Analyte sensing in a fluid medium

A method for fabricating a sensor for sensing an analyte in a fluid medium, the method comprising:

• providing a wafer comprising a substrate, a dielectric layer on the substrate, and a semiconductor adlayer on the dielectric layer;
• enacting microlithographic processing of the semiconductor adlayer to define:
• a curved and elongate semiconductor waveguide confined to the dielectric layer,
• an in-coupling window arranged at a first end of the waveguide and configured to couple optically to an optical source, and
• an out-coupling window arranged at a second end of the waveguide and configured to couple optically to an optical detector;
• and
• selectively etching the dielectric layer to define:
• a first dielectric region that supports and encloses the first end of the waveguide;
• a second dielectric region that supports and encloses the second end of the waveguide;
• and
• a third dielectric region that supports but does not enclose a middle segment of the waveguide, to suspend the middle segment of the waveguide.

A sensor for sensing an analyte in a fluid medium, the sensor comprising:

• a curved and elongate semiconductor waveguide;
• an in-coupling window arranged at a first end of the waveguide and configured to couple optically to an optical source;
• an out-coupling window arranged at a second end of the waveguide and configured to couple optically to an optical detector;
• and
• a dielectric layer including:
• a sensory region that supports but does not enclose a middle segment of the waveguide,
• a groove, wider than the waveguide, formed along a path of the middle segment of the waveguide over the sensory region, and
• at least one ridge arranged in the groove, each ridge extending across the groove, adherently supporting the middle segment of the waveguide.