Injection-spray Based Fabrication of Superlens for Applications in Super-resolution Microscopy


Student thesis: Doctoral Thesis

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Award date23 Jan 2019


Invented about 400 years ago, the optical microscope is one of the most fundamental and useful tools in scientific research as well as in modern industries. However, for most of the past four centuries, its resolution has been governed by the diffraction limit of approximately 200–250 nm in the visible spectrum. Currently, a variety of optically-based techniques exist to see beyond subdiffraction resolutions, such as the near-field scanning optical microscopy and molecular fluorescence microscopy. But these techniques have some very undesirable features, i.e., the former has limited throughput in acquisition, and the latter requires specific fluorescent molecules and laser beam excitation. On the other hand, the past decade has seen a flurry of developments for optical nanoscopes using microsphere or metamaterial superlenses, which have provided a label-free solution for direct biological observation.

This dissertation explores three types of superlenses, namely, microsphere-based, liquid-based, and nanoparticle-based, that can be applied for super-resolution microscopy applications. Firstly, commercially available microspheres were implemented with a microprobe and a scanning microscope platform that can produce large area super-resolved optical images. However, the lack of precision in controlling the distance between the sphere and the object surface has reduced the resolution enhancement of the microsphere superlens. Second, the fabrication processes of liquid-based superlens have been investigated. The effects of surface tension play an important role in the liquid-lens formation on different sample surfaces. Using the sophisticated ink-jet printing technique, in situ printing of glycerol superlenses was demonstrated for direct observation of a central processing unit (CPU) integrated-circuit (IC) chip and butterfly wing samples. As compared to microsphere superlens, the printed glycerol superlens can produce a larger field of view with similar lens sizes and also with even better image quality. Finally, a nanoparticle-based metalens was fabricated taking advantage of the nano-solid-fluid assembly technique. Subdiffraction features on an IC chip have also been resolved via this titanium oxide nanoparticle-based metalens formed on the sample surface.