Next-level light detection with Black Silicon

The use of photodiodes to sense reflected light has been a gamechanger for non-invasive health monitoring in wearable applications. But with battery life a constant topic of discussion, ElFys’ Black Silicon is a new technology that could really shake things up…  

ipXchange discovered a very interesting technology at SENSOR+TEST 2024 in the form of ElFys’ patented Black Silicon technology. As Dr. Toni Pasanen explains, ElFys’ Black Silicon enables photodiodes with the highest sensitivity available on the market.

The difference with ElFys’ photodiodes is that the Black Silicon technology captures over 50% more light than existing photodiodes. It does this by using a unique forest-like silicon nanostructure that greatly reduces any reflections of incoming light. Hence, it looks black.

This makes ElFys photodiodes great for applications where every ray of light counts, such as health monitoring using green light. You may have seen this on the back of your smart watch with an LED and photodetectors to capture the green light reflected off your skin for heartrate and spO2 (oxygen saturation) measurement.

But with so much more light captured than standard photodiode technology, ElFys enables you to achieve far more accurate readings, as well as insights that were previously not possible.

Toni then shows us a live demonstration of ElFys’ Black Silicon versus a standard photodiode for green light detection in your typical wearable application. As you can see, there is a much higher signal received by the Black Silicon device, meaning that it is much more sensitive and can therefore give you more insights into user health.

Alternatively, Black Silicon enables you to reduce the supply current to the green LED so that you can extend the battery life of your wearable. Or, you can reduce the size of the sensor, which makes Black Silicon great for smart rings!

Toni’s colleague Mikko then shows us this technology in action as it monitors his heartrate through his finger. As you can see again, his pulse is much clearer on the Black Silicon measurement due to the higher sensitivity.

Learn more about ElFys’ Black Silicon technology and photodiodes for wearable applications by following the link to the board page below, where you can apply to evaluate the technology for use in your commercial applications.

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