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This study investigates mosquito proboscis-inspired (MPI) insertion applied to the clinically used biopsy needle to reduce tissue deformation and organ displacement. Advanced medical imagining has enabled early-stage identification of cancerous lesions that require needle biopsy for minimally invasive tissue sampling and pathological analysis. Accurate cancer diagnosis depends on the accuracy of needle deployment to the targeted cancerous lesion site. However, currently available needle delivery systems deform and move soft tissue and organs, leading to a non-diagnostic biopsy or undersampling of the target. Two features inspired by the mosquito proboscis were adopted for MPI insertion in prostate biopsy: (1) the harpoon-shape notches at the needle tip and (2) reciprocating needle-cannula motions for incremental insertion. the local tissue deformation and global prostate displacement during the MPI vs. traditional direct insertions were quantified by optically tracking the displacement of particle-embedded tissue-mimicking phantoms. Results show that the MPI needle insertion reduced both local tissue deformation and global prostate displacement because of the opposite needle-cannula motions and notches which stabilized and reduced the tissue deformation during insertion. Findings provide proof of concept for MPI insertion in the clinical biopsy procedures as well as insights of needle-tissue interaction for future biopsy technology development. Mosquito proboscis is an ideal needle device which minimizes the deformation and displacement of surrounding tissue during insertion for accurate guidance to targeted vessels. The proboscis has a hollow labrum (about 25 μm wide) and two maxillae (about 15 μm wide) with harpoon-shape notches on the side 1 as shown in Fig. 1a. During insertion, the proboscis advances incrementally with vibratory relative displacements of the labrum and maxillae for reciprocating tissue penetration 2,3. A study proposed the mechanism of proboscis insertion 1 as illustrated in Fig. 1b. In Step 1, the left maxilla moves forward into the tissue while the labrum retracts a shorter distance in the opposite direction. In Step 2, the labrum moves forward while the maxillae retract utilizing their notches to anchor the surrounding tissue. The forward motion of the right maxilla and backward motion of the labrum in Step 3 mirror the motions in Step 1. In Step 4, movements of both maxillae and the labrum in Step 2 are repeated. After moving the left maxilla forward and the labrum backward in Step 5, the relative positions of the maxillae and labrum are the same as in Step 1. At this state, the proboscis has moved forward by a distance marked by the wide arrow in Fig. 1b. By repeating the above steps, the proboscis incrementally advances with vibratory motions. The vibratory reciprocating motions of mosquito proboscis have been found to reduce insertion force and resultant tissue deformation 3,4. The harpoon-shape notches of the maxillae may further provide critical support and anchoring to reduce tissu...

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Heat generation during insertion of Kirschner wires (K-wires) may lead to thermal osteonecrosis and can affect the construct fixation. Unidirectional and oscillatory drilling modes are options for K-wire insertion, but understanding of the difference in heat generation between the two modes is lacking. The goal of this study was to compare the temperature rise during K-wire insertion under these two modes and provide technical guidelines for K-wire placement to minimize thermal injury. Ten orthopedic surgeons were instructed to drill holes on hydrated ex vivo bovine bones under two modes. The drilling trials were evaluated in terms of temperature, thrust force, torque, drilling time, and tool wear. The analysis of variance showed that the oscillatory mode generated significantly lowered peak bone temperature rise (13% lower mean value, p = 0.036) over significantly longer drilling time (46% higher mean time, p < 0.001) than the unidirectional mode. Drilling time had significant effect on peak bone temperature rise under both modes (p < 0.001) and impact of peak thrust force was significant under oscillatory mode (p < 0.001). These findings suggest that the drilling mode choice is a compromise between peak temperature and bone exposure time. Shortening the drilling time was the key under both modes to minimize temperature rise and thermal necrosis risk. To achieve faster drilling, technique analysis found that "shaky" and intermittent drilling with moderate thrust force are preferred techniques by small vibration of the drill about the K-wire axis and slight lift-up of the K-wire once or twice during drilling.