1
C
Nilanjan Dey
1
, Amira S. Ashour
2
, Fuqian Shi
3
, Simon James Fong
4
, João Manuel R.S. Tavares
5
1
Department of Information Technology, Techno India College of Technology, West Bengal, 740000,
India (email: neelanjan.dey@gmail.com)
2
Department of Electronics and Electrical Communications Engineering, Faculty of Engineering, Tanta
University, Egypt (email: amirasashour@yahoo.com)
3
College of Information & Engineering, Wenzhou Medical University, Wenzhou, 325035, PR China
(e-mail: sfq@wmu.edu.cn)
4
Department of Computer and Information Science Data Analytics and Collaborative Computing
Laboratory University of Macau, Taipa, Macau SAR (ccfong@umac.mo)
5
Instituto de Ciência e Inovação em Engenharia Mecânica e Engenharia Industrial, Departamento de
Engenharia Mecânica, Faculdade de Engenharia, Universidade do Porto, Porto, Portugal (email:
tavares@fe.up.pt)
Abstract— Medical cyber-physical systems (MCPS) are healthcare critical integration of a network of medical
devices. These systems are progressively used in hospitals to achieve a continuous high-quality healthcare. The
MCPS design faces numerous challenges, including inoperability, security/privacy, and high assurance in the system
software. In the current work, the infrastructure of the cyber-physical systems (CPS) are reviewed and discussed.
This article enriched the researches of the networked Medical Device (MD) systems to increase the efficiency and
safety of the healthcare. It also can assist the specialists of medical device to overcome crucial issues related to
medical devices, and the challenges facing the design of the medical device’s network. The concept of the social
networking and its security along with the concept of the wireless sensor networks (WSNs) are addressed.
Afterward, the CPS systems and platforms have been established, where more focus was directed toward CPS-based
healthcare. The big data framework of CPSs is also included.
Keywords— Networked medical device systems, wireless sensor networks, medical internet of things, body area
networks, security assurance, patient monitoring.
1. Introduction
yber physical system (CPS) is an integration of computation, including Cyber world (i.e. computers) and the
physical processes through computer networks. Embedded computers and networks are also involved to monitor and
control the physical processes through feedback loops [1]. Numerous data types are acquired from a real-world
using sensors. These data are then transmitted to the cyber world, processed and analyzed. The idea behind the CPS
is to integrate the intelligence in everyday objects/services to execute critical tasks. The CPS concept has a
significant role for several information technology (IT) -based social service frameworks [2]. It can be applied to
Medical cyber-physical systems: A survey
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social services, especially in medical and healthcare applications [3]. Generally, several countries suffer from dire
shortages of healthcare personnel leading to a drop in the medical care quality and an extensive increase in
healthcare costs. The competences of adapting new devices for health monitoring systems have risen. In healthcare
monitoring, data transmission using low cost sensors and several communication media has directed to a foremost
concern for the prevailing platforms leading to ineffectiveness in processing the massive data amount in real time.
Consequently, in order to improve this field, an infrastructure and computing framework are required. This leads to
Big data processing frameworks for Medical cyber-physical systems (MCPS) which integrate the cyber world
aspects and the real world with dynamic, fully flexible systems for decision making and other healthcare
applications [4] [5].
The current decade witnesses an innovative revolution in communication and computing. In widespread domains,
the Internet has spanned numerous networks with significant impact on every life aspect especially in the medical
domain. The social and economic impacts of the CPS and MCPS systems are immensely superior. Several
investments are completed worldwide to improve this technology. Since the medical data may be transferred
through wireless and/or social networks, the physical components of the devoted systems impose extensive
challenges, such as reliability, security and safety requirements [6]. Such challenges are different from those in
common computing applications. Furthermore, the physical components are qualitatively dissimilar to the common
object-oriented software components. The next network generation will exploit a variety of resources with
substantial sensing abilities to be extended beyond the physical connected computers in order to comprise
multimodal information from cognitive, biological and social networks [7]. This standard modification will include
interdependent social networks (networks of individuals), mobile personal computing, smart devices and
communication devices, which will form cyber-physical social systems (CPSS) or net-centric societies (NCS). It
becomes indispensable to determine the ability of the networking and computing technologies to provide a sufficient
foundation for the MCPS [8] [9]. For alleviating the healthcare problems, technology development is considered a
key role to improve the infrastructures using automated prevalent health monitoring technologies. Such technologies
monitor person’s health and alert the proper healthcare laborers in the emergency cases to offer the optimal care
with nominal management.
Intelligent devices, including wearable devices and smart meters, with considerable sensing and networking
capabilities become emerging. Henceforth, these devices, which are commonly known as the
Internet-of-Things (IoT), will be persistently sensing, monitoring and interpreting the environment [10, 11]. The
association between the IoT and the social networks has an important implication for the innovative computing and
for the communication infrastructure. Commonly, the IoT is limited to monitor and control small devices without
any constraints to have the devices on a common network. However, the CPSs are more interested with how the
physical systems are controlled and monitored using the cyber space. CPSs are exclusively identifiable and can be
connected through the internet, which considered examples of the IoT. For information transfer, the IoT is basically
networking of Cyber-Physical things. Therefore, CPS can be considered the first level and IoT and the second level
of the vertical systems integration. Connected CPSs can be known as IoT. In order to provide real-time monitoring
with feedback control services, sensing, processing and communication platforms can be deeply embedded in
physical processes as a part of larger processes/systems. Such systems in the healthcare domain are called MCPS
that has computing ability and a physical element to improve the healthcare via the comprehension pervasive health
monitoring systems (PHMS). It supports the distributed computing using wireless devices. For smart healthcare,
wireless body area networks (WBANs) have emerged as the foremost technology that offers ubiquitous healthcare
services and real-time health monitoring [12, 13]. The WBANs are considered medical cyber-physical systems that
can operate in impenetrable environments, such as hospitals, leading to high interactive communication interference
in several medical application scenarios. This requires provable behaviors or high-confidence and security.
The main contribution of the current survey is to provide a cutting-edge on MCPS systems and their role in the
healthcare. The structure and platform of the CPS systems based on the WSNs are introduced as it is the milestone
of ant MCPS systems. This survey highlighted the physical infrastructure required for CPS, the CPS general
requirements and the related security issues. In addition, the CPS and MCPS in the social spaces are introduced.
Furthermore, the networked medical device systems and IT-based social services in medical systems are also
addressed. Finally, the recent research directions and challenges in MCPS for future medical devices are discussed.
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2. Cyber-Physical Systems and medical CPS structure
Enormous economic impairment occurs in the case of CPS malfunction which affects the corresponding systems
operation. The CPS has physical infrastructure requirements along with networking models. The CPS becomes more
complex, prevalent, personalized and reliable. The related systems can be used in several real-life applications, such
as smart grids, robotics and healthcare. Improvements in the CPSs will empower the adaptability, capability,
scalability, usability, resiliency, security and safety producing completely different system than the simplest
embedded systems. The common CPSs characteristics include: i) have uncertainly regarding the status, readings,
and trust; ii) must achieve real-time performance requirements; iii) have input and feedback from the physical
environment without considering the communication channel; iv) include distributed management and control; v)
have systems of systems control as well as multi-scale characteristics; vi) have geographical wide-distribution for
components in locations that suffer from lack physical security.
In tele-medicine, for example, end users, i.e. doctors and patients, are connected through the internet. Thus, the high
security internet connection is required during the patients’ files/reports transfer. The control of un-/authorized flow
of information with the consideration of physical and cyber consequences is required during the design of CPSs
[14]. In addition, based on the application under concern, the communication architecture and the data must be
designed to address all requirements involved. Fig. 1 illustrates the common data flow and interactions in CPS
applications, which are also, can be applied to the MCPS.
Fig. 1 Interactions in the CPS system
In addition, it is essential to understand the physical communication channels, i.e. the physical inputs from sensors,
and the external-process channels like human operators’ reactions with the system, wherein the MCPS, medical
sensors and devices are included. For security and privacy in CPS and MCPS, high-confidence CPS and MCPS
consider the emerging infrastructure challenge. However, the traditional analysis techniques are incapable to cope
with both their complexity and predicting the system behavior. For instance, the MCPS requirements for security,
dependability, privacy and safety grow immensely with the use of the enormous number of connected medical
devices and sensors in the Internet of Things (IoT) systems during the interaction with the physical world and
humans. Thus, proper technology is required to design and to hypothesize deep interdependencies for engineering
systems. New relationships between the physical components and the cyber entail new architectural models, where
the traditional real-time performance is inadequate for spatially and large CPSs. Since in the CPS and the MCPS as
well, the feedback and input are from the physical environment, the presence of communication channels, which
require security, is not usually considered. This is one of the CPS significant specific characteristic [15].
Incorrect specification of the information flow/accessibility requirements/control and/or implementation errors in the
CPS and MCPS systems will lead to security failures. Security specification requirements should be considered for
superior network development. Sensors security is an essential step in the CPS and MCPS systems. Procedures for
tamper detection and input validation provided by the integrated sensors is significant to prevent recruited by
adversaries in the control inputs to the cyber-physical system. Hence, the security is considered a part of the
application development and system architecture. The assembly of data placement, monitoring and system control
Virtual interaction
Intelligence
Physical spaceVirtual space
Physical interaction
Dataflow
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must consider the security implications [16]. Finally, the developed MCPS architectures and the system
improvement tools are provided. Such isolation for security includes performance isolation, control isolation and
data isolation within the virtualized distributed systems.
Embedded systems achieve higher predictability and reliability standard compared to the general-purpose
computing. Thus, the integration of computing and the physical processes has a significant role, especially with the
advancement of the embedded systems. Such incorporation leads to important applications, for example, in aircraft
control systems, medical systems, weapons systems, communication systems and automotive electronics.
Nevertheless, the embedded systems can be considered closed boxes that do not interpret the computing ability. The
required fundamental transformation generated from networking the embedded devices faces several practical
challenges. Several applications require networked and feature-rich embedded systems. The real-time dominant
view has been well established before embedded computing. The current design of all operating systems,
programming languages and computers may not fit the CPS and MCPS systems. The most extensively used
networking procedures present the stochastic behavior and timing variability. Currently, the embedded systems use
networking technologies. Cyber-physical systems are synchronized with nature and their integration with computing
necessitates simultaneous composition of the computing methods with the physical ones. Embedded systems must
respond to multiple real-time sensor stimuli streams and multiple actuator control simultaneously. Unfortunately, the
interaction mechanisms with actuator hardware and sensors produces the interfere concept, which is not well
signified in programming languages. Typically, a CPS requires improved predictability and reliability to be
deployed in healthcare, automotive safety and traffic control applications [17]. Since the physical systems are not
exclusively predictable, CPSs will not operate in controlled environments and must be flexible to subsystem failures
and robust to unpredicted conditions.
In CPS and MCPS, a standard architecture can be considered in the social spaces. Cyber-physical systems
progressively operate in social spaces, such as in the smart grid, disaster response systems and transportation
systems where humans are the users, survivors or drivers. The main features of the CPSs include: functional
integration, emergent intelligence, increasing complexity and adaptive behavior/structure leading to humans’ huge
impact on the environment. In a CPS, the users can be both in--the-loop and out-of-the-loop, where these systems
have compatible characteristics [18, 19]. The IoT adopts that things exchange information and interact to provide a
foundation for future prevalent computing environments. Consequently, the CPS concept is delineated from the
Internet of Things (IoT) as illustrated in Fig.2 [20].
Fig.2. The cyber-physical systems standard architecture [20]
The CPS paradigm is still under progress; accordingly, different interpretations and implementations forms attract
the focus of the researchers. Generally, CPSs and MCPS can be considered to be physical, engineered systems
whose processes are monitored, controlled, coordinated and securely integrated by a communication and computing
core at all levels and scales. It can be considered as two sub-systems, namely: i) cyber sub-system which is
event-oriented, logic-based and discrete system that is responsible for communication, computation and control and
ii) physical sub-system, which operates continuously and integrates the human-design and natural components that
follow the physics laws. Subsequently, MCPSs have the dynamism, evolutionary and decentralization nature, where
these systems are functionally and structurally open, intelligent, context-sensitive and self-adaptive engineered
Human
interfaces
Status
monitors
Action
controllers
Effect
actuators
Ambient
sensors
Network
managers
Reasoning
engines
Sensation
converters
Information
explorers
Signal
transmitters
Big data
handlers
Service
generators
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systems at which the physical and the cyber sub-systems evolve and interact cooperatively to increasingly penetrate
into the social space as well as into the humans’ world to support healthcare.
Generally, CPSs are gradually becoming part of the social-technical society fabric instead of being only just
technical systems. They integrate the interaction between the embedded environments with the human domain
forming two consistent socialization dimensions. These systems can be considered social-technical complex
systems, wherein human and technical parts are immensely intertwined. Social-cyber-physical systems (SCPS)
operate based on the humans’ expectations, and the society/communities. These systems should have particular
elementary social capabilities, namely: synchronizing their performance, accessing the data of users, sensing users
and the social networks/associations between them, understanding the social goals based on the user model and
social context, deducing the social context based on the networks topology of the users and providing a context
driven output. The SCPS realization should encompass the social context which comprises a social person believes,
culture, attitudes and the social interactions [21]. In this context, SCPS will have extra characteristics over CPS
systems: i) the awareness ability of the users and their individuals and the social contexts, ii) can adapt themselves
towards optimal collaboration, iii) the ability to accomplish the highest possible dependability level, security,
accountability, maintainability, and accessibility and iv) the ability to attain a balance between the resources and the
outputs expenses. However, data sources may be undependable in this context that is considered a challenge for CPS
systems.
Advanced CPS applications are progressively operating in the social spaces at which the humans have a significant
part in the inclusive system. Henceforth, CPS and MCPS imminent applications will be engineered with a
consideration of the humans in the loop. The medical sensors can contribute to the patient’s records, survivors can
collect data on damage in the natural disaster cases and drivers can contribute data in the traffic blocking at various
locations. Generally, the CPS in the social space can be employed in the various healthcare applications through the
MCPS.
3. Medical Cyber-Physical System
Broadly, social media/space refers to Web-based facilities/tools that allow quick, easy and wide communication
between individuals. It has great impact in the medical and healthcare applications as well as it provides a venue for
interactive communication between the patients, physicians and health-organizations’ staff quickly. It allows the
transfer of the patients’ files and records easily [22]. This leads to appraising role of the social media in healthcare
applications. Consequently, SCPS becomes an undeniable force that has great influence on the medical sector;
especially with the evolution in the medical device industry that employs the embedded software and the networking
connectivity. With the advancement in the medical devices, it became interesting to replace the devices that
designed to treat the patients independently of each other by integrating devices using distributed systems that
concurrently control/investigate the patient’s different physiological aspects. The combination of embedded medical
devices, networking abilities and the complex physical dynamics transformed the medical system to contemporary
medical device systems that considered a class of the cyber-physical systems, which call medical CPS (MCPS) [23].
Generally, there are several trends that emerged with the use of MCPS including [24] [25] [26]:
I. Improvement networking abilities: Currently, the medical devices’ networking abilities are mainly used to
monitor the patients via local connection of different medical devices to incorporate the patient monitoring
and/or for remote monitoring as well as to interact with the electronic health records for storing.
II. New software-empowered embedded systems: Due to the new trends in the embedded systems, new
functionality is motivated by the new software possibilities that developed the medical device systems.
III. The need for automatic monitor for the patient’s status: Using an automated controller can deliver
continuous observing of the patient’s state and can handle routine situations.
IV. New inventions in the health care industry: The development in the healthcare devices, such as
bio-sensors, accelerated the implementation of cloud computing and thus the social CPS systems.
V. Development of computer technology and wireless communication: Information technology, networking
and broad mobile broadband networks, motivate the use of such portable devices to access the Internet services.
Thus, mobile healthcare becomes more popular through the CPS systems.
