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Compact optofluidic platform for detection of bio-molecules

 

A concept is presented for analyzing fluorescence from bio-molecules by using a compact fluidic platform that is integrated onto a chip-size spectrometer. Particles are continuously excited within a novel waveguide. Fluorescence spectra are recorded as the particles traverse the detection area. Unlike most other approaches for detecting and identifying an analyte, ours does not require immobilizing suspect particles for interrogation. Rather, it takes advantage of the general necessity to detect such particles in real time as they are moving. A continuous excitation of the analytes is required while they are moving across the detection area. Conventionally, evanescent field excitation is used to provide fluorescence excitation over an extended area. In order to improve the interaction between light and analyte we are using an anti-resonant waveguide, in which the light is guided within the target-containing medium, thereby enabling an extended interaction length. In this concept a low-refractive-index fluid is sandwiched between two transparent glass slides with higher refractive index. Depending on the coupling angle light is either guided purely in the glass slides or is coupled into anti-resonant waveguide modes. These anti-resonant waveguide modes are inherently lossless and can have very high confinement factors within the liquid. Compact spectrometers are integrated along a fluidic channel. The spectrometers are composed of a detector array which is coated with a linear variable band-pass filter. The filter converts the spectral fluorescence information into a spatially dependent signal which is analyzed by the detector array. The photosensitive area of this spectrometer can be as large as the size of the detector array. This area is large compared to conventional spectrometers where the light has to be focused onto a small slit in order to receive good wavelengths separation. Therefore, the chip-size spectrometer is especially favorable for large light emitting areas or moving particles.

 
citation

Schmidt, O. ; Bassler, M. ; Kiesel, P. ; Johnson, N. M. Compact optofluidic platform for detection of bio-molecules. Optics East 2006, Session LS303: Lab-on-a-Chip: Platforms, Devices, and Applications II; 2006 October 1-4; Boston; MA; USA.