Low-cost high performance readout system for fiber-optic biosensors

Abstract

We have developed an instrument for real time continuous interferometric measurement of dimensional change in stimuli-responsive hydrogel sensors. The instrument consists of a superfluorecent LED and a low-cost grating spectrometer. All signal conditioning and processing is performed using a microprocessor. We have tested the instrument with a glucose sensitive hydrogel sensor. The rms noise on the length measurement is less than 1.4 nm, whereas rms noise on the length change is less than 0.25 nm. An observed bias of the length measurement can be reduced by minor changes in the frequency estimation algorithm used.