End-cut needle biopsy procedure of capturing tissue.
Definitions of inclination angle (λ) and rake angle (α) on a two-plane symmetric needle tip.
Regular two-plane symmetric needle defined by the bevel angle ξ.
Inclination (λ) and rake angle (α) of regular two-plane symmetric needle and ECE two-plane needle.
(a) ECE two-plane needle with a continuous cutting edge and (b) ECE two-plane needle with a discontinuous cutting edge.
ECE two-plane needle in (a) isometric view (b) side view, and (c) top view.
(a) Side view and (b) top view of needle tip exposed to initial tissue cutting.
Experimental setup for needle insertion into bovine liver.
Regular two-plane symmetric and ECE needles used for experiments.
Needle insertion into bovine liver force example of ECE needle with ξ = 20°.
Biopsy sample length comparing ECE two-plane needles to regular two-plane needles.
Biopsy sample length comparing pressure effect for (a) regular and (b) ECE two-plane needles.
Internal wall friction force repels the motion of the incoming tissue while the vacuum force helps to pull the sample into the needle.
Needle insertion force comparing ECE two-plane needles to regular two-plane needles.
Needle insertion force comparing pressure effect for (a) regular and (b) ECE two-plane needles.
Force model prediction with given S factors for regular two-plane and ECE needles.
The effect of needle vacuum pressure on S factor.
Needle insertion force compared to biopsy length with least squares best fit lines for needle pressures of (a) 0 kPa, (b) −33.9 kPa, and (c) −67.7 kPa.
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