An integrated magnetic spectrometer for multiplexed biosensing

There is high demand for at-home and point-of-care medical diagnostic tools as a step toward fast, low-cost, personal medicine. Integrated biosensors based on magnetic labeling schemes offer higher sensitivity and lower cost due to the elimination of the optics and have emerged as a viable alternative to assays that use fluorescence for biomolecular detection. For instance, the frequency-shift sensor of [1] demonstrates a high-sensitivity example of a cost-effective magnetic particle biosensor in CMOS with no need for external magnets. Despite their cost and sensitivity advantages, magnetic biosensors reported so far suffer from a lack of multi-probe diagnostics similar to fluorescent-based approaches that use multiple colors for simultaneous single-site multiple target differentiation. This is primarily because current approaches measure changes in the magnetic susceptibility, χ, either at low frequencies [2,3] or at a fixed RF frequency [1]. Consequently, these approaches do not provide a clear path for differentiating between a large number of small magnetic particles vs. a smaller number of larger size particles with similar magnetic content.