2017
ABSTRACT
In the passed several decades, implants medical device has been highly developed and applied on patient monitor and treatment.(Ferguson & Redish, 2011) An implant medical devices(IMDs) is an connected man-made device which is helpful on patients’ treatment by implanted semi-permanently or permanently in human bodies.(Joung 2013) It is usually made of a biomedical material such as silicone and may contain electronics.(‘Implant’ 2005) Connecting IMDs provide remote monitoring services to collect a considerable amount of data from patients and they can place treatments in human bodies. (‘Implant’ 2005) The wire IMDs are commonly used at present; however because these wires must cross the skin, this is at risk of being pull out and bacterial infection.(Ferguson & Redish, 2011) As an alternative, wireless technologies could bring many benefits and may replace the wires in the future. This paper will introduce many details of IMDs and list the benefits of connecting IMDs. In addition, some challenges and issues associated with wireless IMDs will be discussed in this article.
Keywords: implants devices, wireless, medical monitoring
CONTENT
1 INTRODUCTION 4
2 LITERATURE REVIEW 4
2.1 Functional classification 4
2.2.1 Cardiac implant devices 5
2.1.2 Neurostimulation 5
2.1.3 Drug delivery system 6
2.1.4 Biosensors 6
2.2 Developments 7
2.2.1 Intrabody Communication 7
2.1.2 Pseudo-IMDs 8
3 BENEFITS 8
3.1. Monitoring 9
3.2 Lower cost and more efficient 9
3.3 Research approvement 10
4. IMPLANTS COMMUNICATION SYSTEM 10
4.1 Pacemaker with wireless connection 10
4.2 Neurostimulation production 10
5 CHALLENGES 11
5.1 Coverage area 11
5.2 Frequency allocation 12
5.3 Data transmit challenges 12
6 ISSUES 13
6.1 Power issues 13
6.2 Security issues 14
7 SUMMARY 15
BIBLIOGRAPHY 17
1 INTRODUCTION
A lot of people die due to the issue with chronic and lately diagnosed diseases in each year, such as cancer, obesity, asthma. (Akbar & Cang 2016) The target of the medical implant devices is to increase advanced signal obtaining and to improve signal processing. (Zhang, Bhide & Alvandpour 2012) To achieve the target, Implant medical devices monitor physiologically, Common medical implant devices include implantable cardiac defibrillators and pacemakers.(Zhang, Bhide & Alvandpour 2012)
The number of IMDs is increasing at an incredible speed in world wide and most of medical areas have been covered, such as sensory and neurological, cardiovascular, orthopedic, contraception, cosmetic.(‘Implant’ 2005)
To achieve communication with IMDS, wireless radio frequency or wired would be used. (Mosesov & Mill 2007) Furthermore, as an alternative method for wireless communication, intrabody communication transfer signals by conductive properties.(Ferguson & Redish, 2011)
2 LITERATURE REVIEW
2.1 Functional classification
Based on the different functions, IMDs can be grouped by their functions: Cardiac implant devices, neurostimulators, drug delivery system, biosensors. (‘Implant’ 2005)
2.2.1 Cardiac implant devices
This kind of implant devices, such as pacemaker, are designed to support heart disease treatment by monitor the electrical activity of heart and to guarantee the heart pump at desired speed. The first pacemaker was invented in 1950 and this initial device was consisted with vacuum valve technique. (Holzer 2003)This first version pacemaker is not available until 1956. The first human usable pacemaker was inserted in 1958, but this devices shut down after three hours and a new one was implanted after few day into the same patient. (Holzer 2003)In the 1970s, cardiac implant devices began to be largely produced because of demand. Since then, the revolution speed of cardiac implant devices became incredible. (Holzer 2003)In recent years, communication system has been considered to be inserted into cardiac implant devices such as pacemaker. (Holzer 2003)
2.1.2 Neurostimulation
These devices are implanted in different areas, depending on the requirement of patient’s condition, to transmit electrical signals in brain. (Holzer 2003) The process, commonly called Deep Brain Stimulation (DBS), has been applied to treat many neural disease such as Parkinson, dystonia. This technique has been using for 50 years. However, it is becoming widely apply until recent years because of new invention in this area and more possible potential treatments are released. (Holzer 2003) Neurostimulation was not quite popular and was replaced by another stimulation which is spinal cord stimulation. Stimulation was first applied on brain in 1874 and became famous in the 1970s as an effective treatment for Parkinson disease. Nevertheless, this popular did not keep for a long time because of its disadvantage. (Cruccu et al. 2007)
2.1.3 Drug delivery system
Drug delivery system (DDS) is usually implanted under the skin and consists of a pump. The function of DDS is provide a specific way to supply drugs and deliver medication to the target area directly. (Holzer 2003)Because of these feature, treatment could be more efficient and less painful. The first drug delivery system was began in 1952 for sustainable release formulation. Between 1950 and 1980, the first generation drug delivery primarily for oral and transdermal release system. (Holzer 2003)Many new aims was shown in the 2nd generation devices in the period from 1980 to 2010, including “zero-order release system” and “self-regulated drug delivery system”. In the second generation of this system, the Journal of Controlled Release (JCR) playing an irreplaceable role and will continue contribute as an important component of the next generation drug delivery technology. (Park 2014)
2.1.4 Biosensors
The application is implant a sensor or a set of sensor into human’s body to collect patient’s health parameters and make decision depend on these collection. (Holzer 2003) After many years development, this medical devices are main used as a control node and connected with other sensor as a component of sensor network,this network could supply data to contribute to decision making. The biosensors was first mentioned in 1906, but its conception was first introduced until 1909. (Holzer 2003) The first real biosensor was made in 1956 for oxygen detection, then I=in 1975, biosensors began to be developed for commercial purpose. (Holzer 2003)After the development of i-STAT sensor, more and more remarkable achievement has be reached. With the development of micro and nanotechnology, biosensor becoming more important in medical field.(Bhalla, Jolly & Estrela 2016)
2.2 Developments
2.2.1 Intrabody Communication
Intrabody communication is a new type of technology used on medical devices implant . It could be divided into to class: capacitive intrabody communication and galvanic intrabody communication.(Ferguson & Redish, 2011)
The first Intrabody communication, which is called capacitive intrabody communication, was first reported in 1995 by Zimmerman et al. (Velliste et al. 2008). Since then, intrabody communication has attracted tremendous attention, as a new developed implant medical devices technology. It is a alternative wireless communication method which use body properties to transmit signals. This technology has been applied for transmitting data to medical devices.
Handa et at. stated the second type of intrabody communication, galvanic, in 1997.(Handa et al. 1997) In this system, the transmitting and receiving are contacted with skin directly, lead to galvanic coupling. It is noticeable that this communication system only demand small power support(8 µW). Because of its no connection, this telemetry has been used on implanted medical device.
Many researches related with intrabody communication are still ongoing at present. In the future, this technology could be used on solving telemetry and power issues of connected implant medical devices.
2.1.2 Pseudo-IMDs
Implantable medical devices are mainly divided into long-term IMDs and short-term IMDs. Pseudo-IMDs is a type of short-term IMDs, which stay only few hours or days inside human body. (Joung 2013) For instance, there is a kind of pacemaker stay in patient’s body for 7 days to help them to control their heart rate. After 7 days, this pacemaker would be removed and patient can enjoy their regular life again.(Joung 2013)
3 BENEFITS
Connecting implantable medical devices has been researching for many years. As a new generation of implant medical devices, connected IMDs has networking function and much more complex calculate capability. This revolution could provide many incredible benefit. This chapter will discuss few of these benefits associated with connected IMDs.
3.1. Monitoring
These implant medical devices which are equipped with communication system can help doctor to monitor patient’s condition and to make reaction in case some incident happen. (Goldman 2006) For example, blood sugar levels, drug doses, blood pressure can be tracked so that patients manage their meeting with doctor. This benefit is supported by the data measuring function.(Goldman 2006) Since many implantable device could transmit data to outside body devices, it is much easier to constantly monitor patient’s real-time condition without surgery.(Goldman 2006)
3.2 Lower cost and more efficient
Recently research show that over USD 1800 was cost daily in the US in 2014. This means a large number of human resources are required and lots of unnecessary capital was waste. For connected medical devices, as the treatment could be done more specific than traditional medical devices, the cost would be decreased both for patient and hospital.(Goldman 2006) For instance, a drug delivery device which equipped with communication system could provide drugs automatically at the right time. This decrease the possibility of ruining out of life-support medication and improve the efficiency of the usage of drug. (Goldman 2006)
3.3 Research approvement
As connected implant medical devices have the ability to measure parameters of patient’s body and collect data, more valuable data is available for researchers and be analyzed. Bese on current cloud computing and Big Data analysis, the efficiency of treatment could be improved and new medical techniques would be developed.(Goldman 2006)
4. IMPLANTS COMMUNICATION SYSTEM
4.1 Pacemaker with wireless connection
There are some implantable medical devices has been produced with wireless or wire communication system. In 2001, a pacemaker with remote control and monitoring function was achieved. This transmitter which is named CardioMessenger has the ability to transmit data with implanted devices within 2m. By using GSM network, data collected from patients is send to a centre and be analyzed.(Burri 2009) This system is suitable for most GSM network which means patients could continue to be monitored even in abroad. Furthermore, this pacemaker has a rechargeable battery, that extend the lifecycle of this pacemaker.(Burri 2009)
4.2 Neurostimulation production
BlueWind Medical’s Vivendi is a kind of neurostimulation which is smaller than most of existing neurostimulators and could be wirelessly recharged. Patients themselves can control the devices easily at home and reduce painful result from peripheral neuropathic pain (PHP). (Deer et al. 2014)
5 CHALLENGES
Connected implant medical devices could contribute many benefits. However, several challenges are confront of connecting medical devices, especially for wireless IMDs. (Cypher et al. 2006)This section will consider many challenges such as coverage range, output power and frequency allocation. As wireless medical devices have many advantage over wired, such as reduce risk of infection and failure and less invasion, it is necessary to overcome these challenges.
5.1 Coverage area
There are four main coverage area which are body area, personal area, local area and wide area. In body area, human body is able to reduce the intensity of signal and cause low data rate. Wireless body area network standards could be applied to against this challenge, as it is using electromagnetic wave, which is easily for data to transmit through body. (Cypher et al. 2006)This problem can not be addressed by wireless personal area network (WPAN) standards which are very closely to WBAN, because these standards do not cover implant community. 802.15 family can satisfy the requirement of personal area whereas 802.11 is designed for the local area. (Cypher et al. 2006)Because of the using of frequency and the physical environment, coverage range usually changes widely. This is an advantage for personal area, since limited cover area is demanded by personal area signal.(Cypher et al. 2006)
5.2 Frequency allocation
Wide range is covered by the radio frequency spectrum, from 3kHz to 300 GHz. However, the allocation of RF is not controlled by the medical environment’s management. (Cypher et al. 2006)Although, in these range, several bands are available for medical usage, they are also accessible by other users. Using which band is the mainly consideration. The 2400 MHz industry, Scientific, Medical (ISM) is selected by many wireless technologies, such as 802.11b and 802.15.1. If overcrowd occur in the 2400 MHz band, IEEE 802.11a and IEEE 802.15.4 are considered as other bands are available.(Cypher et al. 2006)
After bands are choose, another challenges should be concern is the interference. As one of the feature of wireless technology, a device can connect and disconnect with internet at anytime and anywhere. This unpredictable arise the challenge of wireless network configuration.
(Cypher et al. 2006)
5.3 Data transmit challenges
Data transmit is the most important function for connected implant medical devices. However, there are many main limitation on data transmit, which transmit speed, available range and interference.(Islam 2016)
In fact, the data transmit range of implantable devices are usually very short, must not exceed 6cm; therefore, the controller outside the body should be kept close to or in contact with patient. (Islam 2016)Another data transmit limitation is the data rate.At real application of connected implantable devices, the data rate is very low, about 100kbps. Sometimes, patients are required to stay in a specific position to keep the transmit data rate stable. Moreover, the communication system could be affected by other communication system in the same frequency band.(Islam 2016)
To solve these problems, a general RF band, whose core band is 402-405MHz, has been suggested for connectable implant medical devices, this band has many advantages inside body, which are good conductivity, a reliable data rate, and a up to 2m communication range.(Islam 2016)
6 ISSUES
6.1 Power issues
Power supply is one of the most difficult challenges need to be overcome. Batteries are the most common method of power supply for many implant medical devices, such pacemaker and deep brain stimulation devices. (Mosesov & Mill 2007)Nevertheless, this kind of power supply has many limitations, one of them is the difficulty of miniature. This is caused by the lifetime requirement of batteries. Furthermore, recharge for batteries could be another challenge. Battery replacement for implantable medical devices would be costly and inefficient and could increase the possibility of infection.(Mosesov & Mill 2007)
Feasible recharge approach has been found, such as radio frequency (RF) method. However, RF approaches is inefficient and demand large antennas. More researches about wireless recharge are required to make implant medical devices more practical than present.(Mosesov & Mill 2007)
In fact, a new wireless power method has been suggested which is a non-RF method called witricity.(Mosesov & Mill 2007) This method using magnetic resonance coupling theory, could have efficient energy transfer while large coils; However, this method is only in the beginning stage as many problem have not be addressed, such as low power delivery, and still require a long term to become practical. Although some other methods including optical energy and energy scavenging are researched, it is hard to totally rely on these methods at present.(Mosesov & Mill 2007)
6.2 Security issues
Some of medical devices have the ability to transmit patient’s health information to computer and even can be remotely controlled. This has arise the concern of many security issues: for instance, human error may result in wrong operations of medical devices and even power of the device. Because of the requirement of minimum size, implant medical device usually do not have enough memory to supply security function, such as firewall.(‘Medical device’ 2005) Many researches have been done to prove that pacemaker and defibrillators can be hacked and shut down wirelessly, because of the vulnerable communication channel. These researchers also state that implant medical device even could be reprogramed by hacker and lead to death. (‘Medical device’ 2005)
Another important challenge is to patch and upgrade the software inside these medical devices. As these medical devices are implanted into patient’s body, it is only possible to patch and upgrade system through wireless connection. (‘Medical device’ 2005)This could lead to the devices out of work and hard to be repaired. However, this process has to be made to against virus and fix bugs.
In addition to security issue of access, body’s response to implant is an mainly challenge need to be solve. (‘Medical device’ 2005)This response could occurs both on short term and long term. It may negatively affect the capability of the implant devices and, more importantly, the function of health system. Meanwhile, localized heating resulted from RF telemetry is another safety issue should be concern. In regard of this, low-frequency wave is proposed to avoid this issue.(‘Medical device’ 2005)
7 SUMMARY
After the first implantable medical devices was innovated, this technology has go through many major revolution. The development of many micro technology contribute to minimum the scale of IMDs and make IMDs much easier to be carrying. Because of the development of batteries, it is possible for implantable medical devices to get long-term power support with highly reliability. Short range wireless recharge technique has been advanced to extend the lifetime of IMDs and continue appealing researcher’s attention. The wireless communication system has been applied on clinical treatment with remote monitoring and control. (Goldman 2006)This contribute many benefits to medical area both for patients and doctors. Meanwhile, many solution has been suggested to address challenges associated with connected IMDs. Further research and development are demanded to solve issues such as security issues and power supply issues.
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