Wireless power transfer system

A method of operating a wireless power transfer system, the wireless power transfer system comprising:

• one or more primary coils for generating an oscillating electromagnetic field for wirelessly transferring power to one or more secondary coils;
• one or more emitting coils for generating an electromagnetic field for exciting a nuclear quadrupole resonance in the biological material of an animal exposed to the electromagnetic field generated by the one or more emitting coils;
• and
• one or more detecting coils for detecting the absorption and/or emission of electromagnetic radiation by and/or from the excitation of the nuclear quadrupole resonance;
• wherein the method comprises:
• generating an electromagnetic field, using the one or more emitting coils, for exciting a nuclear quadrupole resonance in the biological material of an animal exposed to the electromagnetic field;
• detecting the absorption and/or emission of electromagnetic radiation, using the one or more detecting coils, by and/or from the excitation of the nuclear quadrupole resonance;
• and
• preventing the one or more primary coils from generating, or causing the one or more primary coils to reduce the amplitude of, the oscillating electromagnetic field when the one or more detecting coils detect the absorption and/or emission of electromagnetic radiation by and/or from the excitation of the nuclear quadrupole resonance in the biological material of an animal.

A system for detecting the presence of an animal comprising:

• one or more emitting coils arranged to generate an electromagnetic field for exciting a nuclear quadrupole resonance in the biological material of an animal exposed to the electromagnetic field generated by the one or more emitting coils;
• and
• one or more detecting coils for detecting the absorption and/or emission of electromagnetic radiation by and/or from the excitation of the nuclear quadrupole resonance;
• wherein the system is arranged, when the one or more detecting coils detect the absorption and/or emission of electromagnetic radiation by and/or from the excitation of the nuclear quadrupole resonance in the biological material of an animal, to generate a signal.