Photon Counting for Life Sciences

What is photon counting in life science research?

Photon counting in life science research means detecting single photons emitted by a biological sample and recording the exact arrival time of each one. Instead of measuring only how bright a signal is, researchers obtain the full distribution of photon arrival times. This reveals fluorescence lifetimes, molecular dynamics and interactions that intensity alone cannot show, and it works at the very low light levels typical of living samples.

Life science applications we support

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Fluorescence Lifetime Flow Cytometry (FLFC)

Flow cytometry is a sheath-flow-based technique that uses laser excitation and fluorescence to evaluate the physical and chemical characteristics of cells or other suspended particles in a fluid stream

Figure 1: Schematic of a fluorescence lifetime flow cytometry setup. A pulsed laser excites a fluorescent sample. Emitted photons (blue, light red, dark red) are filtered by spectrum and collected by single-photon detectors. A time-to-digital converter (Time Tagger) correlates the laser trigger with photon arrival times to measure fluorescence lifetime histograms. These fluorophore-unique histograms enable fluorophore discrimination, even in the case when spectral filters fail due to spectral overlap.

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Dynamic Light Scattering (DLS) Particle Size Analysis

Next-generation multi-angle DLS turnkey design with built-in consistency checks, raw photon access, and intelligent spike filtering for fast, reliable particle sizing.

Figure 1. The image consists of two main parts: the top half is a schematic of a Dynamic Light Scattering (DLS) setup, and the bottom half shows the DLS analysis and comparison between large and small particles based on the measured data. Top: A laser source emits a monochromatic light that travels horizontally and enters a transparent sample container (a cuvette). Inside this cuvette, several blue particles are shown in random “Brownian” motion. A Single Photon Detector “SPD” is situated at an angle θ from the laser propagation to collect the scattering data from the sample. The correlator acquires and calculates the correlation of the timing data from the detectors in real time. A cable connects the correlator to a computer “PC”, where data analysis is performed. Bottom: Visualization of the different behavior of small and large particles in solution, represented as blue circles (dark and light blue, respectively) and with their hydrodynamic radius (Rs and RL, respectively). Three different analysis plots are shown underneath, from left to right: Left: Intensity vs. Time (s): Two jagged lines represent the fluctuations in light intensity over time.The large particle has slower and smoother fluctuations in light blue color. The small particle shows faster fluctuations in dark blue color. Middle: Autocorrelation Function (ACF) vs. log 𝜏 (s): This plot shows two autocorrelation curves that represent the diffusion behavior of particles suspended in the examined solution. The large particle's curve decays more slowly. The small particle's curve decays faster, reflecting quicker diffusion. Right: Intensity vs. Size (nm): A graph with two sharp Gaussian curves. The left peak is labeled Rs for the small particle. The right peak is labeled RL for the large particle, indicating a size distribution derived from the correlation data.

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Single-Photon Counting Raman Spectroscopy

The single-photon counting Raman spectroscopy combines the principles of Raman spectroscopy with single-photon counting techniques, enabling the detection of weak Raman signals even at low analyte concentrations

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Fluorescence Lifetime Imaging (FLIM)

Discover fluorescence lifetime imaging (FLIM), a powerful imaging technique for mapping fluorescence lifetimes with picosecond precision. Learn how Swabian Instruments' Time Taggers enable high-resolution FLIM measurements using advanced timing electronics, supporting detectors like PMTs, SPADs, and SNSPDs for cutting-edge research applications

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Single Photon Microscopy

Did you ever wish you could save time by having all signals from your setup captured by one single device and made available to you by a versatile and intuitive software engine?

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Time-Resolved Photoluminescence (TRPL)

Time-resolved photoluminescence (TRPL) is a powerful technique that measures the photoluminescence decay (emission lifetime) of materials after pulsed excitation, thereby probing their optical and electronic properties. By tracking how excited states relax back to the ground state, TRPL distinguishes between radiative and non-radiative pathways, yielding lifetimes that report on charge-carrier dynamics, trap/defect activity, and other loss mechanisms.

Why is photon counting important for life science research?

Time-correlated single photon counting (TCSPC) is one of the most powerful measurement techniques in modern biophotonics. Swabian Instruments Time Taggers provide the timing precision and throughput these measurements need, recording the arrival time of every detected photon with picosecond accuracy and streaming the raw data for live or later analysis. Where an experiment needs synchronized lasers, detectors or scanners, the Pulse Streamer Series provides the precise signal generation.

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