A Microfluidic Pervaporation Device for Fabrication of Nanoparticle-Based Metalens for Dry Environment Super-Resolution Imaging

Project: Research

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Traditional electron-based microscopy has played an irreplaceable role in “imaging” nanoscale entities. However, the radiation dose that the specimens are exposed to by the system’s energetic electron beam is comparable to the irradiation from the explosion of a 10-megaton hydrogen bomb approximately 30 meters away, making this technology unsuitable for non-destructive observations such as integrated circuit device imaging or biological analysis. On the other hand, conventional optical microscopes have certain unique advantages, such as the ability for noninvasive, real-time, large-area, and fluorescent or white-light imaging. Nevertheless, the optical resolution for optical microscopes is limited by Abbe’s diffraction limit, and by the fact that highspatial frequency information from a sample’s surface carried by evanescent waves are lost in the far-field.   Our team will develop a novel process to create nanoparticle-based metalenses (NPMs) for super-resolution imaging using a microfluidic pervaporation device. Currently, no technology exists to reliably and accurately fabricate hemispherical metalenses with controllable morphology. We will demonstrate a three-dimensional microfluidic device where nanoparticle colloidal solutions can be delivered into it and are then converted into NPMs via a pervaporation process. These NPMs will have two major advantages over exiting microsphere-based superlenses: a) improvement of collection efficiency of the evanescent waves from sample surfaces by increasing the imaging ‘spot’ from point-contact to surface-contact; b) elimination of the requirement that the refractive index ratio between microsphere and its immersion medium should be less than two, which has confined the magnification factor and resolution of microsphere-based super-resolution imaging. There are several critical engineering challenges and scientific issues that will be addressed in order to realize super-resolution metalenses with controllable hemispherical morphology. We will 1) create “lens chamber” molds using glycerol micro-droplets with morphologies that depend on factors such as liquid surface tension and substrate surface’s hydrophobicity; 2) explore the pervaporation phenomenon in a microfluidic device in order to efficiently and repeatably transform nanoparticle colloidal solutions into solid metalenses; 3) perform numerical analysis to further elucidate the mechanisms behind the propagation of surface evanescent waves by tightlypacked nanoparticles in a metalens.   The success of this project will significantly impact the research area of visible-light superresolution imaging by improving both the image-resolution and field-of-view of superlenses operating in dry environments. These results will potentially benefit Hong Kong and the global communities greatly by providing a novel solution for applications in fields such as integrated circuit inspection and failure analysis, optically-based nanolithography,and ultrasensitive photon detection. 


Project number9042994
Grant typeGRF
Effective start/end date1/01/21 → …