Recently, organic light-emitting diodes (OLEDs) have gained increasing interest as light source for biophotonic applications. Especially in the context of wearable and implantable electronics, OLEDs are particularly interesting due to their mechanical flexibility, the possibility to form densely patterned microscopic pixels, to achieve fast response time, and to tune the emission properties. In addition, OLEDs allow stacking of individual pixels, which enables multi-color light emission from exactly the same area. In this contribution, we present our recent progress on tailoring OLED properties for use in optical stimulation of cells by means of optogenetics. With the development of light-sensitive proteins capable of both activating and inhibiting cellular activity using two different stimulation wavelengths, light sources are required that provide switchable bi-color light emission. We developed two-terminal, bi-color OLEDs that are capable of switching the emission color by changing the applied voltage polarity and show how these can trigger bidirectional photocurrents in ND7/23 cells and elicit electrical activation and silencing of neuronal activity in fruit fly larvae.
|