Hyun-Joong Chung1
University of Alberta1
Textiles are extreme engineering materials that have been optimized mostly for clothing uses for thousands of years. The properties of the wonder materials are tunable by varying their fabric patterns, fiber/yarn composition, and constituting materials. In this talk, I will present two examples of utilizing textiles to protective human lives: (i) a wearable sensor that predicts the end-of-life of firefighter’s personal protective garment and (ii) a textile-enforced elastomeric tube that facilitates blood circulation in an ex-vivo heart perfusion (EVHP) device for heart transplant surgery.<br/>ANECDOTE 1: Firefighters’ lives rely much on the performance of fire-resistant garments. While the garment is composed of textiles that perform exceptionally well in terms of maintaining mechanical robustness such as tear resistance, the performance of these textiles degrade slowly by aging. The major acceleration factors for the aging include high temperature, moisture, and ultraviolet (UV) light. The most serious problem of the aging behavior is that it is virtually undetectable; detectable consequences of the aging is the colour change of the textile, but tensile strength of the aged textile at the moment of detection is merely at the 20~30% of that of as-made ones. Whereas the performance limit of the protective textile is at ~50% of performance retention, the aging is a life-threatening problem for firefighters. In order to address the problem, our team is currently developing an end-of-life sensor of protective textiles. The wearable sensor is attached on the firefighter’s protective garment, and undergoes the same life-experiences of the garment including high temperature, UV and water exposure, and laundering cycles. In the presentation, the design concept of the end-of-life sensor, which includes graphene-based conductive tracks and a sacrificial polymer layer, will be discussed. Understanding and quantifying the degradation of the sacrificial polymer is important. Here, we studied thermally- and hydrothermally-induced aging behavior of high performance polymers by quantifying the gradual loss of tensile strength and elongation at break. Time-temperature superposition principle was used as a framework to quantify the activation energy of degradation. Chemical degradation mechanism was studied by FT-IR with hypothesis-driven and machine-learning assisted methods to elucidate the vulnerable chemical bonding for degradation.<br/>ANECDOTE 2: EVHP is an innovative technology in which a donor heart is kept alive and beating outside of the human body. During EVHP, the organ is kept near body temperature (37 °C) and perfusate (enriched blood) flows through the heart chambers, simulating physiological conditions. Currently, overly stiff tubing used in EVHP devices causes premature pressure wave reflection during heartbeat, which can increase risk of donor organ rejection. Use of aorta-inspired compliant tubing for EVHP devices, namely, RTV silicone elastomer tubes ‘jacketed’ by a sleeve of knitted fabric, was hypothesized to potentially mitigate this problem. We used a custom-built flow loop to pump fluid into sections of compliant tubing at known pressures and measured the response; our main finding was that the tubes deform rapidly as pressure initially increases, but eventually display ‘self-regulation’ behavior where their continued distension is tempered by the stiffening of fibres in the fabric. The experimental findings were supported by our 3-dimensional finite element simulations in ABAQUS using material coefficients obtained from uniaxial tensile tests of the tubing materials. Finally, we will showcase the efficacy of the fabric-jacketed tube in facilitating blood circulation in EVHP devices.