Abstract: A sensor device (1-5) has a sensing surface on which, in use, first molecules (5) are immobilized. The first molecules (5) are capable of interaction with second molecules which may be present in a sample of fluid applied to the sensing surface, such interaction resulting in a measurable change of some physical property of the sensor device. The sensing surface is coated with a layer (4) of diamond-like carbon to protect and preserve the integrity of the sensing surface.

Abstract: A method for monitoring the interaction of molecular species utilizes a sensor device comprising a substrate (1) with a waveguide (2) formed on the surface thereof. A grating (3) is formed in one of the surfaces of the waveguide (2). A beam of light (6) is incident on the grating (3) and the angle of incidence at which maximum reflection occurs is monitored. A first molecular species is immobilized on the waveguide (2). Changes in the angular position of the reflection maximum provide an indication of interaction of the first molecular species with a second molecular species contained in a sample brought into contact with the sensor device.