Three-dimensional (3-D) surface imaging is a key technology for visualizing the 3-D form, texture, and spatial relationships of object surfaces. It is widely applied in fields such as cell biology, medicine, and engineering, providing critical insights into cell surface morphological changes, disease mechanisms, and engineering practices. Despite its importance, existing 3-D imaging techniques, such as optical 3-D imaging, computer vision 3-D imaging, and electromagnetic field measurement 3-D reconstruction, often suffer from significant limitations, including high equipment complexity, poor real-time performance, and high costs. Optical trap technology, particularly dual-beam optical traps, offers a promising alternative due to its non-contact nature, minimal cell damage, and high precision. This study aims to develop a dual-beam misaligned optical trap chip for cell rotation and surface 3-D imaging, addressing the limitations of traditional methods by providing a cost-effective, non-invasive, and highly efficient imaging solution. The proposed method is expected to enable researchers to study cell morphology and dynamics with unprecedented convenience.

The experimental system was based on a dual-beam misaligned optical trap chip, using two opposing laser beams to capture and rotate cells. The chip consisted of two single-channel fiber arrays with HI1060 single-mode fibers. The fibers were precisely aligned using a fiber precision coupling system, and then misaligned along the observation direction to induce cell rotation. The system included a 976 nm semiconductor laser, fiber attenuators, an LED light source, a 50× microscope objective, and a CMOS image sensor for observation. The misalignment distance was set to 7 μm, and the spacing between fiber end-faces was 150 μm. Yeast cells were used as the experimental samples due to their well-defined structure and ease of manipulation. The cells were suspended in a solution and introduced into the optical trap chip, where they were captured and rotated by the dual-beam system. The rotation of the cells was captured at 1° intervals using the CMOS image sensor. Image processing techniques, including Canny edge detection, were employed to extract the cell contours and reconstruct the 3-D surface model. The Canny edge detection algorithm identified regions with significant gradient changes, enabling the extraction of the outermost cell contours. These contours were then used to generate a point cloud image, which was further processed to reconstruct the 3-D surface of the yeast cells.

The experimental results showed that the dual-beam misaligned optical trap chip successfully captured and rotated yeast cells, with the rotation axis perpendicular to the observation direction. By capturing images at 1° intervals, the cell contours were extracted and converted into binary images. The Canny edge detection algorithm was used to identify regions with significant gradient changes, thereby extracting the outermost cell contours. These contours were then used to generate a point cloud image, which was further processed to reconstruct the 3-D surface of the yeast cells. The results demonstrated that this method could effectively achieve 3-D imaging of yeast cells, overcoming the limitations of traditional techniques such as low device integration, complex data processing, and high costs. However, the imaging precision was dependent on image quality, and the method could not fully present cell surface concavity. The experimental results were consistent with theoretical predictions, confirming the feasibility of using a dual-beam misaligned optical trap for cell rotation and 3-D imaging. Compared with traditional techniques, this method offered advantages such as low costs, minimal cell damage, and high imaging efficiency. However, further improvements were needed to address the limitations related to imaging precision and the inability to fully capture cell surface concavity.

This study proposes a method for cell rotation and surface 3-D imaging based on dual-beam misaligned optical trap chip. The chip offers advantages such as low cost, minimal cell damage, high imaging efficiency, and ease of integration. The experimental results demonstrate the successful capture and rotation of yeast cells, as well as the reconstruction of their 3-D surface contours. This method provides a reference for studying cell structure, characteristics, and functions, particularly in disease mechanisms and therapeutic interventions. This method has the potential to enable researchers to study cell morphology and dynamics more conveniently. Future work will focus on improving imaging precision and addressing the limitations related to cell surface concavity. Additionally, the method could be extended to other types of cells and biological samples, further expanding its applications in cell biology and medical research.