Optical systems are the eyes of biophysics and medical research. Thanks to the development of optical tweezers technology, we can manipulate the movement of particles using light, greatly expanding the application scope of optical systems. In this thesis, we primarily utilized optical systems to address several issues in biophysics and medicine. To begin with, we introduced a real-time multi-particle tracking system based on bright-field illumination. This system reduces background noise caused by laser interference and achieved lowers costs, thereby expanding the applicability of particle and cell tracking. Building on this foundation, I combined optical tweezers with microfluidic chips to develop a rapid device for measuring the dielectrophoretic force of particles and cells. Experimental results matched theoretical predictions, validating the device's reliability and enhancing researchers' methods for characterizing the dielectrophoretic forces of small particles and cells. Subsequently, we developed a rapid blood purification and screening device using optical tweezers, achieving a screening accuracy of up to 98.3%. The feasibility of this device was verified through in vitro bacterial culture experiments. This technology holds significant potential for early detection and treatment of sepsis in medical applications. These optical tweezer-based efforts expand the cross-disciplinary applications of optical systems in biophysics and medicine.