Hi,
In most cases fc = 1 / ( 2 × Pi × R x C) applies.
R3, R4 act as a voltage divider, thus for C2 2.55k applies.
Choose fc to be very low, much lower than 10Hz.
C3 should be tge same as C7, with 470k as resistor for fc calculation.
Fc should be lower than 10Hz.
C4 and R8 determine the upper cutoff freqyency of the signal.
The same applies for C5 and R6.
R5, C6 determine the lower cutoff frequency of the signal,
Fc should be much smaller than 10Hz.
What frequencies to choose depends on the application...
Klaus