Chopper Amplifier - Design difficulty

Hi All,

I am designing an amplifier for extra-cellular neural recording. The input is given to a OSFET differential pair (M1 and M2 - input transistors). All the materials above the gate-oxide of the OSFET sensor is removed and exposed to the buffer solution where the neuron is kept. The gate voltage is set by using an electrode immersed in the buffer solution. The stimulating pulse is delivered through another twisted wire. When the neuron generate action potential , signal pass through the buffer solution and be detected by M1. For the OSFET differential pair, M2 is used to cancel the common noise in the buffer solution, the other one is used to sense the neural signal.

I need to remove the 1/f noise using chopper technique. According to OSFET sensor described above, I can't isolate the neural signal before reaching M1.
My question is: Is there a way to implement chopper technique here so that I can modulate the neural signal before it mixes with 1/f noise?

Thanks in advance