Ansuman Banerjee

University of Cincinnati, Cincinnati, OH, United States

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Publications (6)10.17 Total impact

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    ABSTRACT: Fluorescence detection is one of the most widely used techniques for measuring analyte concentration in biological applications. Although used frequently with bulk systems, there are important considerations in using this approach in thin (<100 μm) microfluidic lab-on-a-chip (LOC) systems in relating the measured fluorescence signal to analyte concentration. In this work, a general relationship between the photoresponse of an on-chip organic photodetector (OPD) and concentration of a fluorescent dye Rhodamine 6G in a microfluidic chip is presented. The developed theoretical model for photoresponse matches well to the extreme sub-linearity observed in measurements in a dilution series from 10 nM to 1 mM. The influence of the system factors, such as noise, detector sensitivity, and optical power were also analyzed to indicate design changes to improve the system performance and limits of detection even further.
    Journal of Luminescence 06/2010; 130(6-130):1095-1100. DOI:10.1016/j.jlumin.2010.02.002 · 2.37 Impact Factor
  • Yun Shuai, Ansuman Banerjee, David Klotzkin, Ian Papautsky
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    ABSTRACT: In this paper, we present a high-sensitivity approach for on-chip fluorescence-based measurements for disposable lab-on-a-chip (LOC) with an integrated organic light-emitting diode (OLED) excitation source and organic photodiode (OPD) detector. A simple and inexpensive cross- polarization scheme was used to filter out excitation light from the fluorescent dye emission spectrum. We incorporated a bi- layer OPD detector with responsivity 10 times higher than conventional single heterojunction OPD, resulting in a detection limit of 1 nM, which is a 1,000-fold improvement over previous publications. The dynamic experiment was conducted and the result shows promising application in realtime fluorescence analysis. The demonstrated on-chip fluorescence detection approach is ideally suited for integration with disposable LOC devices for point-of-care diagnostics and on-site environmental testing.
    University/Government/Industry Micro/Nano Symposium, 2008. UGIM 2008. 17th Biennial; 08/2008
  • Ansuman Banerjee, Yun Shuai, David Klotzkin, Ian Papautsky
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    ABSTRACT: This paper discusses the concentration to detected photocurrent relationship of a high-sensitivity MEMS based on-chip fluorescence detection system consisting of a light source, sample chamber, and detector all integrated into a set of 3"xl" glass slides. A green organic light-emitting diode (OLED) has been used as the excitation source and organic photodiode (OPD) has been used as the fluorescence detector. A novel integrated cross-polarization scheme was used to filter out excitation light from the fluorescent dye emission spectrum. Two commonly used dyes in biotechnology applications, Rhodamine 6G and Fluorescein, have been detected down to ten's of nanomole which is several order of magnitude improvement in detection limits over existing literature using OPD. A theoretical model has been developed to study fluorescence signal variation with dye concentration for this particular system. A theoretical curve fitting has been performed based on the model. The theoretical fit matches closely with experimental data. Future modifications of the detection system have been suggested based upon results obtained from modeling.
    University/Government/Industry Micro/Nano Symposium, 2008. UGIM 2008. 17th Biennial; 08/2008
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    ABSTRACT: The trend in medical equipment is toward compact and integrated low-cost medical test devices. Fluorescence-based assays are used to identify specific pathogens through the presence of dyes, but typically require specialized microscopes and narrowband optical filters to extract information. We present a novel, high-sensitivity, cost-effective, cross-polarization scheme to filter out excitation light from a fluorescent dye emission spectrum. This concept is demonstrated using an inverted microscope fitted with a halide lamp as the excitation source and an organic photo voltaic (organic photodiode) cell as the intensity detector. The excitation light is linearly polarized and used to illuminate a microfluidic device containing a 1 volume of dye dissolved in ethanol. The detector is shielded by a second polarizer, oriented orthogonally to the excitation light, thus reducing the magnitude of the detector photocurrent by about 25 dB. The signal due to fluorescence emission light, which is randomly polarized, is only attenuated by about 3 dB. As proof-of-principle, the fluorescence signal from the dyes Rhodamine 6G (emission wavelength of 570 nm) and Fluorescein (emission wavelength 514 nm) are measured in a dilution series with resulting emission signal being detected by an organic photodiode. Both dyes were detectable down to concentrations of 10 nM. This suggests that an integrated microfluidic device, with an organic photodiode and an organic light emitting excitation source and integrated polarizers, could be fabricated to realize compact and economical lab-on-a-chip devices for point-of-care diagnostics and on-site analysis.
    IEEE Sensors Journal 06/2008; 8(5-8):621 - 627. DOI:10.1109/JSEN.2008.918961 · 1.85 Impact Factor
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    ABSTRACT: We report a high-sensitivity, disposable lab-on-a-chip with a thin-film organic light-emitting diode (OLED) excitation source and an organic photodiode (OPD) detector for on-chip fluorescence analysis. A NPB/Alq3 thin-film green OLED with an active area of 0.1 cm(2) was used as the excitation source, while a CuPC/C(60) thin-film OPD with 0.6 cm(2) active area was used as a photodetector. A novel cost-effective, cross-polarization scheme was used to filter out excitation light from a fluorescent dye emission spectrum. The excitation light from the OLED was linearly polarized and used to illuminate a microfluidic device containing a 1 microL volume of dye dissolved in ethanol. The detector was shielded by a second polarizer, oriented orthogonally to the excitation light, thus reducing the photocurrent due to excitation light leakage on the detector by approximately 25 dB. The fluorescence emission light, which is randomly polarized, is only attenuated by approximately 3 dB. Fluorescence signals from Rhodamine 6G (peak emission wavelength of 570 nm) and fluorescein (peak emission wavelength of 494 nm) dyes were measured in a dilution series in the microfluidic device with emission signals detected by the OPD. A limit-of-detection of 100 nM was demonstrated for Rhodamine 6G, and 10 microM for fluorescein. This suggests that an integrated microfluidic device, with an organic photodiode and LED excitation source and integrated polarizers, can be fabricated to realize a compact and economical lab-on-a-chip for point-of-care fluorescence assays.
    Lab on a Chip 06/2008; 8(5):794-800. DOI:10.1039/b715143h · 5.75 Impact Factor
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    ABSTRACT: The trend in medical equipment is toward compact and integrated low cost medical test devices. Fluorescence-based assays are used to identify specific pathogens through the presence of dyes, but typically require specialized microscopes and narrow-band optical filters to extract information. We present a novel method of using polarizers in cross orientation with each other to filter out excitation light and allow detection of low signal levels of fluorescence with a simple intensity-based detector in the presence of high levels of excitation light. This concept is demonstrated using an inverted microscope fitted with a halogen lamp as the excitation source and an organic photovoltaic (PV) cell as the intensity detector. The excitation light is linearly polarized and used to illuminate a microfluidic device containing a 50µl volume of Rhodamine 6G dye dissolved in water. The detector (with a second polarizer orientated perpendicularly to the first) is placed over the microfluidic device. The resulting emission signal was detected by the organic PV cell down to a concentration of 100 nM This suggests that an integrated microfluidic device, with a PV detector and an organic light emitting excitation source and integrated polarizers, could be fabricated to realize a economical "lab on a chip" device for fluorescence assays.
    Proceedings of SPIE - The International Society for Optical Engineering 01/2007; DOI:10.1117/12.720741 · 0.20 Impact Factor