title: CMOS direct time interval measurement of long-lived luminescence lifetimes.
abstract: We describe a Complementary Metal-Oxide Semiconductor (CMOS) Direct Time Interval Measurement (DTIM) Integrated Circuit (IC) to detect the decay (fall) time of the luminescence emission when analyte-sensitive luminophores are excited with an optical pulse. The CMOS DTIM IC includes 14 × 14 phototransistor array, transimpedance amplifier, regulated gain amplifier, fall time detector, and time-to-digital convertor. We examined the DTIM system to measure the emission lifetime of oxygen-sensitive luminophores tris(4,7-diphenyl-1, 10-phenanthroline) ruthenium(II) ([Ru(dpp)(3)](2+)) encapsulated in sol-gel derived xerogel thin-films. The DTIM system fabricated using TSMC 0.35 μm process functions to detect lifetimes from 4 μs to 14.4 μs but can be tuned to detect longer lifetimes. The system provides 8-bit digital output proportional to lifetimes and consumes 4.5 mW of power with 3.3 V DC supply. The CMOS system provides a useful platform for the development of reliable, robust, and miniaturized optical chemical sensors.
authors.affiliation: Department of Electrical and Computer Engineering, McGill University, Montreal, QC H3A2A7, Canada. yaol@ime.a-star.edu.sg
authors.forename: Lei
authors.initials: L
authors.lastname: Yao
authors.forename: Ka Yi
authors.initials: KY
authors.lastname: Yung
authors.forename: Maurice C
authors.initials: MC
authors.lastname: Cheung
authors.forename: Vamsy P
authors.initials: VP
authors.lastname: Chodavarapu
authors.forename: Frank V
authors.initials: FV
authors.lastname: Bright
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D008163:Luminescent Measurements / Q000295:instrumentation*; D015336:Molecular Probe Techniques / Q000295:instrumentation*; D015203:Reproducibility of Results; D012666:Semiconductors; D012680:Sensitivity and Specificity