A Hybrid Compliant-Tendon Laparoscopic Instrument for Distal Articulation and Grasping: Design and Experimental Validation.

BACKGROUND

Conventional laparoscopic instruments provide limited dexterity in confined anatomical environments, whereas existing articulated designs rely on complex rigid joints or motorised actuation, increasing mechanical complexity and limiting miniaturisation.

METHODS

A hybrid compliant-tendon laparoscopic instrument was developed to integrate articulated distal motion and active grasping within a 5 mm form factor. The compliant segment was fabricated from super-elastic Nitinol, and grasping was achieved using a tendon-pulley mechanism. The system was evaluated using nonlinear finite element analysis and experimental testing, including digital image correlation and benchtop force measurements.

RESULTS

The mechanism achieved up to 75° articulation with mean model errors below 8%. The grasper produced a maximum force of 13.2 ± 0.47 N and maintained performance across articulation angles. Pull-out tests confirmed stable interaction with soft-tissue analogues.

CONCLUSIONS

The proposed design demonstrates a compact, low-complexity approach for combining compliant articulation and tendon-driven grasping within a 5 mm surgical instrument.