Patent ID: 7427745

Claim:
A device comprising: an interface between a transparent body and a capillary space, at least one fluid reservoir, an amount of fluid, one or more fluid displacement elements to displace the amount of fluid between said fluid reservoir and said capillary space in order to change an operating state of the device from a first operating state to a second operating state, and in order to change the operating state of said device from said second operating state back to said first operating state, said first operating state allowing total internal reflection of oblique light rays impinging on an active area of said interface and said second operating state allowing transmission of said oblique light rays through said active area of said interface, one or more fluid ducts opposite said active area for delivering the amount of fluid to said capillary space, one or more further ducts for transferring a second fluid from said capillary space when the operating state is changed from the first operating state to the second operating state, and an absorber configured to absorb the light rays transmitted through said active area of said interface.