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© 2021 The Textile Institute.Cardiac patch has been proposed as an alternative therapeutic tissue engineering strategy to treat damaged heart for patients who survive the acute myocardial infarction (MI). To that end, studies have focused on designing an ideal cardiac patch assisting myocardium to repair itself. The engineering of three dimensional (3 D) anisotropic knitted scaffolds could be an efficient and effective strategy for cardiac patches. Thus, the polyethylene terephthalate (PET) pile loop knit fabrics were fabricated as 3 D scaffolds, where the values of stiffness (Young’s modulus) of the scaffolds were similar to those reported for the human myocardium. Anisotropic porous knitted scaffolds supported the adhesion and proliferation of murine C2C12 myoblasts cell line in vitro. Scaffolds with a high surface to volume ratio and porosity exhibited superior performance in terms of cell adhesion and proliferation. Furthermore, out of thirteen proinflammatory cytokines, the levels of three cytokines including IL-1α, IL-1β, and IL-11 were observed to be higher in cells seeded on scaffolds coated with fibronectin than those in related control groups. Thus, the proposed knitted structure can potentially be used for tissue engineering and regenerative medicine.

In our previous publications, the response of perfluorinated (PF) graded index (GI) POFs (62.5/750, 62.5/490m) to bending, tensile loading, and cyclic loading was investigated. The results showed that Cytop-1 (62.5/750m) was more appropriate to be used as an optical fiber sensor for automotive seat occupancy sensing relative to Cytop-2 (62.5/490m). In this study, a textile-based optical fiber sensor was designed and the effect of automotive seat covering including face material and foam backing on a sensor's performance was analyzed. The pressure interval under which the proposed POF sensor design could perform well was found to be between 0.18 and 0.21N/cm(2), where PF GI POF (62.5/750m) was used as the POF material. The responses of the sensor in this interval were observed to be accurate and reproducible. The face fabric structure and the thickness of foam backing were not found to be significant factors to change the sensor response. Artificial neural network (ANN) was used for data analysis, and Qwiknet (version 2.23) software was used to develop ANNs. According to the results of Qwiknet, the prediction performances for training and testing data-sets were 75 and 83.33%, respectively.

The goal of this research aimed to develop an accurate and reproducible textile-based optical fiber sensor for automotive seat occupancy. In our previous publication, the response of perfluorinated (PF) graded index (GI) polymer optical fibers (POFs) (62.5/750 and 62.5/490m) to bending and tensile loading was investigated. In this study, the response of the PF GI POFs to cyclic loading was investigated. The repeated loading and unloading the POF sensor would experience due to car vibrations and multiple uses by seat occupants, might cause fatigue failure to the POF sensor. The results showed that the Cytop-1 did not show any permanent deformation up to 500 cycles at strain rates 4 and 60mm/min at a gage length of 76.2mm in its elastic sensitive strain region. The Cytop-2 showed permanent deformation at 3.5% strain after 500 cycles at a gage length of 76.2mm. Thus, the Cytop-1 was found out to be more appropriate to be used as an optical fiber sensor for automotive seat occupancy sensing relative to the Cytop-2. In this study, a theoretical approach of the behavior of PF GI POF to cyclic loading was also provided.

The automotive industry is a promising area for innovations in the field of polymer optical fiber (POF) sensors as the industry currently uses the POF mostly for data transmissions. Since an optical fiber sensor has a high bandwidth, is small in size, is lightweight, and is immune to electromagnetic interference, it offers higher performance than that of its electrical-based counterparts such as the strain gage, elastomeric bladder, and resistive sensor systems. This enhanced performance makes an optical fiber sensor a suitable material for sensing seat occupancy for improved safety features in automobiles. The overall goal of this research is to develop a textile-based optical fiber sensor for automotive seat occupancy with high accuracy and reproducibility. In this study, the bending and tensile loading responses of POF were investigated, where two perfluorinated (PF) graded index (GI) POFs with two different core/cladding diameters, 62.5/750 and 62.5/490m, were used. The bending loss and the light attenuation against the applied axial stress were measured by a photon counting optical time-domain reflectometer. The critical bending diameters were analyzed: Cytop-1 (62.5/750m)38.10mm, Cytop-2 (62.5/490m)44.45mm. Furthermore, the elastic sensitive strain regions (x), where the stress-induced loss was recoverable, of the POFs at a 76.2mm gage length at a strain rate of 4mm/min were determined: Cytop-1: 3%x3.5%, Cytop-2: 3.1%x3.3%. The Cytop-1 was found to be less sensitive to bending and to have greater elastic sensitive strain range relative to the Cytop-2. In this study, a theoretical approach of the PF GI POF behavior to bending and axial tension was provided. The results demonstrated the feasibility of POFs as optical fiber sensors for automotive seat occupancy sensing.