Design strategies for flexible core biopsy needles: insights from patent literature

Flexible biopsy needles are essential for minimally invasive cancer diagnostics, enabling core biopsy sampling through endoscopic and catheter-based procedures. These approaches allow clinicians to access deep-seated or anatomically challenging lesions while reducing patient risk compared to traditional percutaneous methods. However, the shift toward minimally invasive techniques imposes competing design demands on the biopsy needle tip, which must be miniaturized and flexible enough to navigate narrow lumens while maintaining cutting efficiency and retaining adequate tissue samples for clinical diagnosis. This review presents a patent-based analysis of flexible core biopsy needle designs, focusing on mechanisms at the needle tip that govern tissue cutting and retention. We systematically evaluated 65 international patent applications and developed a classification framework for cutting and gripping strategies. Using this framework, we identified dominant technological trends and highlighted underexplored concepts. Forward-cutting tips combined with suction or macroshape grips that engage the sample from the front dominate current designs due to their mechanical simplicity. However, alternative approaches such as compliant tip designs and multidirectional cutting mechanisms offer opportunities to enhance tissue yield without increasing device diameter. Implementing these innovations could reduce the need for repeated insertions, improve sampling efficiency, and enable access to lesions previously considered unreachable. This review provides an overview of flexible core biopsy needle designs and offers insights to guide future innovations that advance minimally invasive cancer diagnostics.