Evanescent scanning of biochemical array

DETAILED DESCRIPTION OF THE INVENTION This invention provides apparatuses and methods for high-contrast scanning of (or detection of light from) a chemical (e.
g.
, a polymer) array.
Evanescent excitation is utilized to generate an optical signal that indicates the presence or absence of binding between ligands and receptors on pixels of the array.
As used herein, the term "pixel" refers to an individual member of the array.
The binding pattern so produced allows information to be determined about the presence of the ligand.
Any method for generating evanescent excitation on the array substrate may be employed.
Examples include, but are not limited to, any form of total internal reflection (TIR) and grating coupling.
Several embodiments for scanning a chemical array are described below.
The array surface comprises discrete regions or pixels on which chemical reactions have taken place.
Each pixel is probed for the presence or absence of a molecular tag in the vicinity of the surface.
When excited by an evanescent electromagnetic field, the molecular tags generate an optical signal.
The optical signal is detected and the resulting pattern of light and dark pixels may be analyzed by a device (for example, a computer) appropriate for analyzing such patterns.
Detection of Analytes on Chemical Array FIG.
1 illustrates how evanescent sensing of microscopic properties of analytes (or target substances) is done on a polymer array.
Although the application of the present invention is not limited by the method used for binding target substances to form the pixel array, conventional techniques of mounting analytes on an array on a suitable substrate and labeling with molecular tags (such as fluorophores), such as those techniques described in the aforementioned references, can be used.
Generally, in such an array, different pixels have different chemicals (such as polymeric segments) suitable for binding to different target substances (or analytes).
Thus, by detecting which of the pixels are excited, the presence of a target substance can be determined