Tagungsbeiträge

We describe a new transport mechanism that supports the localized collection of airborn analytes at higher rates when compared to diffusion based standard commonly used. It combines advanced aerosol science with novel nanosensor designs. Background: The detection of single molecular binding events has been a recent trend in sensor research introducing various sensor designs where the active sensing elements are nanoscopic in size. While it is possible to detect single binding events, the research has not yet addressed the question of how to effectively transport airborne analytes to these point-like sensing structures. Currently, diffusion-only-transport is used and it becomes increasingly unlikely for an analyte molecule to “find” and interact with sensing structures where the active area is shrunk in size, trading an increased sensitivity with a long response time. Approach: Instead of using diffusion-only-transport, this report introduces various analyte charging methods and electrodynamic nanolens based analyte concentration concepts to transport airborne analytes to nanoscopic sensing points to improve the response time of existing gas sensor designs. We demonstrate localized collection of analytes over a wide range of molecular weights ranging from 3×1017 to 1×102 Daltons, including (i) microscopic analyte particles, (ii) inorganic nanoparticles, all the way down to (iii) small organic molecules. We also demonstrate first experimental results towards an programmable active matrix based analyte collection approach referred to as "Airborn Analyte Memory Chip/Recorder" for "OFFSITE" analyte analysis, which (i) takes samples of the particles or molecules in an Aerosol at specific points in time, (ii) transports the analyte sample to a designated spot on a surface, (iii) concentrates the analyte at this spot to achieve an amplification, (iv) repeats this sequence until the recording matrix is full, and (v) reads out the analyte matrix on the chip. Implications: In all cases we find that the collection rate is several orders of magnitudes higher than in the case where the discovered collection schemes is turned off and where collection is driven by diffusion-only-transport. The collection scheme is integrated on an existing surface-enhanced Raman spectroscopy based sensor. In terms of response time, the process is able to detect analytes at 9 parts per million within 1 second. As a comparison, 1 hour is required to reach the same signal level when diffusion-only-transport is used. The novel "Airborn Analyte Memory Chip/Recorder" achieved by this approach could be a commodity item that is placed in an environment that a user would like to keep a record from. The information is retrieved on an as needed basis. Offsite analysis of the chip storing the information would make this approach more economical than an online monitoring system for all kinds of threads.

We present an anamorphotic imaging system with a separately tunable magnification in horizontal and vertical direction in order to change the aspect ratio of the image. The design is based on cylindrical membrane lenses made of aluminum nitride with tunable focal power to realize a vario system without moving elements. We demonstrate the design concept of cylindrical lenses with a very compact geometry, the optical system as well as experimental results.