Bone collision detection method for robot assisted fracture reduction based on force curve slope

BACKGROUND AND OBJECTIVE

The application of robot technology in fracture reduction ensures the minimal invasiveness and accurate operation process. Most of the existing robot assisted fracture reduction systems don't have the function of bone collision detection, which is very important for system safety. In view of the deficiencies in the research of this field, a broken bone collision detection method based on the slope ratio of force curve was proposed in this paper, which could realize the real-time detection.

METHODS

In order to analyze the factors influencing the slope of force curve, a collision mechanical model based on three-element viscoelastic model was established. The effects of four factors on the slope ratio of the force curve were studied based on the mechanical model. The proposed collision detection model was analyzed in detail. By drawing slope ratio curves under various experimental conditions, the universality of the collision detection model was proved; by comparative simulation, the differences between the slope ratio curves before and after optimization were analyzed. The factors that affect the performance of the detection model were also analyzed.

RESULTS

The results of collision experiments show that the increase of moving speed of distal bone and soft tissue mass reduces the slope ratio, while the increase of collision angle increases the slope ratio. In the verification experiment, the minimum main peak of KR_opt curve is 14.16 and the maximum is 220.7, the maximum interference value before the peak is 6.1. When the detection threshold is 10, the model can detect the collision state of the broken bone. It is also proved that after optimization, the model can effectively filter out invalid waveforms and reduce the occurrence of false detections. When a=5 and b=40, the detection model has sufficient stability and a low detection time delay.

CONCLUSION

This research developed a broken bone collision detection method based on the slope ratio of the force curve. After optimization, the method has good adaptability under a variety of experimental conditions. The collision of broken bones can be judged by setting an appropriate detection threshold. The application of this method in the robot fracture reduction system will improve the safety of the system.

Probing DNA-DNA Interactions with a Combination of Quadruple-Trap Optical Tweezers and Microfluidics

DNA metabolism and DNA compaction in vivo involve frequent interactions of remote DNA segments, mediated by proteins. In order to gain insight into such interactions, quadruple-trap optical tweezers have been developed. This technique provides an unprecedented degree of control through the ability to independently manipulate two DNA molecules in three dimensions. In this way, discrete regions of different DNA molecules can be brought into contact with one another, with a well-defined spatial configuration. At the same time, the tension and extension of the DNA molecules can be monitored. Furthermore, combining quadruple-trap optical tweezers with microfluidics makes fast buffer exchange possible, which is important for in situ generation of the dual DNA-protein constructs needed for these kinds of experiments. In this way, processes such as protein-mediated inter-DNA bridging can be studied with unprecedented control. This chapter provides a step-by-step description of how to perform a dual DNA manipulation experiment using combined quadruple-trap optical tweezers and microfluidics.

Versatile Quadruple-Trap Optical Tweezers for Dual DNA Experiments

Optical manipulation techniques provide researchers the powerful ability to directly move, probe and interrogate molecular complexes. Quadruple optical trapping is an emerging method for optical manipulation and force spectroscopy that has found its primary use in studying dual DNA interactions, but is certainly not limited to DNA investigations. The key benefit of quadruple optical trapping is that two molecular strands can be manipulated independently and simultaneously. The molecular geometries of the strands can thus be controlled and their interactions can be quantified by force measurements. Accurate control of molecular geometry is of critical importance for the analysis of, for example, protein-mediated DNA-bridging, which plays an important role in DNA compaction. Here, we describe the design of a dedicated and robust quadruple optical trapping-instrument. This instrument can be switched straightforwardly to a high-resolution dual trap and it is integrated with microfluidics and single-molecule fluorescence microscopy, making it a highly versatile tool for correlative single-molecule analysis of a wide range of biomolecular systems.