by Mat Dirjish
CEA-Leti, a technology research institute focusing on miniaturization technologies, demonstrated a co-packaged microLED and organic photodetector (OPD) architecture at Photonics West that it claims will enable optical sensing functions. According to CEA, this architecture forecasts the ability to integrate sensing capabilities directly within a microLED display without compromising display performance. A paper titled “Co-Packaging of Organic Photodetector with MicroLED Matrix for Multifunctional Display Bio-Application”, validates a system-level approach combining device design, electronics, and modeling for multifunctional display applications.
As per CEA, microLEDs deliver high radiance using a limited fraction of the pixel surface, leaving space for additional functionality. Leveraging this characteristic, CEA-Leti developed a microLED array co-packaged with a tailored OPD, with both devices optimized for operation at green wavelengths relevant to photoplethysmography (PPG) signal extraction.
Moving beyond component-level demonstrations, CEA researchers designed an electronic platform enabling full end-to-end characterization of the complete signal chain from microLED driving, through a device under test, to photodetection and readout circuitry. They used lock-in detection techniques to improve signal-to-noise ratio and suppress static parasitic components.
The researchers used special optical phantoms that replicate the absorption and scattering properties of biological tissue to validate the system. Allegedly, this approach provides a controllable and repeatable environment for assessing biosensing performance under realistic conditions.
The co-packaged microLED devices deliver optical power up to 12 mW at a wavelength of 525 nm. On the detection side, OPD responsivity tuning is via adjustments to 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.
Summarily, 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.
For deeper insights, procure and peruse the Co-Packaging of Organic Photodetector with MicroLED Matrix for Multifunctional Display Bio-Application research paper. Also visit the CEA-Leti website.
Mat Dirjish Online 