Multi-grating biosensor for label-independent optical readers

A method of measuring a signal resonant wavelength of a resonant waveguide (RWG) biosensor, comprising:

• operably disposing in a well of a microplate the RWG bio sensor having spatially separated signal grating and reference-grating regions with a non-resonance region in between, wherein the reference-grating region has a same grating structure as the signal-grating region but is deactivated so that no chemical binding can occur, and wherein the signal-grating region does not overlap the reference-grating region;
• irradiating the signal-grating region with an incident optical beam to generate reflected signal light without touching the reference-grating region, thereby generating reflected signal light and no reflected reference light;
• and
• spectrally analyzing the reflected signal light to obtain the signal resonant wavelength.

A method of measuring a signal resonant wavelength of a resonant waveguide (RWG) biosensor using an optical reader having a spatial resolution limit, comprising:

• operably disposing in a well of a microplate the RWG biosensor having spatially separated signal-grating and reference-grating regions with a non-resonance region in between wherein the reference-grating region has a same grating structure as the signal-grating region but that is deactivated so that no chemical binding can occur, and wherein the signal-grating region does not overlap the reference-grating region;
• using an optical reader system having a resolution limit, simultaneously irradiating the signal-grating region, the reference-grating region and the non-resonance region with incident light to generate reflected light, wherein the non-resonance region has a minimum width greater than the spatial resolution limit;
• establishing from the reflected light, a reflected signal component from the signal-grating region, a dark component from the non-resonance region, and a reflected reference component from the reference grating region;
• and
• spectrally analyzing the reflected signal component to obtain the signal resonant wavelength.