Georgiy Gudkov

Single Photon Counting Module Based on Large Area APD and Novel Logic Circuit for Quench and Reset Pulse Generation

We present the design, implementation, and characterization of a single-photon counting module (SPCM) based on large-area avalanche photodiode (APD) and new logic circuit based on TTL integrated circuits (ICs) for generating precise quench and reset delays. Low dark count rate, high linearity of 2 MHz, maximum dynamic range of 12 MHz, and minimum dead time of 35 ns have been achieved with 0.2 mm peltier-cooled single photon avalanche diode (SPAD) [model C30902S-DTC, Perkin Elmer Optoelectronics (PKI)]. The developed module was fiberized and tested for the detection of fluorescently labeled DNA sequences. Detection sensitivity at the level of single fluorescent molecule has been demonstrated.

Silicon photomultiplier: Detector for highly sensitive detection of fluorescence signals

We demonstrate use of silicon photomultipliers (SiPMs) in single photon counting mode for detection of very weak laser induced fluorescence (LIF). Detection of LIF in DNA-sequencing has been performed with three different commercially available SiPMs.

32-channel single photon counting module for ultrasensitive detection of DNA sequences

We continue our work on the design and implementation of multi-channel single photon detection systems for highly sensitive detection of ultra-weak fluorescence signals, for high-performance, multi-lane DNA sequencing instruments. A fiberized, 32-channel single photon detection (SPD) module based on single photon avalanche diode (SPAD), model C30902S-DTC, from Perkin Elmer Optoelectronics (PKI) has been designed and implemented. Unavailability of high performance, large area SPAD arrays and our desire to design high performance photon counting systems drives us to use individual diodes. Slight modifications in our quenching circuit has doubled the linear range of our system from 1MHz to 2MHz, which is the upper limit for these devices and the maximum saturation count rate has increased to 14 MHz. The detector module comprises of a single board computer PC-104 that enables data visualization, recording, processing, and transfer. Very low dark count (300-1000 counts/s), robust, efficient, simple data collection and processing, ease of connectivity to any other application demanding similar requirements and similar performance results to the best commercially available single photon counting module (SPCM from PKI) are some of the features of this system.

Ultra sensitive sensor with enhanced dynamic range for high speed detection of multi-color fluorescence radiation.

This paper describes design of the new ultra sensitive sensor system for fluorescence detection applications. System comprises two units: optical spectra separation unit and detection unit. Optical unit of the sensor performs spatial spectra separation of signal from the laser excited fluorescence, and resulting spectra is collected in the detection part of the system. Optical part is built using diffraction grating as spectra separation element. Detection part comprises 32-channel photomultiplier tube working in single photon counting mode with our 32-channel amplifier. Using single photon detection technique and specific signal processing algorithms for collected data, the proposed system allows to achieve unique combination of characteristics--high sensitivity, high detection speed and wide linearity dynamic range comparing to existing commercial instruments. DNA sequencing experiments with new sensor as detection device, and using two types of lasers (Ar-ion and Nd-YAG) were carried out, yielding sequencing traces which have quality factor of 20 for read lengths as long as 650 base pairs.

Highly sensitive single photon detection system for multi-lane DNA sequencer

A multichannel fluorescence detection system for multi-lane DNA sequencer based on single photon counting is presented. The problem of elimination of the lane cross-talk caused by both optical and electronic cross-talk between the detection lanes is discussed. A novel method for elimination of the channel cross-talk is proposed. The calibration procedure for a DNA sequencer with lane cross-talk cancellation is described. Improvement in sensitivity of a DNA sequencer setup by introducing wide collection angle optical system is discussed.

Single photon detection module for multi-channel detection of weak fluorescence signals

Single photon counting is the most sensitive method for detection of weak signals. However, it has rarely been used in DNA sequencing applications because of its complexity. We present a fiberized 16-channel single photon detection (SPD) module based on avalanche photo diodes (APD). The diodes are cooled at -20 °C and the average dark count is 700 c/s with APD operating at 10V over-voltage. The proposed system uses active quenching based on basic NAND gates and delay integrated circuits (ICs) and is compact in size, robust, easily portable and requires only 120Vac supply for its operation. The fiberization of the diodes using standard components allows the connection of this system to any other system using fibers with FC connectors with up to 400μm core diameters. Comparative performance with superior commercially available photon counting modules has been obtained. The SPD module has been successfully used for fluorescence detection of weak signals in a DNA sequencing instrument and hence the suitability of large active area APD model for DNA sequencing has been verified experimentally.

Single photon spectrometer for high speed detection of multi-color fluorescence radiation

This paper describes design of the new sensor system for fluorescence detection applications. Based on single photon detection technique proposed system has unique combination of characteristics - high detection speed and wide linearity dynamic range.