Patent ID: 8378669

Claim:
An integrated magnetic particle measurement device for detecting a presence or absence of magnetic particles in a sample volume, comprising: a substrate having a surface; at least one sensor cell, said at least one sensor cell comprising a differential sensor pair including an active sensor oscillator configured to have an active sensor oscillator frequency, said active sensor oscillator frequency responsive to one or more magnetic particles situated within a sample volume and a reference oscillator configured to have a reference sensor oscillator frequency said at least one sensor cell configured to be operative in the absence of an externally applied magnetic field; a selector circuit coupled to said active sensor oscillator and to said reference oscillator and configured to provide a selected one of said active sensor oscillator frequency and said reference sensor oscillator frequency at a selector circuit output terminal; and a frequency measurement circuit having a frequency measurement output terminal, said frequency measurement circuit communicatively coupled to said selector circuit output terminal said frequency measurement circuit configured to provide as a time-multiplexed output at said frequency measurement output terminal a selected one of a first count representative of said active sensor oscillator frequency and a second count representative of said reference sensor oscillator frequency, a calculated difference between said first count and said second count indicative of a presence or an absence of one or more magnetic particles within said sample volume of said active sensor oscillator of said at least one sensor cell.