Prediction of Coating Adhesion on Laser-Cleaned Metal Surfaces of Battery Cells Using Hyperspectral Imaging and Machine Learning

Electric vehicles are shaping the future of the automotive industry. The traction battery is one of the most important components of electric cars. To ensure that the battery operates safely, it is essential to physically and electrically separate the cells facing each other. Coating a cell with varnish helps achieve this goal. Current studies use a destructive method on a sampling basis, the cross-cut test, to investigate the coating quality. In this paper, we present a fast, nondestructive and inline alternative based on hyperspectral imaging and artificial intelligence. Therefore, battery cells are measured with hyperspectral cameras in the visible and near-infrared (VNIR and NIR) parts of the electromagnetic spectrum before and after cleaning then coated and finally subjected to cross-cut test to estimate coating adhesion. During the cross-cut test, the cell coating is destroyed. This work aims to replace cross-cut tests with hyperspectral imaging (HSI) and machine learning to achieve continuous quality control, protect the environment, and save costs. Therefore, machine learning models (logistic regression, random forest, and support vector machines) are used to predict cross-cut test results based on hyperspectral data. We show that it is possible to predict with an accuracy of ~75% whether problems with coating adhesion will occur. Hyperspectral measurements in the near-infrared part of the spectrum yielded the best results. The results show that the method is suitable for automated quality control and process control in battery cell coating, but still needs to be improved to achieve higher accuracies.

Construction of transplantable artificial vascular tissue based on adipose tissue-derived mesenchymal stromal cells by a cell coating and cryopreservation technique

Prevascularized artificial three-dimensional (3D) tissues are effective biomaterials for regenerative medicine. We have previously established a scaffold-free 3D artificial vascular tissue from normal human dermal fibroblasts (NHDFs) and umbilical vein-derived endothelial cells (HUVECs) by layer-by-layer cell coating technique. In this study, we constructed an artificial vascular tissue constructed by human adipose tissue-derived stromal cells (hASCs) and HUVECs (ASCVT) by a modified technique with cryopreservation. ASCVT showed a higher thickness with more dense vascular networks than the 3D tissue based on NHDFs. Correspondingly, 3D-cultured ASCs showed higher expression of several angiogenesis-related factors, including vascular endothelial growth factor-A and hepatic growth factor, compared to that of NHDFs. Moreover, perivascular cells in ASCVT were detected by pericyte markers, suggesting the differentiation of hASCs into pericyte-like cells. Subcutaneous transplantation of ASCVTs to nude mice resulted in an engraftment with anastomosis of host’s vascular structures at 2 weeks after operation. In the engrafted tissue, the vascular network was surrounded by mural-like structure-forming hASCs, in which some parts developed to form vein-like structures at 4 weeks, suggesting the generation of functional vessel networks. These results demonstrated that cryopreserved human cells, including hASCs, could be used directly to construct the artificial transplantable tissue for regenerative medicine.

Construction of transplantable artificial vascular tissue based on adipose tissue-derived mesenchymal stromal cells by a cell coating and cryopreservation technique

Prevascularized artificial three-dimensional (3D) tissues are effective biomaterials for regenerative medicine. We have previously established a scaffold-free 3D artificial vascular tissue from normal human dermal fibroblasts (NHDFs) and umbilical vein-derived endothelial cells (HUVECs) by layer-by-layer cell coating technique. In this study, we constructed an artificial vascular tissue constructed by human adipose tissue-derived stromal cells (hASCs) and HUVECs (ASCVT) by a modified technique with cryopreservation. ASCVT showed a higher thickness with more dense vascular networks than the 3D tissue based on NHDFs. Correspondingly, 3D-cultured ASCs showed higher expression of several angiogenesis-related factors, including vascular endothelial growth factor-A and hepatic growth factor, compared to that of NHDFs. Moreover, perivascular cells in ASCVT were detected by pericyte markers, suggesting the differentiation of hASCs into pericyte-like cells. Subcutaneous transplantation of ASCVTs to nude mice resulted in an engraftment with anastomosis of host’s vascular structures at two weeks after operation. In the engrafted tissue, the vascular network was surrounded by mural-like structure-forming hASCs, in which some parts developed to form vein-like structures at four weeks, suggesting the generation of functional vessel networks. These results demonstrated that cryopreserved human cells, including hASCs, could be used directly to construct the artificial transplantable tissue for regenerative medicine.