New sensors present options for under-display face biometrics on smartphones

Face biometrics have so far been supplied to Android mobile devices in the form of software that makes use of the front-facing camera, in contrast with Apple’s hardware-based 3D face scanning. That could soon change, however, with hardware image sensors emerging as possibilities for integration into smartphones and other electronic devices.

Metalenz has partnered with optoelectronic semiconductor firm Vertilite to launch the new Starlight projector for structured light applications.

Starlight is recommended for 3D face authentication on smartphones, gesture recognition, and automotive driver monitoring, among other applications. It provides high contrast suitable for indoor and outdoor lighting conditions, and is the most compact high performance, low cost structured light system for 3D sensing, according to the announcement.

Vertilite contributes its single-junction VCSEL (vertical-cavity surface-emitting laser) Dolphin, while Metalenz provides its Orion 18K pseudorandom dot pattern meta-optic projector.

“We believe the Starlight projector will further accelerate our market share growth in areas like biometric authentication, contactless access control, and robotics,” says Ryan Rao, CPO, Vertilite.

Metalenz signed a deal with Dilusense in July to bring 3D facial recognition to locks and payment kiosks.

Imec integrates PPD with thin-film sensor

Imec says it has successfully integrated a pinned photodiode with a thin-film image sensor for short-wave infrared (SWIR) imaging.

The use of thin-film absorbers like quantum dots has emerged as an alternative to the expensive III-V materials used in some absorbers, the company says. Combined with pinned photodiode (PPD) structures, the sensor avoids the problems with limited detection of silicon-based semiconductors and inferior noise performance from infrared sensors using thin-film technology, as explained in research results published in Nature.

The resulting sensor array can allow autonomous vehicles to see through fog or enable face biometrics on a smartphone, imec notes.

“At imec, we are at the forefront of bridging the worlds of infrared and imagers, thanks to our combined expertise in thin-film photodiodes, IGZO, image sensors and thin-film transistors,” says imec Program Manager for Pixel innovations Pawel Malinowski. “By achieving this milestone, we surpassed current pixel architectural limitations and demonstrated a way to combine the best performing quantum-dot SWIR pixel with affordable manufacturing. Future steps include optimization of this technology in diverse types of thin-film photodiodes, as well as broadening its application in sensors beyond silicon imaging. We are looking forward to further these innovations in collaborations with industry partners.”

OTI Lumionics selects self-assembling molecules

Canada-based OTI Lumionics has developed a way to hide 3D sensor arrays underneath the display of a smartphone using self-assembling molecules, reports TechHQ.

The company uses patent-protected technology called CPM Patterning (CPM stands for “cathode patterning materials”) to open up small windows in the display electrodes to let through infrared light.

Under-display smartphone face biometrics is one of the initial target applications for the technology.

The company began mass production of CPMs back in 2020 to serve the market for smartphone biometrics.

OTI Lumionics claims to have discovered the right materials for display electrode patterning by running algorithms inspired by quantum computing on traditional computers.

The TechHQ article notes anticipation by Apple-watchers that Face ID could move to under-display implementation in late-2024 or 2025.

OTI Lumionics also counts several display manufacturers like LG, Samsung, and United Display Corporation amongst investors in its $55 million Series B last year, so the technology may have several open paths to production.

Article Topics

biometrics  |  face biometrics  |  facial authentication  |  image sensor  |  imec  |  metalens  |  Metalenz  |  OTI Lumionics  |  smartphones  |  SWIR imaging  |  under display