Innovative Sensor System with Microgoblets Allows Marker-free Optical Analysis
A portfolio of three patent families concerning a micro-optical element including a resonator substrate, at least one microresonator including a rotationally symmetrical body mounted on the resonator substrate, and a light-reflecting element including a ring-shaped mirror that surrounds the rotationally symmetrical body.
Biotechnology and medical technology need sensitive sensors for selective, marker-free detection of selected substances in liquids analytes. Especially detecting very low concentrations or single molecules makes huge demands on sensors. Light in microresonators is confined by optical total reflection in a space region typically of a size on the order of a few micrometers. Light waves are reflected at the surface of the resonator. They generate resonances for precisely those wavelengths whose integral multiple of wavelength corresponds to the circumference of the resonator. This path length is referred to as whispering gallery by analogy with an acoustic phenomenon. When molecules of an analyte agglomerate on the surface of the resonator, this adds to the circumference of the microresonator. This changes the resonance wavelength. In basic research, this has been used to detect single molecules. The microresonator versions known to date can be operated only under strictly controlled laboratory conditions, because the light has to be fed to the microresonators and extracted from them by means of an optical fiber of only 1 µm outside diameter. A new sensor system from the Institute of Microstructure Technology (IMT) and the Institute of Applied Physics (AP) improves the familiar approaches in several ways by offering a novel type of microresonator, so-called microgoblets. These microgoblets are manufactured in parallel procedures allowing mass fabrication. The polymers used as the resonator material allow the microgoblets to be designed very simply as lasers. As a sensor signal, this novel design detects the change in laser wavelength by feeding molecules of the analyte. The use of microresonators as lasers for the first time allows them to be operated in a free-beam arrangement. Consequently, there is no need for the usual complicated step of coupling out via an optical fiber. The entire sensor system comprises a covered fluidic chamber containing a microgoblet or an array of microgoblets. In order to detect laser emission with an optimum signal-to-noise ratio, it is fed through a ring-shaped mirror to signal evaluation. The sensor system can be mass produced.