Method and apparatus for bacterial monitoring

A system for detecting target elements in a host analyte, said system comprising:

• a substrate containing an ordered array comprising a predetermined pattern of wells formed in its surface, at least some of said wells having predetermined lateral dimensions such that said target elements can fit therein;
• a broadband illumination source configured to illuminate said surface of said substrate with broadband illumination over a range of wavelengths;
• an optical detector disposed such that it collects illumination diffracted from said substrate, and outputs a reflected spectrum signal;
• and
• a signal processing unit, adapted to analyze said reflected spectrum signal to provide a measure of the effective optical depth of said wells,
• wherein at least some of said wells have a lateral dimension at least as large as those wavelengths of said illumination source which are diffracted from said substrate and detected by said optical detector, to output said reflected spectrum signal which is analyzed by said signal processing unit, such that said system can detect said target elements.