Evanescent wave device, and method of operation

The invention relates to a device (10) comprising a support (14) having a waveguide (42) for propagating light at at least one wavelength generating outwardly evanescent waves. According to the invention the device comprises means for receiving a liquid sample configured to receive the liquid sample in contact with the waveguide (42) so as to impregnate the waveguide with a portion of the sample liquid and means operable to withdraw from contact with the liquid sample with the waveguide (42).