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Barbecue kebab skewers typically consist of various meat choices, including chicken, lamb, pork, or seafood, and vegetables such as onion and pepper. Traditionally, manual kebab-making is a time-consuming and labor-intensive process, which is considered to be replaced by semi-auto and full-auto skewering machines. Currently, semi-auto skewering machines still require two main manual preparation processes: align the small meat and vegetable pieces into lines for skewering operations; superpose the large pieces of meat and vegetables, then do skewering and cutting operations. Fully automated skewering machines also have two different strategies. The first one is to use rotating scrappers and cups with a respective depth to ensure only one item can be loaded into each cup. All the cups are arranged into sequential cup rows and cup lines for skewering operations. However, the cups are frequently left empty because the rotating scrapper design often blocks any items falling into cups. Thus, some processing facilities still need extra labor to manually fill these empty cups. Another solution is the pick-and-place method by using robot arms and real-time image processing equipment, which cannot process irregular food pieces, such as shrimps (C-shape). In this paper, a novel fully automated handling and feeding system has been developed to prepare and connect the skewering operations to establish unattended kebab production lines. The performances of singulation, handling, and feeding operations have been investigated with different parameter settings and food items. Besides, the presented machine system is the first realization of unattended kebab production lines to process shrimps (C-shape), and the first design of using horizontal skewering operation to produce meat and vegetable kebabs (cube+ square piece) and shrimp and vegetable kebabs (C-shape+ square piece). This study will be beneficial for developing more effective next-generation skewering technologies and better value-added meat and seafood products. 

Optical tweezers can control the position and orientation of individual colloidal particles in solution. Such control is often desirable but challenging for single-particle spectroscopy and microscopy, especially at the nanoscale. Functional nanoparticles that are optically trapped and manipulated in a three-dimensional (3D) space can serve as freestanding nanoprobes, which provide unique prospects for sensing and mapping the surrounding environment of the nanoparticles and studying their interactions with biological systems. In this perspective, we will first describe the optical forces underlying the optical trapping and manipulation of microscopic particles, then review the combinations and applications of different spectroscopy and microscopy techniques with optical tweezers. Finally, we will discuss the challenges of performing spectroscopy and microscopy on single nanoparticles with optical tweezers, the possible routes to address these challenges, and the new opportunities that will arise.