A Novel Remote Health Monitor with Replaceable Non-Fragile Bio-Probes on RFID Tag

Lin, Jium Ming; Chang, Po Kuang

doi:10.4028/www.scientific.net/amm.145.415

Cited by 1 publication

(1 citation statement)

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“…This use of this method for measurement and analysis of the in vivo mechanical behavior of microprobes is not limited to the PVAc-NC class of materials. Additional potential applications include monitoring the degradation rate of biodegradable materials 22 and characterizing the mechanical behavior of biological tissues 23,24 , as well as characterization of microscale structures for non-biological applications. Further, additional environmental controls can be added (e.g.…”

Section: Discussionmentioning

confidence: 99%

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for <em>ex vivo</em> Characterization

Hess¹,

Potter

Tyler

et al. 2013

JoVE

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Implantable microdevices are gaining significant attention for several biomedical applications [1][2][3][4] . Such devices have been made from a range of materials, each offering its own advantages and shortcomings 5,6 . Most prominently, due to the microscale device dimensions, a high modulus is required to facilitate implantation into living tissue. Conversely, the stiffness of the device should match the surrounding tissue to minimize induced local strain [7][8][9] . Therefore, we recently developed a new class of bio-inspired materials to meet these requirements by responding to environmental stimuli with a change in mechanical properties [10][11][12][13][14] . Specifically, our poly(vinyl acetate)-based nanocomposite (PVAc-NC) displays a reduction in stiffness when exposed to water and elevated temperatures (e.g. body temperature). Unfortunately, few methods exist to quantify the stiffness of materials in vivo 15, and mechanical testing outside of the physiological environment often requires large samples inappropriate for implantation. Further, stimuli-responsive materials may quickly recover their initial stiffness after explantation. Therefore, we have developed a method by which the mechanical properties of implanted microsamples can be measured ex vivo, with simulated physiological conditions maintained using moisture and temperature control 13,16,17 .To this end, a custom microtensile tester was designed to accommodate microscale samples 13,17 with widely-varying Young's moduli (range of 10 MPa to 5 GPa). As our interests are in the application of PVAc-NC as a biologically-adaptable neural probe substrate, a tool capable of mechanical characterization of samples at the microscale was necessary. This tool was adapted to provide humidity and temperature control, which minimized sample drying and cooling 17. As a result, the mechanical characteristics of the explanted sample closely reflect those of the sample just prior to explantation.The overall goal of this method is to quantitatively assess the in vivo mechanical properties, specifically the Young's modulus, of stimuliresponsive, mechanically-adaptive polymer-based materials. This is accomplished by first establishing the environmental conditions that will minimize a change in sample mechanical properties after explantation without contributing to a reduction in stiffness independent of that resulting from implantation. Samples are then prepared for implantation, handling, and testing ( Figure 1A). Each sample is implanted into the cerebral cortex of rats, which is represented here as an explanted rat brain, for a specified duration (Figure 1B). At this point, the sample is explanted and immediately loaded into the microtensile tester, and then subjected to tensile testing ( Figure 1C). Subsequent data analysis provides insight into the mechanical behavior of these innovative materials in the environment of the cerebral cortex. Video LinkThe video component of this article can be found at http://www.jove.com/video/50078/ Protocol 1. Sample P...

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Section: Discussionmentioning

confidence: 99%