battery used by the earbud as a loudspeaker would drain it pretty fast.

Energy remains a major stumbling block for wearable devices and as I pointed out in a number of post the continuos decrease of power requirements by electronics can make scavenging of energy sufficient. In this case, however, the power requirement is still too high to be met by scavenging and it is going to remain so for several more years....

Author - Roberto Saracco

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