Abstract text

A test device includes one or more sample wells and a biosensor placed in the well. The biosensor includes structural features promoting confinement of a deposited material, e.g., surface chemistry material, to stay within a specified predetermined area in the well. The biosensor is also constructed with two or more distinct spatial regions exhibiting different resonance values (“peak wavelength values” or PWV). One of the distinct spatial regions encompasses the specified predetermined area where the material is deposited and exhibits resonance at PWV1. A distinct spatial region surrounding the specified predetermined area exhibits resonance at PWV2. A buffer zone may be provided between the two areas. The device enables detection of lower analyte concentrations and improves intra-well self-referencing capability for the biosensor.