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Abstract BackgroundConventional needles lack active mechanisms for large tip deflection to bypass obstacles or guide through a desired trajectory in needle‐based procedures, compromising accuracy and effectiveness. MethodsAn active needle with a shape memory alloy (SMA) actuator was designed and evaluated by demonstrating deflections in tissue‐mimicking gels. Finite element simulation and real‐time needle tip deflection tracking in tissue‐mimicking gels were performed. ResultsThe active needle deflected 50 and 39 mm at 150 mm insertion depth in the liver and prostate mimicking gels, respectively. Reasonable simulation errors of 16.42% and 12.62% in needle deflections and small root mean squared errors of 1.42 and 1.47 mm in deflection tracking were obtained. ConclusionsThe proposed needle produced desirable large tip deflections capable of bypassing obstacles in the insertion path and tracked a preplanned trajectory with minor errors. The finite element study would help optimise needle designs and predict deflections in soft tissues.
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Controlling Mesenchyme Tissue Remodeling via Spatial Arrangement of Mechanical Constraints
Tissue morphogenetic remodeling plays an important role in tissue repair and homeostasis and is often governed by mechanical stresses. In this study, we integrated an in vitro mesenchymal tissue experimental model with a volumetric contraction-based computational model to investigate how geometrical designs of tissue mechanical constraints affect the tissue remodeling processes. Both experimental data and simulation results verified that the standing posts resisted the bulk contraction of the tissues, leading to tissue thinning around the posts as gap extension and inward remodeling at the edges as tissue compaction. We changed the geometrical designs for the engineered mesenchymal tissues with different shapes of posts arrangements (triangle vs. square), different side lengths (6 mm vs. 8 mm), and insertion of a center post. Both experimental data and simulation results showed similar trends of tissue morphological changes of significant increase of gap extension and deflection compaction with larger tissues. Additionally, insertion of center post changed the mechanical stress distribution within the tissues and stabilized the tissue remodeling. This experimental-computational integrated model can be considered as a promising initiative for future mechanistic understanding of the relationship between mechanical design and tissue remodeling, which could possibly provide design rationale for tissue stability and manufacturing.
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- PAR ID:
- 10320056
- Date Published:
- Journal Name:
- Frontiers in Bioengineering and Biotechnology
- Volume:
- 10
- ISSN:
- 2296-4185
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3389/fbioe.2022.833595
