| 摘要 |
<p>An apparatus for detecting the presence and/or concentration of biomolecules (41a-41c), in particular DNA, comprises a boundary surface (39) between an optically denser medium (here a glass prism 35) and an optically rarer medium (here a solvent 40). Biomolecules (41a-41c) adsorb to said boundary surface (39) and alter the characteristics of impinging light. The apparatus uses surface plasmon resonance (SPR), e.g. to excite the biomolecules (41a-41c). In order to operate the apparatus at theta = theta SPR ( theta being the angle of incidence) and thus control the energy transferred to the biomolecules (41a-41c), the excitation light reflected at the boundary surface (39) is monitored (detector 46). The angle of incidence ( theta ) is controlled (loop 49) - e.g. by rotation of a desk - such that the intensity of the reflected light is always kept at a minimum, thus ensuring that theta = theta SPR. The disclosure also relates to a method of controlling the angle of incidence theta . <IMAGE></p> |
