Methods and systems for biosensing are disclosed, based on microchannel surface plasmon resonance. A surface plasmon resonance (SPR) sensor (100) for detecting the presence of a target analyte in a fluid, comprising: a light source (105) a light transmissive substrate (112) a metal coating (114) of gold, silver or copper disposed on the substrate a test SPR element formed in the metal coating, the test SPR element comprising: at least one test microchannel (122) in the metal coating, the at least one test microchannel having at least one aperture (124) for the passage of light from the light source through the substrate, the at least one test microchannel configured to sustain a test plasmon resonance wave, wherein the test plasmon resonance wave emits a test surface plasmon emission (SPE) and a first coating (126) in the test microchannel, the first coating comprising capture molecules selected to interact with the target analyte a test detector (130) configured to detect the intensity of the light of the test channel (120) SPE in a predetermined wavelength band and a reference SPR element formed in the substrate, the reference SPR element comprising: at least one reference microchannel (142) in the metal coating, the at least one reference microchannel having at least one aperture (144) for the passage of light from the light source through the substrate, the at least one reference microchannel configured to sustain a reference plasmon resonance wave, wherein the reference plasmon resonance wave emits a reference SPE, a reference detector (150) configured to detect the intensity of the light of the reference SPE in the predetermined wavelength band and a controller (160) coupled to the test detector and the reference detector. The sensor can be implanted in a human body and can communicate and be powered wirelessly with an external coil placed in proximity to the implanted sensor or with a coil in an adhesive, external patch.
