Yuchao Li

By Zhiyong Gong and Yuchao Li

Three-dimensional optical manipulation of microparticles, cells, and biomolecules in a noncontact and noninvasive manner is crucial for biophotonic, nanophotonic, and biomedical fields. Optical tweezers, as a standard optical manipulation technique, have some limitations in precise manipulation of micro-objects in microfluidics and in vivo because of their bulky lens system and limited penetration depth. Moreover, when applied for trapping nanoscale objects, especially with sizes smaller than 100 nm, the strength of optical tweezers becomes significantly weak due to the diffraction limit of light. The emerging near-field methods, such as plasmon tweezers and photonic crystal resonators, have enabled surpassing of the diffraction limit. However, these methods msay lead to local heating effects that will damage the biological specimens and reduce the trapping stability. Furthermore, the available near-field techniques rely on complex nanostructures fixed on substrates, which are usually used for 2D manipulation. The optical tweezers are of great potential for the applications including nanostructure assembly, cancer cell sorting, targeted drug delivery, single-molecule studies, and biosensing.

Part of the book: Emerging Micro

By Jiahao Yan and Yuchao Li

The ability to dynamically modulate plasmon resonances or Mie resonances is crucial for practical application. Electrical tuning as one of the most efficiently active tuning methods has high switching speed and large modulation depth. Silicon as a typical high refractive index dielectric material can generate strong Mie resonances, which have shown comparable performances with plasmonic nanostructures in spectral tailoring and phase modulation. However, it is still unclear whether the optical response of single silicon nanoantenna can be electrically controlled effectively. In this chapter, we introduce two types of optoelectronic devices based on Mie resonances in silicon nanoantennas. First, we observe obvious blueshift and intensity attenuation of the plasmon-dielectric hybrid resonant peaks when applying bias voltages. Second, photoluminescence (PL) enhancement and modulation are achieved together in the WS2-Mie resonator hybrid system.

Part of the book: Applications of Nanobiotechnology

By Yuchao Li, Heng Li, Xixi Chen, Tianli Wu and Baojun Li

In recent years, with the rapid development of micro/nano optics, biophotonics, and biomedicine, micro/nano optical devices have been widely used in biosensing, medical imaging, molecular diagnosis, and other fields due to their advantages of miniaturization and integration. However, micro/nano optical devices composed of semiconductor and precious metal materials are prone to irreversible physical damage to biological cells and tissues and require chemical synthesis, which cannot be naturally degraded in vivo. In addition, due to the limitation of solid materials, micro/nano optical devices are difficult to deform and move in practical applications such as optical imaging and signal detection. Therefore, it is necessary to find a natural, biocompatible, biodegradable, and controllable micro/nano optical device. During the evolution of nature, some organisms have formed bio-optical devices that can manipulate light beams. For example, algal cells have the ability to concentrate light, which can improve the efficiency of photosynthesis. Visual nerve cells have the ability to direct light and transmit images to the retina with low loss and distortion. These natural materials capable of light regulation bring new opportunities for biological micro/nano optical devices, which have potential applications in the assembly of biological cells, detection of biological signals, imaging in vivo, and single-cell diagnosis.

Part of the book: Advances in Nanofiber Research - Properties and Uses [Working title]