A method for eddy current induction detection comprises: providing an excitation signal to a first coil; the first coil generates a first electromagnetic signal due to the excitation signal; the first electromagnetic signal is coupled to a second coil, and causing the second coil to generate a second electromagnetic signal; when a target conductor receives the first electromagnetic signal or the second electromagnetic signal, the target conductor will generate an induced eddy current, the induced eddy current at least partially offsets the second electromagnetic signal of the second coil; and measuring the change in the second electromagnetic signal after at least partial cancellation through the second coil to determine the state of the target conductor. |