Characterizing tissue stiffness at the tip of a rigid needle using an opto-mechanical force sensor

Area of Science:

• Biomedical Engineering
• Materials Science
• Medical Devices

Background:

• Accurate measurement of tissue mechanical properties is crucial for surgical navigation and diagnosis.
• Existing methods for in-situ stiffness measurement are often limited in resolution and applicability during needle insertion.

Purpose of the Study:

• To develop and validate a novel miniaturized device for measuring Young Modulus at the tip of a needle.
• To assess the device's capability in detecting stiffness variations and tissue boundaries during insertion.

Main Methods:

• A miniaturized cantilever spring integrated into a 5 mm needle tip.
• Interrogation of the cantilever using Fabry-Pérot optical fiber interferometry.
• Controlled repetitive contact with the sample via a piezoelectric actuator and steel cable.

Main Results:

• The device successfully measured Young Modulus at the needle opening.
• Demonstrated detection and quantification of stiffness variations in a gelatin phantom.
• Accurately located tissue boundaries in bovine liver tissue embedded in gelatin.

Conclusions:

• The developed needle-based device offers a promising tool for in-situ mechanical property assessment.
• This technology has potential applications in surgical guidance and tissue characterization.