Devices and methods for detecting a medical sensor device being attached to a host device are disclosed. The host device includes a reader circuit that can generate an AC pilot signal. When the medical sensor device is being attached to the host device, the AC pilot signal is fed to a non-linear circuit in the sensor device, which responds with a DC signal. The host device compares the magnitude of the response signal with a threshold magnitude. If the magnitude of the response signal is greater than the threshold magnitude, the host device determines that the sensor device is being attached and establishes connection with the sensor device.
