Evanescent field patterning for optogenetic activation

Evanescent waves are typically confined within a 100 nm-thick layer at the interface between two media with different indices. They are commonly used in fluorescence microscopy to enhance the signal-to-background contract when imaging cell membranes or for single molecule localization. For these applications, a homogeneous illumination is created the transverse plane. However, for applications to optogenetic photoactivation, it is desirable to create patterned evanescent waves. In collaboration with biologists from the Institute for Advanced Biosciences (IAB, Grenoble), we have developed a method for generating arbitrary evanescent patterns, using a wavefront shaping approach with a digital micro-mirror device (DMD). Photoactivation by evanescent waves leads to more intense and localized recruitment on the Cry2-CIBN optogenetic system in live cells.

References:

• Grosjean et al., Optics Express 32, 19480-19493 (2024).