Beat-by-Beat Monitoring of Systolic Blood Pressure based on an ASIC and a Mobile Phone for Ambulatory Application Wenxi Chen 1 , Ming Huang 1 , Xin Zhu 1 , Kei-ichiro Kitamura 2 and Tetsu Nemoto 2 1 Biomedical Information Technology Laboratory, The University of Aizu, Tsuruga, Aizu-wakamatsu City, Japan 2 Department of Laboratory Science, Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kodatsuno, Kanazawa City, Japan Keywords: Blood Pressure, Electrocardiogram, Photoelectric Plethysmogram, Pulse Arrival Time, Asic, Mobile Phone, Ambulatory Monitoring, Daily Healthcare. Abstract: This paper describes an ambulatory monitor for beat-by-beat monitoring of systolic blood pressure (SBP) based on an ASIC chip and a mobile phone. The ASIC is able to measure electrocardiogram (ECG), photoelectric plethysmogram (PPG), and has a peripheral interface to control an air pump and valve for inflating and deflating a sphygmomanometer cuff in conventional blood pressure measurement. Algorithms for signal processing, characteristic point detection and SBP estimation are implemented on a mobile phone. Pulse arrival time (PAT) is derived from the apex of QRS complex to the maximum slope of PPG, and is used to estimate a rapid change component in SBP beat-by-beat. An oscillometric sphygmomanometer with a cuff is used to determine SBP intermittently for calibration purpose. Data communication between a mobile phone and the ambulatory monitor is conducted via a Bluetooth wireless connection. Performance of the prototype is examined by data from five healthy college students. The results show that 65.9% of estimated SBP fall into ±5% relative error, 96.6% in ±10% and 99.7% in ±15%. This prototype is a pilot study aiming at integrating an innovative sphygmomanometry into a mobile phone for continuous blood pressure monitoring. We expect to find potential applications in ambulatory monitoring and daily healthcare. 1 INTRODUCTION Ambulatory monitoring of multiple vital signs attracts more and more attention in daily healthcare domain. Monitoring devices with smaller size and lighter weight are desirable. With dramatic advancement in information technologies, a mobile phone is nowadays not only a communication tool, but also provides a universal platform with versatile interfaces, large amount of computational power and high capacity of data communication. Widespread utilization of mobile phones in daily life makes it practical and acceptable to extend their applications in ambulatory healthcare by integrating advanced biomedical sensors and functionalities. Ambulatory applications based on mobile phones have been widely explored in various aspects such as diagnosis, monitoring and health management. Without requiring any additional accessories, a built-in camera can be used to monitor breath rate and pulse rate simultaneously by analyzing chest movement during breathing and chromatic tone change due to blood flush during heartbeating in a series of images (Philips, 2011). More professionally, an external device with specific function is connected to a mobile phone via wired or wireless means to turn a mobile phone into a significantly efficient medical checkup equipment. For example, an electrode pad is attached to an iPhone or Android smartphones to monitor ECG and detect heart rate in real-time mode without directly contacting the electrodes to the body surface (AliveCor, 2011). Although it does not serve to diagnose acute myocadial infarction, an ambulatory ECG can mark cardiac events in emergency situation conveniently. A B-mode ultrasound imaging device based on a mobile phone was developed to offer an imaging tool for kidney, liver, eye and uterine screenings (Richard and Zar, 2009). It is realized by simply connecting a portable ultrasound probe to a mobile phone via a USB cable. A mobile phone implements 10 Chen W., Huang M., Zhu X., Kitamura K. and Nemoto T.. Beat-by-Beat Monitoring of Systolic Blood Pressure based on an ASIC and a Mobile Phone for Ambulatory Application. DOI: 10.5220/0004192600100013 In Proceedings of the International Conference on Biomedical Electronics and Devices (BIODEVICES-2013), pages 10-13 ISBN: 978-989-8565-34-1 Copyright c  2013 SCITEPRESS (Science and Technology Publications, Lda.)