In this work,we propose a schematic design for the biochemical sensor,which is based on the polyatomic photonic crystal ring resonator(PCRR).Unlike with the conventional approach,the proposed PCRR is constituted by two different branching waveguides(WG),which are all in the same lattice direction but have different optical propagation properties due to the binary nature of the diatomic square lattice.Electromagnetic analysis via PWE and FDTD numerical techniques are employed to investigate the sensing performance and the results show that the proposed sensor can efficiently detect the small changes in the re-fractive index of sensing area.