W. H. Lin, F. Chen, Y. Geng, N. Ji, P. Fang, and G. Li, “Towards accurate estimation of cuffless and continuous blood pressure using multi-order derivative and multivariate photoplethysmogram features,” Biomed. Signal Process. Control 63, 102198 (2021). [Crossref] Q. Qananwah, A. Dagamseh, H. Alquran, K. S. Ibrahim, M. Alodat, and O. Hayden, “A comparative study of photoplethysmogram and piezoelectric plethysmogram signals,” Phys. Eng. Sci. Med. 43(4), 1207–1217 (2020). [Crossref] Z. D. Liu, B. Zhou, Y. Li, M.