Holographic optogenetic stimulation with calcium imaging as an all optical tool for cardiac electrophysiology

Abstract

All optical approaches to control and read out the electrical activity in a cardiac syncytium can improve our understanding of cardiac electrophysiology. Here, we demonstrate optogenetic stimulation of cardiomyocytes with high spatial precision using light foci generated with a ferroelectric spatial light modulator. Computer generated holograms binarized by bidirectional error diffusion create multiple foci with more even intensity distribution compared with thresholding approach. We evoke the electrical activity of cardiac HL1 cells expressing the channelrhodopsin-2 variant, ChR2(H134R) using single and multiple light foci and at the same time visualize the action potential using a calcium sensitive indicator called Cal-630.We show that localized regions in the cardiac monolayer can be stimulated enabling us to initiate signal propagation from a precise location. Furthermore, we demonstrate that probing the cardiac cells with multiple light foci enhances the excitability of the cardiac network. This approach opens new applications in manipulating and visualizing the electrical activity in a cardiac syncytium.

Multiple-image authentication scheme based on the phase-only holograms

“…Computer generated holograms (CGH) are widely used in different scientific and technological fields, such as biomedical field 10,11 , 3D imaging 12 , image encryption 13 , etc. The generation of CGH involves the computation of the diffraction field of the light sources on the surface of the object.…”