The present invention provides a small (business card-sized) disposable mesofluidic or microfluidic plastic cartridge containing several straight microchannels potentially filled with culture media, solubilizing reagents (e.g., detergents) nitrocellulose paper strip, gel or other matrix materials and lyophilized paramagnetic microbeads or microparticles coated with antibodies, nucleic acid aptamers, oligonucleotides, or other types of proteins or other receptors for capture, concentration and ultrasenstive detection of target analytes in environmental, food, animal, or clinical body fluid samples.