Please cite this article in press as: Kitamura K, et al. Development of a novel pulse wave velocity measurement system: Using dual piezoelectric elements. Med Eng Phys (2014), http://dx.doi.org/10.1016/j.medengphy.2014.02.024 ARTICLE IN PRESS G Model JJBE-2441; No. of Pages 6 Medical Engineering & Physics xxx (2014) xxx–xxx Contents lists available at ScienceDirect Medical Engineering & Physics jo ur nal ho me p ag e: www.elsevier.com/locate/medengphy Technical note Development of a novel pulse wave velocity measurement system: Using dual piezoelectric elements Kei-ichiro Kitamura a,∗ , Ryuya Takeuchi a , Kazuhiro Ogai b , Zhu Xin c , Wenxi Chen c , Tetsu Nemoto a a Department of Clinical Laboratory Science, Graduate School of Medical Science, Kanazawa University, Kanazawa, Ishikawa 920-0942, Japan b Department of Molecular Neurobiology, Graduate School of Medicine, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan c Biomedical Information Technology Laboratory, Graduate Department of Computer and Information Systems, The University of Aizu, Aizuwakamatsu, Fukushima 965-8580, Japan a r t i c l e i n f o Article history: Received 19 September 2013 Received in revised form 21 February 2014 Accepted 23 February 2014 Keywords: Brachial-ankle pulse wave velocity Dual piezoelectric sensor Non-invasive measurement a b s t r a c t The aim of this study is to develop a painless system of measuring the brachial-ankle arterial pulse wave velocity (baPWV) without compression cuffs. The PWV reflects the compliance of the artery and is measured for the early diagnosis of arteriosclerotic vascular diseases. However, the conventional baPWV system, which measures four cuff pressures simultaneously, easily causes circulation block and tightening pain at the extremities. In addition, approximately 15 min are required to stabilise the blood pressure for re-examination. Therefore, we developed a novel baPWV measurement system using dual piezoelectric sensor elements. The principle of this high-sensitivity pressure pulse detection system is based on adding the two in-phase outputs from the coaxially arranged dual piezoelectric sensor. As our system facilitates the measurement of the baPWV by detecting the pulsation of an artery using sensors fixed on the skin where the pulse is palpable, it does not cause pain and reduces examination time. The coefficients of correlation between the baPWV values obtained from the conventional and present methods were 0.93 (right side) and 0.90 (left side). The results suggest that our system can be used to measure the baPWV without pressure cuffs as accurately as the conventional method. © 2014 IPEM. Published by Elsevier Ltd. All rights reserved. 1. Introduction In biomechanics, if the peripheral arterial segment is mod- elled as a thin-walled, isotropic, incompressible tube containing an incompressible fluid, the conduction velocity of the pressure wave travelling through the tube is related to the wall elastic parameter (stiffness) according to the Moens–Korteweg equation [1,2]: Conduction velocity of the pressure wave =  E × h 2r where h is the wall thickness, r is the lumen radius, E is the stiffness, and  is the blood density. The Moens–Korteweg equation implies that the conduction velocity of the pressure wave is proportional to the square root of the incremental stiffness E of the vessel wall. With an increase in the stiffness, the travelling speed of the pres- sure wave in the wall increases. Arterial pulse wave velocity (PWV) ∗ Corresponding author. Tel.: +81 076 265 2595; fax: +81 076 234 4369. E-mail address: kkitamur@staff.kanazawa-u.ac.jp (K. Kitamura). refers to the pressure wave velocity along the artery and is hence an index of arterial stiffness, which represents arteriosclerotic vas- cular change even at an early stage of the disease. Moreover, a systematic meta-analysis of prospective observational data from 17,635 subjects showed that PWV may enable better identification of high risk populations who may benefit from more aggressive cardiovascular risk factor management [3]. Therefore, we believe that measurement of PWV is very important in the evaluation of cardiovascular risk factor. Brachial-ankle PWV (baPWV) is the one of the prevailing tech- nique of PWV to assess arterial stiffness using pressure cuffs wrapped on the bilateral brachium and ankles [4–6]. However, this methodology requires applying simultaneous compression to the four extremities with blood pressure cuffs. Sometimes, such compression of all extremities can cause transient sympathetic hypertonia associated with tightening pain. In addition, when a re-examination is necessary, approximately 15 min are required to stabilise the condition of blood pressure. We recently developed a highly sensitive biological vibration detection device using a coaxially designed dual piezoelectric sen- sor. This device enables aortic pulsation to be captured by placing http://dx.doi.org/10.1016/j.medengphy.2014.02.024 1350-4533/© 2014 IPEM. Published by Elsevier Ltd. All rights reserved.