|
Time needed for detection and identification of bacteria can be much shortened using the unique light-scattering pattern
after being exposed to the laser source from the new platform named BARDOT (Bacteria Rapid Detection using Optical
scattering Technology). The resulting pattern is compared to the compiled pattern library to search for similarity, hence
determine the types of bacteria. The system consists of a laser source, an imaging camera, a scattering camera, and a
two-dimensional stage. First the imaging camera captures the image of the sample on Petri-dish and locates the center
coordinate locations of each cluster. Then the two-dimensional stage translates the Petri-dish such that the incident laser
beam is upon the individual sample cluster and performs a centering process which is an fine-adjustment to capture a
concentric scattering pattern. The displacement of the platform during this process is determined from the difference of
the centroid of the laser beam without sample and that of scattered laser beam with sample. Using MATLAB to design
and test the centering algorithm, the time taken for the centering algorithm can be minimized by generating a linear
relationship between the lateral distance of the sample movement and the difference of the centroid. The initial
algorithm utilized the non-linear relationship without any compensation of the difference of the centroid value. Thus it
took multiple steps of motions to reach the center location if the difference of colony center to the laser center is larger
than the radius of the sample cluster. With the help of newly designed algorithm, a linear relationship is achieved via
identifying the specific location of the starting point of centering algorithm and compensating the corresponding centroid
difference to match the actual displacement. Therefore the total time needed to satisfy the centeredness of the scattering
pattern is minimized.
|
