Fast fitting of multi-exponential decay curves

Fluorescence correlation spectroscopy ͑FCS͒ has become an important and widely used technique for many applications in physics, chemistry, and biology. Usually, FCS is measured with sensitive light detectors working in the photon-counting Geiger mode. A common property of such detectors is afterpulsing: the generation of spurious photon detection events after a genuine photon detection. Such afterpulsing causes a significant deviation of the measured autocorrelation function from its true value on a short time scale and can seriously influence derived parameters for fast processes such as triplet-state photophysics. Here, we discuss the impact of afterpulsing on FCS in detail. A new method is developed to eliminate afterpulsing effects by using time-correlated single-photon counting for separating the true fluorescence signal from afterpulsing events.

show abstract

“…It can be shown 14,15 that the most likely values of w ͑k͒ ͑t͒ at every moment t are found by minimizing the quadratic form…”

Section: ͑10͒mentioning

confidence: 99%

Using fluorescence lifetime for discriminating detector afterpulsing in fluorescence-correlation spectroscopy

Enderlein

Gregor

2005

Review of Scientific Instruments

Self Cite

102

View full text Add to dashboard Cite

show abstract

“…The hemispherical time-resolved fluorescence from human skin is then obtained by solving the radiative transfer equation using the modified method of characteristics [24,25]. Next, the fluorescence lifetimes are recovered from these decays using Fluofit [26,27] and compared with the actual lifetimes of the fluorophores used in the simulations. Finally, the time-resolved fluorescence from skin with an implanted glucose sensor is simulated and fluorescence lifetimes recovered.…”

Section: Current State Of Knowledgementioning

confidence: 99%

“…As performed experimentally, a model decay can be fit to the numerical hemispherical fluorescence decay using the incident pulse as the IRF. The software Fluofit [26,27] programmed in Matlab was used to fit the simulated fluorescence decay to a bi-exponential model of the form,…”

Section: Retrieval Of Fluorescence Lifetimesmentioning

confidence: 99%

“…Figure 3 shows the time-resolved fluorescence of skin with this implanted sensor for these two glucose concentrations. Once again, Fluofit [26,27] was used to recover the fluorescence lifetimes from these decays. For a glucose concentration of 5mM equivalent to 90 mg/dL, the recovered lifetimes were 0.0285 ns, 5.3 ns, and 11.50 ns, and their corresponding amplitudes were 0.57, 0.20, and 0.23 respectively.…”

Section: Evaluation Of An Embedded Sensor Under the Epidermis For Biomentioning

confidence: 99%

See 1 more Smart Citation

Numerical feasibility analysis of an epidermal glucose sensor based on time-resolved fluorescence

Katika

Pilon

2006

Optical Interactions With Tissue and Cells XVII

View full text Add to dashboard Cite

This paper presents numerical simulations predicting the time-resolved reflectance and autofluorescence of human skin exposed to a pulse of collimated light at 337 nm and pulse width of 1 ns. Moreover, the feasibility of using an embedded time-resolved fluorescence sensor for monitoring glucose concentration is also studied. Skin is modeled as a multilayer medium with each layer having its own optical properties and fluorophore absorption coefficients, lifetimes and quantum yields. The intensity distributions of excitation and fluorescent light in skin are then determined by solving the transient radiative transfer equation using the modified method of characteristics. In both cases, the fluorophore lifetimes are recovered from the simulated fluorescence decays and compared with the actual lifetimes used in the simulations. It was found that the fluorescence lifetime of the fluorophore contributing the least to the fluorescence signal could not be recovered while the other lifetimes could be recovered within 2.5% of input values. Such simulations could be valuable in interpreting data from time-resolved fluorescence experiments on healthy and diseased tissue as well as in designing and testing the feasibility of various optical sensors for biomedical diagnostics.

show abstract

“…In the present study, the PL properties of conducting polymer PT films doped with PcMs such as CuPc, MgPc, FePc, Li 2 Pc, and CoPc were studied comprehensively by PL and time-correlated single photon counting (TCSPC) [28][29][30][31][32] measurements to determine the fundamental PL properties of various PT-phthalocyanine complexes prepared using different solvents. Polymer films are prepared by electrochemical polymerization.…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence characterization of polythiophene films incorporated with highly functional molecules such as metallophthalocyanine

Kobe

Ohnaka

Kato

et al. 2012

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

View full text Add to dashboard Cite

The photoluminescence (PL) of conducting polymer polythiophene (PT) films incorporated with metallophthalocyanines (PcMs) such as CuPc, MgPc, FePc, Li 2 Pc, and CoPc was studied by PL and time-correlated single photon counting (TCSPC) measurements. Polymer films were prepared by electrochemical polymerization and PcMs migrated into the polymer films by a diffusion method using acetonitrile or toluene as a solvent to dissolve the PcMs. The wavelength of PL emission peaks changed significantly depending on the solvent used in the doping process. Using acetonitrile, the observed PL emission peaks originated from the Q band, whereas they were assigned to the Soret band in the case of toluene. TCSPC measurements showed that PL emission took place through a ligand-ligand transition process when using acetonitrile because the average lifetimes were comparable and independent of the central metal ions for CoPc-, Li 2 Pc-, and MgPc-doped polymer films. Conversely, using toluene, it was found that ligand-ligand emission occurred for Li 2 Pc-, MgPc-, and FePc-doped films. To identify the cause of the drastic change in PL emission pattern, x-ray photoelectron spectroscopy measurements were obtained. A lower binding energy component appeared in the C 1s core-level spectra of acetonitrile-processed PcM-doped PT films, whereas this component shifted to higher energy and overlapped with the main peak for toluene-processed PcM-doped PT films. The lower binding energy component corresponded to photoelectrons due to the C atoms in the benzene rings of the ligand. Lower binding energy components also appeared in the N 1s core-level spectra of acetonitrile-processed PcM-doped PT films, and this component shifted to higher energy for toluene-processed PcM-doped PT films. These lower energy components were assigned to the core-level peaks due to the N atoms at the meso position bridging between pyrrole rings. This suggests that the electron charge at the N sites of the meso positions in toluene-processed films was smaller than in acetonitrile-processed ones. The changes in energy at benzene C sites and meso N sites suggest that the electronic states of the phthalocyanine in the toluene-processed films were porphyrin-like, so the Soret band became dominant in the PL emission spectrum.

show abstract

Fast fitting of multi-exponential decay curves

Cited by 153 publications

References 7 publications

Using fluorescence lifetime for discriminating detector afterpulsing in fluorescence-correlation spectroscopy

Using fluorescence lifetime for discriminating detector afterpulsing in fluorescence-correlation spectroscopy

Numerical feasibility analysis of an epidermal glucose sensor based on time-resolved fluorescence

Photoluminescence characterization of polythiophene films incorporated with highly functional molecules such as metallophthalocyanine

Contact Info

Product

Resources

About