A single-use haptic palpation probe for locating subcutaneous blood vessels in robot-assisted minimally invasive surgery

We present the design and evaluation of a novel low-cost palpation probe for Robot assisted Minimally Invasive Surgery (RMIS) for localizing subcutaneous blood vessels. It measures probe tip deflection using a Hall Effect sensor as the spherical tip is moved tangentially across a surface under automated control. The probe is intended to be single-use and disposable, built from 3D printed parts and commercially available electronics. The prototype has a cross-section of less than 15mm×10mm and fits on the end of an 8mm diameter needle driver in the Intuitive Surgical da Vinci^® Research Kit (dVRK). We report experiments for quasi-static sliding palpation with silicone based tissue phantoms with embedded cylinders as subcutaneous blood vessel phantoms. We analyzed signal-to-noise ratios with multiple diameters of silicone cylinders (1.58-4.75 mm) at varying subcutaneous depths (1-5 mm) with a range of indentation depths (0-8 mm) and sliding speeds (0.5-21 mm/s). Results suggest that the probe can detect subcutaneous structures in phantoms of diameter 2.25 mm at a depth of up to 5mm below the tissue surface.