Lumileds and BIOS partner to deliver more efficient circadian lighting

BIOS (Biological Innovations and Optimization Systems) LLC and Lumileds have jointly announced an efficacy breakthrough in solid-state lighting (SSL) systems intended to impact human wellbeing — technology often called human-centric lighting. Lumileds will supply BIOS and its BIOS Illuminated licensed partners with a new mid-power LED that delivers a significant energy peak at 490 nm in the cyan region. The new LED will result in a significant efficacy gain for BIOS SkyBlue-based systems during daytime operation.

Human-centric lighting, lighting for health and wellbeing, and circadian lighting are all terms used to describe spectrally-tunable lighting that changes over the course of a 24-hour cycle to match the needs of the non-visual receptors in the human eye. We have covered the non-visual system and the intrinsically photosensitive retinal ganglion cells (ipRGCs) for years and the fact the non-visual system is tied to alertness during the day and good sleep at night based on circadian entrainment that is reinforced by proper light exposure. You can get more background in an article that covered presentations made at our Lighting for Health and Wellbeing Conference 2018.

The simple story is that humans need blue-rich spectrum during the day and depleted blue energy at night. Of course, research continues in this area and there is much debate about the ideal circadian light spectrum. Most phosphor-converted white LEDs have a blue energy peak that comes courtesy of the blue pump that is the basis of the white LED architecture. Generally, that blue pump operates at around 450 nm where LED makers achieve the highest wall plug efficiency.

The BIOS secret sauce for human-centric lighting is custom spectral power distributions (SPDs), one for day and one for night, and tunable control to set the right SPD for the time of day. And most if not all researchers agree that 450-nm energy is not the wavelength that the circadian system and ipRGCs need to positively enhance wellbeing. BIOS calls its daytime spectrum SkyBlue and it features a significant energy peak at around 490 nm. The day and night SPDs are shown on the BIOS website in the circadian lighting section.

BIOS hasn’t revealed how precisely it has achieved the SkyBlue spectrum, but clearly there are multiple channels of LEDs involved. One issue with such a blue-rich SPD during the day is the efficacy penalty that such systems can exhibit. The human visual system has relatively low sensitivity to blue energy and thus the lumen per watt or efficacy metric can be quite low with human-centric technology.

BIOS and Lumileds expect the new SkyBlue LED to greatly improve efficacy for the human visual system while also providing for the non-visual daytime needs. Of course the partners won’t share full details, but we did learn that the LED does use a 490-nm pump and a proprietary phosphor formulation developed by Lumileds. That new LED, referred to technically as the BIOS supplemental LED (BSL), will be combined with standard warm-white LEDs in a tunable circadian system design. The BSL can be turned off at night, effectively eliminating blue energy from the SPD of a lamp or luminaire based on the BIOS technology.

Unfortunately, it’s hard to infer more about the architecture of the new LED and what exactly the SPDs of a system based on the new LED will look like exactly. Only BIOS and its licensees will get those details in specifications that will be released in Q1 2021 when the LED ships.

But what Lumileds and BIOS are touting in the announcement provides some clues. “We are able to double lumen output in our 3030 package and enable system performance to increase from 110 to 160 lm/W,” said Willem Sillevis-Smitt, head of marketing at Lumileds. “This can reduce the bill of materials, put utility rebates into play, and ultimately reduce end-user pricing.” That’s a significant system-level efficacy increase and it implies that the new SkyBlue LED does also produce energy at longer wavelengths through this aforementioned proprietary phosphor formulation.

The benefits could range from needing fewer LEDs in a product to hit a target output level to more easily qualifying products for rebates. Moreover, the system-level CCT can remain in the warm range. “This engineering and production partnership are what the industry has been waiting for,” said Mark McClear, COO of BIOS. “It will launch the next generation of human-centric lighting design.”

The technology could proliferate quickly. Today, BIOS itself offers SkyBlue replacement lamps and also a table lamp called SkyView. And the company has licensed its SPD and spectrum control technology to more than 20 partners in the BIOS Illuminated licensing program, with those partners offering a variety of products that integrate SkyBlue.

“Our partnership with BIOS enables us to address the growing demand for high-performance lighting solutions that support circadian health,” said Larry Chapin, senior product manager at H. E. Williams, a BIOS Illuminated partner. “The relationship BIOS established with Lumileds will strengthen the supply chain, resulting in reduced lead times and greater flexibility for their OEM partners.”

BIOS has been among the most vocal proponents for human-centric lighting for years. Company founder Robert Soler contributed a column about the prospects for such technology back in early 2019. Soler was also a member of our inaugural 40 Under 40 Class of significant contributors to the LED and SSL sectors announced this past summer.

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