Wireless Sensors Network for Elder Monitoring Val´ eria Loureiro da Silva † , Member, IEEE,, Fellow, OSA, Charles Lima Soares †‡ , M´ arcio Renˆ e Brand˜ ao Soussa †‡ and Valter de Senna † † SENAI - CIMATEC, Salvador, Brasil, †‡ Centro Universit´ ario Jorge Amado - UNIJORGE, Salvador e-mail: valeria.dasilva@fieb.org.br. Abstract—The population aging associated with the increased number of elderly people living alone bring the need for a remote, non-intrusive system that can allow the elders to safely and independently age in place. This paper proposes and describes a cost effective system that employs a network of passive motion sensors for the elder monitoring and can be used by family and friends. The feasibility of the proposed system in identifying if the person is alive and moving around was demonstrated in the houses of two elderly volunteers. The captured data analysis also shows that the proposed system allows the identification of some elder behaviors related to sleeping pattern and bathroom usage that are correlated to the elders health and well-being. Index Terms—Wireless sensor network, IoT, smart sensors, assisted living, elder monitoring, activity recognition. I. I NTRODUCTION T HE Brazilian population is aging at a much faster rate than what happened in developed countries in the past. The World Health Organization, WHO, estimates that the Brazilian population aging expected in the next 20 years is equivalent to what happened in the last 100 years in some European countries [1]. Additionally, data from IBGE show a significant increase in the number of people that live alone in Brazil, from 9.2% in 2001 to 12.4% in 2011, with 42.3% of these households being occupied by elderly residents [2]. The trend in the increase of elderly people living in single- person households can be explained by the population aging, lack of institutions or elder care communities with long term residence capability and a desire by the elders o maintain their independence [3], [4], [5], [6], [7]. However, this trend brings some problems as the aging process also increases the individual vulnerability since it is usually accompanied by gradual loss in the physical, mental and cognitive capacity [1]. Therefore, it is desirable to have a remote monitoring system for the elderly person that lives in a single-household, with the objective of identifying situations that pose a risk to his or hers health and wellbeing, allowing the elder to age safely and independently in his or hers own house. Recent developments in the technology has enabled a range of diverse applications for smart sensors and IoT, like the control of industrial processes, the study of sand dunes systems [8], monitoring of natural disasters [9] and climate changes[10], forestry inventory [11], and monitoring of patients vital signs [12], [13], [14]. Applications to the monitoring of the older population has been investigated by several research groups [15], [16]. The monitoring of the elder daily activities can be an important tool for preventive care that would allow the elder to safely age in place [17], [18], [19], [20], [21]. For example, Rantz et al. showed that alerting family and nurses of small changes in an elder behavior enabled the diagnose of health problems 10 days earlier than the time it would take for the elder to notice it [22], [23], [24]. However, not all the investigated technologies were well accepted by the elderly population. Published research in this area indicates that the elder population doesn’t like image recording sensors as they feel it invades their privacy and modesty [17], [25], [26], [27], [28]. Wearable sensor or sensors that require the elder activation are often forgotten to be used or are taken out at important moments like shower or bath time [19], [22], [25], [28]. Passive ambient sensors, like the ones base on passive infrared (PIR) technology, are better accepted by the elderly populations, as they do no record images, are small and unobtrusive [23], [26], [29], [30] and have been investigated by a number of researchers [17], [19], [26], [31], [32], [33], [34]. In Brazil, elder care is usually done by the family and when that is not possible or available, it is done by friends and neighbors [3], [4], [5], [6], [7]. That is a different reality than the one in developed countries where assisted community living exists and health professionals are available at all times to monitor and assist the elders as needed. The research work mentioned in the previous paragraphs were tailored for this type of environment and to be used by the health professionals. Those systems would have a very limited application in Brazil. The research described in the present paper, is tailored for the Brazilian reality, and describes the development of a non- intrusive monitoring system that can be used by family and friends of the elder person. Its objective is to be accessible to a wide demographic and therefore, needs to be low cost, of easy maintenance and installation and transparent to the elder, not requiring that the elder interacts with the system. The approach taken in this research, consists of the deploy- ment of a wireless PIR sensor network in the elder residence that communicates with a remote center where the data can be analyzed and alarms sent when risky situations are identified. The type of sensor used was limited to a PIR motion sensor, which is low cost and widely available. Using a single sensor type reduces the complexity of installation and maintenance costs. Additionally, the motion sensors do not record any images and preserve the elder privacy. The research reported in this paper aims at answering a primary question: can such a minimalist system provide the information needed to tell if the elder is alive and moving around with the minimum RTIC - REVISTA DE TECNOLOGIA DA INFORMAÇÃO E COMUNICAÇÃO , VOL. 8, NO. 2, OUTUBRO 2018 15