Performance Analysis of Non-Interferometry Based Surface Plasmon Resonance Microscopes

Recent advances in surface plasmon resonance imaging and biological applications

Surface Plasmon Resonance Imaging (SPRI) is a robust technique for visualizing refractive index changes, which enables researchers to observe interactions between nanoscale objects in an imaging manner. In the past period, scholars have been attracted by the Prism-Coupled and Non-prism Coupled configurations of SPRI and have published numerous experimental results. This review describes the principle of SPRI and discusses recent developments in Prism-Coupled and Non-prism Coupled SPRI techniques in detail, respectively. And then, major advances in biological applications of SPRI are reviewed, including four sub-fields (cells, viruses, bacteria, exosomes, and biomolecules). The purpose is to briefly summarize the recent advances of SPRI and provide an outlook on the development of SPRI in various fields.

Boosting Low-Temperature Resistance of Energy Storage Devices by Photothermal Conversion Effects

While flexible supercapacitors with high capacitance and energy density is highly desired for outdoor wearable electronics, their application under low-temperature environments, like other energy storage devices, remains an urgent challenge. Solar thermal energy converts solar light into heat and has been extensively applied for solar desalination and power generation. In the present work, to address the failure problem of energy storage devices in a cold environment, solar thermal energy was used to improve flexible supercapacitor performance at low temperature. As a proof of concept presented here, a typical all-solid-state supercapacitor composed of activated carbon electrodes and gel polymer electrolyte was coated by a carbonized melamine sponge. Due to the ability of photothermal conversion of carbonized melamine sponge, the capacitance of the supercapacitor was greatly enhanced, which could be further improved by adding surface plasmonic nanomaterials, for example, Ag nanowires. Compared with the device without photothermal conversion layers, the specific capacitance increased 3.48 times at -20 °C and retained 87% capacitance at room temperature and the specific capacitance increased 6.69 times at -50 °C and retained 73% capacitance at room temperature. The present work may provide new insights on the application of solar energy and the design of energy storage devices with excellent low-temperature resistance.

Analysis of the surface plasmon resonance interferometric imaging performance of scanning confocal surface plasmon microscopy

Here, we apply rigorous coupled-wave theory to analyze the optical phase imaging performance of scanning confocal surface plasmon microscope. The scanning confocal surface plasmon resonance microscope is an embedded interferometric microscope interfering between two integrated optical beams. One beam is provided by the central part around the normal incident angle of the back focal plane, and the other beam is the incident angles beyond the critical angle, exciting the surface plasmon. Furthermore, the two beams can form an interference signal inside a confocal pinhole in the image plane, which provides a well-defined path for the surface plasmon propagation. The scanning confocal surface plasmon resonance microscope operates by scanning the sample along the optical axis z, so-called V(z). The study investigates two imaging modes: non-quantitative imaging and quantitative imaging modes. We also propose a theoretical framework to analyze the scanning confocal surface plasmon resonance microscope compared to non-interferometric surface plasmon microscopes and quantify quantitative performance parameters including spatial resolution and optical contrast for non-quantitative imaging; sensitivity and crosstalk for quantitative imaging. The scanning confocal SPR microscope can provide a higher spatial resolution, better sensitivity, and lower crosstalk measurement. The confocal SPR microscope configuration is a strong candidate for high throughput measurements since it requires a smaller sensing channel than the other SPR microscopes.