Abstract: In Magnetic Resonance Imaging (MRI) guided intervention procedures, the flexibility and reliability of the mammary gland fixation device are important indicators for ensuring the quality of surgery. This paper presents a bionic flexible fixation system for MRI-guided breast biopsy, and establishes a mathematical model of the palm-type curved plate and a breast compression model. The bending angle, eccentricity, and tightening stroke of the palm-type curved plate are considered the main influencing factors. The bending angle and eccentricity of the bionic palm-type curved plate and flexible fingers are optimized, and a prototype of the breast fixation system is developed. The experimental results show that when the external force is 10 N, the average repetitive accuracy of four lesion points is 
0.71 mm, 0.60 mm, 0.63 mm, and 0.68 mm, respectively. When the pressures are 8 N, 10 N, and 12 N, the thickness of the compressed tissue is 76.27 mm, 72.8 mm and 68.73 mm, respectively. It has good repetitive accuracy and is compatible with the concept of flexible fixation that reduces the uncomfortable feeling of the human body. We propose that by optimizing the flexible tightening mechanism, it is feasible to properly control the external compression force to effectively reduce the compression pain for patients while guaranteeing the tightening reliability in breast biopsy.

Key words: breast biopsy, bionic palm, flexible fixation, optimized design, MRI robotics