​Biologists have been looking for ways to use OLEDs as integrated light sources in cell cultures for a while. However, doubts as to the potential impact of the devices on bacteria and other cells remained—especially given that OLEDs contain materials like silver, known for its antibacterial properties. Researchers at Leti, a CEA Tech institute, joined forces with LMGP* to demonstrate, for the first time ever, that OLEDs are fit for use with biological materials. 

The researchers used innovative devices that only Leti possesses: "Top emission" OLEDs encapsulated with thin barrier layers deposited using ALD (atomic layer deposition). The OLEDs, fabricated on a silicon substrate, emit light from the top, rather than from the bottom like conventional "bottom emission" OLEDs. The "top emission" design prevents the light emitted from being guided through the substrate, doing away with the resulting noise in the process. In addition, the design brings the distance between the light source and cells down from 1 mm to less than 1 micron.  

When placed near cell or bacterial cultures, the OLEDs did not disrupt growth. In fact, growth was comparable in every way with the growth of non-illuminated cultures. In parallel, additional testing showed that the OLEDs protected with a conventional packaging layer were not damaged by contact with the biological solution.

The research will create new opportunities for OLED matrices in biology. A patent protecting the devices' use for this application is in progress.

*The CNRS and Grenoble Institute of Technology Materials and Physics Engineering Lab