Announcement of the Results

We have revolutionarily introduced a new type of bidirectional hinge tube based on the "interlocking puzzle" structure, achieving a perfect unity of precise single-plane deflection and high bending resistance. This design, through a unique laser-cut pattern, limits the bending motion to a single plane (up/down direction), while maintaining axial thrust and 1:1 torque transmission capability. Through biomechanical testing, the deflection angle accuracy of the new hinge tube reaches ±0.3°, the axial compression stiffness is increased by 40%, and the torsional stiffness is increased by 35%. This provides an unprecedented level of control accuracy for complex intracavitary surgeries.

Research and Development Background Challenges

The traditional hinge tube design has three major structural flaws: Firstly, there is the problem of multi-degree-of-freedom coupling. Most hinge tubes exhibit unnecessary lateral movements and rotations during bending, making the control unpredictable. Secondly, there is a contradiction between axial stiffness and bending flexibility. Increasing flexibility necessarily sacrifices the thrust and torque transmission capacity. Thirdly, fatigue failure occurs due to stress concentration. The traditional cutting pattern forms stress concentration points at the joints, becoming the origin of fatigue cracks. Engineering analysis shows that the traditional spiral-cut hinge tube generates a lateral swing of up to 15° during bending, and when operating in the fine anatomical area, it may deviate from the target by 3-5 millimeters. Finite element simulation indicates that the stress concentration coefficient of the traditional design is 3.2-4.5, while the new interlocking design can be reduced to 1.8-2.2.

Core Technological Innovation

1. Bionic interlocking puzzle structure: Inspired by the facet joints of the human spine, a two-way interlocking puzzle-like cutting pattern was designed. Each joint unit is composed alternately of convex and concave structures, with the convex part embedded in the concave part to form mechanical interlocking. This design limits movement to a single plane while dispersing stress through surface contact, reducing the stress concentration coefficient by 55%. The joint gap is precisely controlled at 15 ± 1 micrometers, ensuring smooth and unobstructed movement.
2. Variable stiffness gradient design: A stiffness gradient is designed along the length of the tube. The proximal segment uses a high-stiffness pattern (low joint density and large wall thickness), providing thrust and torque transmission; the middle segment uses a medium-stiffness pattern, balancing control and support; the distal segment uses a high-flexibility pattern (high joint density and small wall thickness), achieving large-angle deflection. Through parametric modeling to optimize the stiffness distribution, the device maintains the optimal shape when passing through the curved anatomical path.
3. Integrated wire guiding channels: A dedicated wire guiding channel is designed inside the tube wall, formed by laser cutting into a semi-closed guide rail. The inner surface of the channel is specially polished (Ra ≤ 0.05 micrometers), reducing wire friction. The cross-section of the channel is optimized to be elliptical-like, forming line contact rather than point contact with the circular wire, reducing the friction coefficient from 0.15 to 0.08. The guiding channel ensures that the wire always moves along the preset path, eliminating lateral deviation.

Mechanism of Action

The core of innovative structural design lies in "decoupling and optimization". In terms of kinematic decoupling, the interlocking puzzle structure eliminates lateral degrees of freedom through geometric constraints, enabling pure planar motion; when the wire is tightened, the convex and concave structures interlock with each other, forming a rigid connection, which transmits thrust and torque. In terms of mechanical optimization, the variable stiffness design enables the instrument to adapt to the requirements of different anatomical segments: in the straight segment (such as the middle segment of the ureter), high stiffness is required to maintain the shape stability; in the curved segment (such as the renal pelvis-ureter junction), appropriate flexibility is needed to accommodate the anatomy; in the target area (such as the renal calyx), high flexibility is required to achieve large-angle deflection. In terms of fluid dynamics, the optimized cutting pattern reduces flow resistance, with a 25% increase in flow velocity under perfusion conditions and improved visual clarity.

Efficacy Verification

In the simulation anatomical models, the new type of hinge tube performed exceptionally well: in the simulation ureter model, the success rate of the instrument passing through the curved section increased from 82% to 98%; in the simulation heart model, the time for the catheter to reach the target point was shortened by 35%; the deviation accuracy test showed that the deviation between the commanded angle and the actual angle was only 0.2 - 0.5°, and the repeatability accuracy reached 0.1°. In the fatigue test, under the condition of ±90° bending and 3Hz, the new design had a lifespan of 750,000 cycles, which was 2.5 times that of the traditional design. The multicenter clinical study showed that in percutaneous nephrolithotomy, the rate of renal calyx entry increased from 76% to 92%; in prostate laser enucleation, the tissue resection efficiency increased by 30%; in atrial fibrillation ablation surgery, the stability of the catheter's adhesion to the tissue increased by 40%. The survey of doctors' operational experience showed that 93% of the surgeons believed that the new design improved the control accuracy and predictability.

Research and Development Strategy and Philosophy

We advocate the innovative concept of "structure serves function, design originates from clinical practice", and have established a CDIO (Clinical Demand - Design - Implementation - Operation) closed-loop R&D system. In the clinical demand stage, through surgical video analysis and doctor interviews, 128 key demand points were extracted; in the design stage, topology optimization and generative design were adopted to find the optimal structure under functional constraints; in the implementation stage, rapid prototyping iterations were carried out through additive manufacturing, with each design cycle shortened to 2 weeks; in the operation stage, a clinical feedback database was established to continuously optimize the design. We have established partnerships with 23 top medical centers worldwide, collecting over 500 surgical data each year to drive product iterations. At the same time, we have developed a virtual testing platform based on finite elements, which can predict product performance before production, reducing physical testing by 70%.

Future Outlook

The structural design will evolve towards intelligence, adaptability, and personalization. We are developing "variable stiffness" hinge tubes, which can achieve real-time stiffness adjustment during the operation through electroactive materials or shape memory alloys; developing "multi-plane" hinge tubes, which can independently deflect in two orthogonal planes through wire drawing combinations; exploring "biological peristaltic" structures to simulate intestinal peristaltic waves for self-propulsion. In 2028, we will launch intelligent hinge tubes with "tactile feedback", which can sense tissue contact force through fiber optic grating sensors and feed the information back to the operating handle. Looking further ahead, based on 4D printing, "growth-type" structures will become possible. The instruments can adaptively change their shapes in the body according to the anatomical environment, achieving true "intelligent adaptation", bringing revolutionary changes to natural cavity surgeries.