Abstract: A microfluidic chip and compatible bio-sensor are provided to detect and/or quantify an analyte in a sample fluid, and preferably to simultaneously quantify multiple analyte(s) in a sample fluid volume. A fluid volume containing microbeads is flowed through an elongate planar sample chamber of the microfluidic chip. Microbead traps or barriers in the sample chamber retain the microbeads. The sample fluid volume is Excitation flowed through the sample chamber. A conjugate specific to the analyte is and labeled with a fluorophore is introduced into the sample chamber. In the biosensor, an excitation wavelength is directed parallel to the plane of the sample chamber. Any fluorescent emissions from the sample chamber are detected in a direction substantially orthogonal to the plane of the sample chamber by a photodetector, and correlated to an amount or concentration length of sample chamber of analyte in the sample fluid volume.

Abstract: The invention is directed to a method for detecting analytes, particularly vitamins, using a lateral flow immunoassay. The method may be used to detect vitamin D, particularly 25-hydroxy vitamin D3 or 1,25-dihydroxy vitamin D3. The method involves obtaining a fluid sample from a subject; applying the sample to a lateral flow test strip comprising a conjugate pad capable of releasing a labelled antibody against vitamin D, and a detection membrane comprising a first capture reagent specific to the antibody and immobilized on a test band; and detecting the presence or absence of vitamin D in the sample. The presence of a detectable signal in the test band is indicative of vitamin D deficiency.