A method for detecting in a bio sensor misalignment between the bio sensor and a bio signal receiving module is provided. The method includes receiving, by the bio sensor, a light signal from the bio signal receiving module, determining, by the bio sensor, whether the light signal is received in a misalignment detection section, determining, by the bio sensor, that the bio sensor and the bio signal receiving module are misaligned if the light signal is received in the misalignment detection section, generating a feedback signal that comprises information to indicate misalignment between the bio sensor and the bio signal receiving module, and transmitting, by the bio sensor, the feedback signal to the bio signal receiving module.
