CEA-Leti shows microLED-based biosensing system
CEA-Leti has demonstrated a co-packaged microLED and organic photodetector (OPD) architecture with both devices optimised for operation at green wavelengths relevant to bio-sensing; in particular photoplethysmography (PPG) signal extraction.
PPG is a non-invasive optical approach for detecting blood volume changes, for instance to measure blood oxygen saturation and to monitor heart rate in patients at rest.
The work, presented in the Photonics West paper 'Co-Packaging of Organic Photodetector with MicroLED Matrix for Multifunctional Display Bio-Application', validates a system-level approach combining device design, electronics, and modelling for multifunctional display applications.
MicroLEDs deliver high radiance using only a limited fraction of the pixel surface, leaving space for added functions – which in this case was the specially designed OPD.
The researchers designed a dedicated electronic platform enabling full end-to-end characterisation of the complete signal chain— from microLED driving, through a device under test, to photodetection and readout circuitry. Lock-in detection techniques were implemented to improve signal-to-noise ratio and suppress static parasitic components.
The co-packaged microLED devices demonstrated optical power up to 12 mW at a wavelength of 525 nm. On the detection side, OPD responsivity was tuned by adjusting the thickness of the ZnPc active layer to align with the microLED emission peak, achieving a responsivity of 0.083 A/W at the wavelength of interest.
The results show that microLED displays can support integrated optical sensing at the pixel level without forcing trade-offs between brightness, resolution, and sensing area. Unlike OLED-based approaches, where display and sensing functions compete for the same surface, this architecture allows both functions to coexist within the same front plane.
Rather than relying on sensors located usually in the bezel of the display, this approach enables sensing capabilities to be designed directly into the display and widespread.
“This work illustrates CEA-Leti’s system-technology co-design approach, from concept definition and microLED technology to photodetector co-design, electronics development, and experimental validation under realistic conditions,” said Michaël Pelissier, lead author of the paper. “By combining hardware development with analytical modeling and simulation, we establish a concrete framework for evaluating and scaling sensing-integrated display architectures.”
CEA-Leti says the architecture can be adapted to different pixel pitches and resolutions, depending on the targeted application—from medium-size displays such as smartphones and wearables to larger formats including monitors and televisions.
This work is part of the IPCEI Microelectronics and Connectivity and was supported by the French Public Authorities within the frame of France 2030.
