Pulse-based interface circuits for SPR sensing systems [analyte concentration measurement]

This paper presents a means for reducing the impact of dark current, photodetector mismatch (fixed pattern noise), and the background medium on the signals generated by a surface plasmon resonance (SPR) sensing system for determining the concentration of targeted analytes in solution. Results for each circuit component (simulated and experimental) correlate well, with a maximum error of 3%, 7% and 12% in basic behavior (between simulated and actual results) for the dark current reduction, background medium compensation, and weighted sum circuits at relevant operating points, respectively. System level results on SPR signals also demonstrate the usefulness of these circuits for system-on-chip style signal processing. The chip produces a single output that indicates the refractive index (and resulting analyte concentration) of an SPR probe, independent of fluctuations in the background medium.