Sensor
arrays used to detect electrophysiological signals from
the brain are paramount in neuroscience. However, the number of sensors
that can be interfaced with macroscopic data acquisition systems currently
limits their bandwidth. This bottleneck originates in the fact that,
typically, sensors are addressed individually, requiring a connection
for each of them. Herein, we present the concept of frequency-division
multiplexing (FDM) of neural signals by graphene sensors. We demonstrate
the high performance of graphene transistors as mixers to perform
amplitude modulation (AM) of neural signals in situ, which is used to transmit multiple signals through a shared metal
line. This technology eliminates the need for switches, remarkably
simplifying the technical complexity of state-of-the-art multiplexed
neural probes. Besides, the scalability of FDM graphene neural probes
has been thoroughly evaluated and their sensitivity demonstrated in vivo. Using this technology, we envision a new generation
of high-count conformal neural probes for high bandwidth brain machine
interfaces.