Smart-Cuff: A Wearable Bio-Sensing Platform with Activity-Sensitive Information Quality Assessment for Monitoring Ankle Edema Ramin Fallahzadeh * , Mahdi Pedram * , Ramyar Saeedi * , Bahman Sadeghi † , Michael Ong † , and Hassan Ghasemzadeh * * Embedded and Pervasive Systems Laboratory School of Electrical Engineering and Computer Science Washington State University Pullman, WA 99164 USA Email: {rfallahz, mpedram, rsaeedi, hassan}@eecs.wsu.edu † Department of Medicine University of California Los Angeles CA 90095 USA Email: {bsadeghi,mong}@mednet.ucla.edu Abstract—Leg swelling produced by retention of fluid in leg tissues is known as peripheral edema, which is regarded as a symptom for various systematic diseases such as heart or kidney failure. In current clinical practice, edema is manually assessed by clinical experts. Such an assessment can often be inaccurate and unreliable especially if it is made by different operators at different times. Despite the importance of monitoring edema for the purpose of evaluating the course of disease or the effect of treatment, quantifying peripheral edema in a continuous and accurate fashion has remained a challenge. In this paper, we propose a wearable real-time platform (namely, Smart-Cuff), which integrates advanced technologies in sensing, computation, and signal processing and machine learning for continuous and real-time edema monitoring in remote and in-home settings. Given that peripheral edema is highly dependent on various contextual attributes such as body posture, we present an activity- sensitive approach to discard erroneous or contextually invalid sensor data in order to meet the requirements of both energy effi- ciency and quality of information. Examination of our hardware prototype demonstrates the effectiveness of the proposed force- sensitive resistor-based edema sensor (with an R 2 of 0.97 for our regression model) as well as the activity monitoring mechanism (over 99% accuracy) that provide the means to perform reliable data sanity check on ankle circumference measurements in a continuous manner. I. I NTRODUCTION Peripheral edema is one of the primary symptoms of volume overload in the body due to onset or exacerbation of a variety of systemic diseases that could disturb cardiovascular, renal, or hepatic system [1]–[3]. It could also emerge as a side effect of many medications or as a symptom in venous, metabolic, and inflammatory diseases, chronic lymphedema, post-surgery, and pregnancy [1], [2], [4]. Edema secondary to lymphatic or venous diseases of lower limb usually presents as a chronic asymmetric swelling, whereas edema due to systemic diseases such as heart, liver, and renal failure develops symmetrically in both lower limbs [4]. Edema occurs when lymph formation exceeds lymphatic drainage in extra-cellular space [3], [5]. Hypoal-buminemia and increased intra-capillary hydrostatic pressure are considered as the main causes of increased lymph formation [6]. When conducting research in the area of peripheral edema monitoring, the main questions that arises is “where on the body can peripheral edema be monitored most effectively?” While it is feasible to measure peripheral edema from various lower-body locations, it appears that the medical community has reached a unanimity that ankle edema is the best rep- resentative of the peripheral edema. The practicability and dependability of eight different methods of peripheral edema measurement as well as their association with the classic clinical assessment of edema were investigated in [2]. It is concluded that ankle circumference measurement is an almost perfect inter-examiner and intra-examiner agreement in assessment of peripheral edema [2], [7]. Moreover, numerous past studies have confirmed the validity of lower limb edema estimation by means of circumference measurement [8]–[12]. In addition to easiness, circumference-based measurement of lower limb volume is a rapid way for edema changes assess- ment that could be used in substitute of water displacement method [13], [14] which is considered as the gold standard method for this purpose [15]. Therefore, in this paper our goal is to monitor ankle circumference as the most promising assessment in edema monitoring. Monitoring lower limb edema in the clinic is usually straightforward and often subjective. In most cases, after the subject is stabilized in desired position for the preferred amount of time, a human operator uses simple tools and methods such as tape measure to carry out the task. Another method is to apply pressure on the skin with the tip of thumb. The Seventh International Workshop on Information Quality and Quality of Service for Pervasive Computing, 2015 U.S. Government work not protected by U.S. copyright 57