The influence of autoinjector applied force and shield size on abdominal skin and subcutaneous tissue deformation – An in-vivo ultrasound and digital image correlation study

IF 3.5 2区医学 Q2 ENGINEERING, BIOMEDICAL

Journal of the Mechanical Behavior of Biomedical Materials Pub Date : 2025-09-02 DOI:10.1016/j.jmbbm.2025.107186

Anne-Sofie Madsen Staples , Adam Bo Mandel , Leyre Azcarate , Marie Sand Traberg

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引用次数: 0

Abstract

Background

Shield-triggered autoinjectors (AIs) aim to reduce needle phobia and accidental needlestick injuries and improve usability. However, they may cause deeper injections due to tissue compression. This study investigates the mechanical response of AI application into abdominal tissue in-vivo.

Methods

Tissue thickness/compression level, skin strain, and indentation depth were measured in 10 healthy participants. Digital image correlation (DIC) captured the skin surface, while an ultrasound (US) probe attached to a 3D-printed shield recorded the underlying skin and subcutaneous tissue (SCT) during application of forces up to 20 N using two indenter sizes (Ø15 mm and Ø30 mm).

Results

Increased force correlated with reduced skin + SCT layer thickness; however, a non-linear tissue lockup/plateau around 8–10 N was evident. The Ø30 indenter caused a 45 % mean compression, while the Ø15 resulted in 55 %. ANOVA revealed statistical differences between shield sizes for indentation depth and skin + SCT thickness reduction (p < 0.05). ANOVA further revealed a statistical difference between mean indentation depth for Ø15 (50.39 mm) versus Ø30 (34.84 mm) (p < 0.05). Average strain rates were higher (10.5 % versus 15 %) and skin surface deflection curves were steeper for Ø15 compared to Ø30.

Conclusions

Skin + SCT compression increases until it reaches a lock-up state, but indentation depth responds linearly to increases in force. The high level of tissue compression will increase the risk of intramuscular injections when using shield-triggered AIs, depending on needle length, activation force, and shield size. Therefore, increasing shield sizes to reduce tissue compression and indentation depth can enhance user experience and the probability of reaching the subcutaneous layer. Conclusions are drawn from a small, homogenous cohort, and although the trends are clear, variation between participants highlight the complex nature of human skin tissue. More user groups and injection sites should be investigated.

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自动注射器施加力和屏蔽尺寸对腹部皮肤和皮下组织变形的影响——体内超声和数字图像的相关性研究

背景屏蔽触发式自动注射器（AIs）旨在减少针刺恐惧症和意外针刺伤害，提高可用性。然而，由于组织受压，它们可能导致更深的注射。本研究探讨人工智能在体内腹腔组织中的机械反应。方法测量10例健康受试者的组织厚度/压缩水平、皮肤应变和压痕深度。数字图像相关（DIC）捕获皮肤表面，而连接在3d打印屏蔽上的超声（US）探头在使用两种尺寸的压头（Ø15 mm和Ø30 mm）施加高达20 N的力时记录下皮下皮肤和皮下组织（SCT）。结果力的增加与皮肤+ SCT层厚度的减少相关；然而，在8-10 N附近，明显存在非线性组织锁定/平台。Ø30压头的平均压缩率为45%，而Ø15的平均压缩率为55%。方差分析显示，压痕深度和皮肤+ SCT厚度减少的屏蔽尺寸之间存在统计学差异（p < 0.05）。方差分析进一步显示Ø15 （50.39 mm）与Ø30 （34.84 mm）的平均压痕深度之间存在统计学差异（p < 0.05）。平均应变率更高（10.5% vs 15%），皮肤表面挠度曲线Ø15比Ø30更陡峭。结论skin + SCT压缩增加，直至达到锁定状态，但压痕深度随力的增加呈线性响应。当使用屏蔽触发的ai时，高水平的组织压迫会增加肌肉注射的风险，这取决于针头长度、激活力和屏蔽大小。因此，增加屏蔽尺寸以减少组织压缩和压痕深度可以提高用户体验和到达皮下层的概率。结论是从一个小的同质队列中得出的，尽管趋势是明确的，但参与者之间的差异突出了人类皮肤组织的复杂性。应该调查更多的用户群体和注射部位。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of the Mechanical Behavior of Biomedical Materials 工程技术-材料科学：生物材料

CiteScore

7.20

自引率

7.70%

发文量

505

审稿时长

46 days

期刊介绍： The Journal of the Mechanical Behavior of Biomedical Materials is concerned with the mechanical deformation, damage and failure under applied forces, of biological material (at the tissue, cellular and molecular levels) and of biomaterials, i.e. those materials which are designed to mimic or replace biological materials. The primary focus of the journal is the synthesis of materials science, biology, and medical and dental science. Reports of fundamental scientific investigations are welcome, as are articles concerned with the practical application of materials in medical devices. Both experimental and theoretical work is of interest; theoretical papers will normally include comparison of predictions with experimental data, though we recognize that this may not always be appropriate. The journal also publishes technical notes concerned with emerging experimental or theoretical techniques, letters to the editor and, by invitation, review articles and papers describing existing techniques for the benefit of an interdisciplinary readership.