We present a new method to acquire label-free multidimensional information from optogenetically engineered cells using a graphene transistor. Using a graphene fi lm to form a densely packed layer with cells, some important cellular optogenetic information was precisely detected and cells expressing diff erent channelrhodopsin-2 variants were eff ectively distinguished. The study off ers a general detection method of multicellular information that extends the application of optogenetics in neuroscience and provides a novel sensor for the development of future biological prosthetic devices.