1 May 2004 Dual closed-loop, optoelectronic, auto-oscillatory detection circuit for monitoring fluorescence lifetime-based chemical sensors and biosensors
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Abstract
We present a new detection instrument for sensor measurements based on excited-state fluorescence lifetimes. This system consists of a primary optoelectronic loop containing a resonance-type rf amplifier, a modulatable fluorescence-excitation light source, a fiber optic feedback loop (with a gap for a fluorescent sensor), and a photomultiplier tube. A secondary, phase-feedback optoelectronic circuit consists of a long-wavelength-pass optical filter, a second photomultiplier tube, a photodiode, an electronic phase detector, a dc amplifier, and an electronic phase shifter (inserted into the main loop). This phase-feedback circuit is new with respect to our previous work. Under the appropriate conditions, the main loop exhibits self-oscillations, manifesting themselves as sinusoidal rf modulation of light intensity. The phase-feedback circuit detects the modulation phase shift resulting from the finite excited-state lifetimes of a fluorophore. As the excited state lifetime changes, the phase shift from the electronic phase shifter also changes, which results in a shift in self-oscillation frequency. The detection system uses self-oscillation frequency as the detection parameter and has excellent resolution with respect to changes in excited-state lifetime (~1 ps).
© (2004) Society of Photo-Optical Instrumentation Engineers (SPIE)
Emmanuel M. Rabinovich, Emmanuel M. Rabinovich, Tengiz Sviminoshvilli, Tengiz Sviminoshvilli, Michael J. O'Brien, Michael J. O'Brien, Steven Roy Julien Brueck, Steven Roy Julien Brueck, Gabriel P. Lopez, Gabriel P. Lopez, } "Dual closed-loop, optoelectronic, auto-oscillatory detection circuit for monitoring fluorescence lifetime-based chemical sensors and biosensors," Journal of Biomedical Optics 9(3), (1 May 2004). https://doi.org/10.1117/1.1688814 . Submission:
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