Patent ID: 8139306

Claim:
A testing method, consisting of: positioning a magnetic read/write head above a magnetic storage medium at a flying height wherein said magnetic read/write head and said magnetic storage medium act as opposite plates of a capacitor wherein a spacing between said magnetic read/write head and said magnetic storage medium acts as the dielectric of said capacitor; lowering the flying height; reading an alternating electric current signal between said magnetic read/write head and said magnetic storage medium wherein said alternating electric current signal is not due to an external power source, but is generated due to slider modulation or mechanically induced spacing change with time; measuring the alternating electric current signal between the magnetic read/write head and the magnetic storage medium; and determining modulation by the magnetic read/write head based on the alternating electric current signal wherein said alternating electric current signal is directly related to a change in capacitance of said capacitor over time wherein said change in capacitance over time is directly related to said modulation.