medical costs in the united states have risen rapidly 
 and substantially , making health care expenditure one of 
 the most troubling economic and social problems for 
 the u.s.a . the local , state and federal governments as 
 well as citizens are generally aware of the magnitude 
 and seriousness of the problems of health care costs to 
 individuals and their families , to communities , and to 
 the nation . according to the national coalition on 
 health care ( 1 ) , the u.s.a . has the highest health care 
 expenditures compared to other industrialized nations . in fact , the u.s.a . annual health care expenditures 
 constitute a significant portion of the u.s . gross 
 domestic product ( gdp ) . for instance , health care 
 expenditures in the u.s.a . reached $ 2 trillion in 2005 
 and are projected to reach $ 4 trillion or 20% of the gdp by 2015 ( 1 ) . in addition to this health - care cost problem , 
 the numbers of elderly adults and population are 
 growing along with increased longevity and more 
 demands for different health care services resulting 
 from changes in lifestyles . according to the u.s.a . census bureau ( 2 ) , 35.9 million people were aged 65 
 and older as of july 2003 and this number is expected to 
 double within the next 25 years . by 2030 , almost 1-outof- 
 5 americans , about 72 million people , will be 65 
 years or older . worldwide , the number of adults older 
 than 65 years is also expected to increase from 420 
 million in 2000 to 974 million by 2030 . apparently , 
 there are two severe problems facing the u.s.a . health 
 care system ( and perhaps those of other developed 
 countries ) : enormous health care expenditures and the 
 large growing number of elderly adults who need 
 frequent and more health examinations and monitoring , 
 which in turn drive up the health care cost further . while the sky - rocketing health care expenditures are 
 the result of various issues such as increased and uncontrollable charges from health care providers and 
 increased cost of medicine , it is believed that 
 implementing advanced technologies for medical 
 practices and health treatments not only will help 
 reduce medical costs , but will also improve the 
 treatment for patients from medical professionals . for 
 instance , the use of advanced robotic , wireless and 
 information technologies can assist surgeons to perform 
 remote surgeries quickly , accurately and safely on 
 individuals located far away from the surgeons ( 3 ) . therefore , it is crucial that not only advanced health 
 care techniques and devices are developed and 
 deployed , but also that technologies potentially leading 
 to improvement in health care are introduced to the 
 health - care professionals and organizations . technologies , in general , and sensing , imaging , and 
 wireless communications , in particular , have advanced 
 considerably in the past decade which in turn can affect 
 not only health care costs , but can also influence health 
 examinations and monitoring . for instance , advances 
 in sensing , imaging , and wireless communications have 
 opened the door for possible wireless , fast , accurate and 
 remote monitoring , examination and diagnosis of the 
 inside of the human body . these advances have led to 
 the development of advanced medical techniques and 
 equipment such as magnetic resonance imaging ( mri ) 
 ( 4 ) and endoscopic ultrasound ( 5 ) . in order to push 
 forward medical technologies , improvement in health 
 care techniques to 
 that end , it is imperative that advances in technologies 
 be utilized wisely and properly for medical applications . one of the most significantly advanced technologies 
 in the past decade is radio - frequency identification 
 ( rfid ) , which has profound impact on various 
 applications  from consumer to military applications . rfid technology dates back to the 1940s as a military 
 technology for identifying aircraft in world war ii ( 6 ) . the recently declining cost along with improved 
 sensitivity and durability of rfid systems has made 
 these systems increasingly interesting for the 
 distribution and retail industry . in fact , rfid has been 
 identified as potential technology to replace the 
 currently dominant upc bar - code system ( 7 ) . rfid is 
 very attractive for medical applications and if properly 
 utilized can potentially lead to breakthroughs in the way 
 medical examinations and monitoring of patients are 
 conducted . in this paper , we present several ideas of using rfid 
 technology for personal health examination and 
 monitoring . our main objective is not to present 
 specific rfid systems for these medical practices , 
 which are outside the scope of our research and requires 
 significant collaborated efforts between different 
 disciplines , but to give ideas that can possibly lead to significant improvements in medical examinations and 
 monitoring of patients . it is hoped that this paper will 
 provide medical professionals and students some 
 overview of what rfid technology can potentially do 
 for medical applications , effectively motivating and 
 facilitating them to utilize this valuable technology not 
 only for the improvement of patient treatments , but also 
 to possibly develop particular rfid devices , in 
 collaboration with other disciplines such as biomedical 
 and electrical engineering , for specific medical needs . understanding the basics of rfid helps medical 
 professionals , such as medical doctors , not only to 
 properly utilize the technology for medical practices , 
 but also to possibly improve it for specific medical 
 needs . 1 shows a general rfid system consisting 
 of a tag ( or transponder derived from 
 transmitter / responder ) and a reader ( or interrogator ) . the basic objectives of a rfid system are to acquire , 
 store , process , and report specific data or information 
 about objects at an appropriate time and location , 
 determined by users or operators , via wireless means . 
 detailed information on rfid as described in this 
 section can be found in the rfid handbook by klaus 
 finkenzeller ( 8) . in operation , the tag is attached to the object to be 
 sensed , monitored , imaged , or identified . for instance , 
 tags about the size of a large grain of rice are implanted 
 under the skin of a dog , cat , or other animal for 
 identification purposes ( 9 ) . implantable tags of about 
 11 millimeters long and 1 millimeter in diameter can 
 also be placed under the skin of hands and arms in 
 humans for identification , physiological characteristics , 
 health , nationality , etc . particularly , as noted in 
 ( 8) , alzheimer s patients , mentally ill patients and 
 people with communication difficulties could benefit 
 from implanted rfid chips for identification purposes . data can be pre - programmed or written ( during 
 operation by the reader ) into the tag to provide 
 instructions for the tag to perform certain functions or identification of the object . the tag acquires and stores certain data from the object 
 for various functions such as monitoring the object s 
 activities . the tag is typically programmed so that it 
 automatically activates when it is within the 
 interrogation zone of readers . however , the tag can also 
 be activated at any time by the user or operator . the receiver includes circuits used for specific 
 functions , such as collecting temperature of the object , 
 and is used to receive , store and possibly process 
 specific information of an object onto which the tag is 
 attached ( with help of dsp ) as well as receive 
 information sent by the reader . not all tags 
 require transmitter , receiver , antenna or dsp , nor do 
 they conduct the same functions ; depending on the 
 applications , some of the components or functions are 
 not needed . for instance , in applications where only 
 data reading is needed , such as object identification , a 
 receiver is not contained in the tag . a reader may include a communication device to 
 enable the transmission of retrieved data to other 
 systems , such as a pc and/or other portable devices like 
 pda for storing , processing and display or further 
 communication with other media such as the internet , 
 from which the information can be retrieved by remote 
 offices . the dsp controls the reader , processes and 
 stores retrieved information , and provides interface with 
 other possible communication devices for transmission 
 or reception of information . all rfid functions are carried by radio waves at 
 various frequencies depending on the application . these include low frequency band from 100 - 500 khz , 
 intermediate frequency band from 10 - 15 mhz , and high 
 frequency bands from 850 - 950 mhz and 2.45 - 5.8 ghz 
 ( 8) . higher frequency 
 provides a broader choice of different types of antenna 
 ( 13 ) , which is the main component influencing the 
 overall size of the rfid system . higher frequency also 
 results in smaller antennas and hence smaller systems 
 ( 8) . in applications involving media with substantial 
 losses , such as the inside of the human body , lower 
 frequency bands may be needed to facilitate the 
 transmission and reception of signals . typical rfid 
 systems have practical read distances ranging from about 5 cm up to a few meters depending on the chosen 
 frequency and antenna ( 8) . personal health care and treatment for patients 
 depends largely on the ability to assess their health 
 condition . accurate and reliable assessment of health 
 condition is essential not only for personal health , but 
 also for the planning of health maintenance , including 
 treatment . it is , indeed , one of the most important tasks 
 in health care and preventive medicine . current 
 personal health examination and monitoring typically 
 involves data collection using devices and equipment 
 connecting to the body via wires this kind of health examination 
 and monitoring is normally carried out periodically in 
 certain durations and thus may not represent an 
 optimum or completely desirable solution for patients 
 who are constantly in need of examination and 
 monitoring , such as those having severe problems . as 
 will be seen in the following , the use of rfid allows 
 personal health examination and monitoring to be 
 wirelessly conducted either periodically or 
 continuously , which should benefit medicine 
 significantly , not only in cost reduction but also in 
 enhanced treatment of patients , as compared to what is 
 available now . 2 illustrates an idea of personal health 
 examination and monitoring using the rfid technique . it shows tags attached to the body s skin and readers 
 located externally to the body . different tags may be 
 used for different functions , such as reading the lung s 
 temperature , measuring the blood flow , measuring the 
 heart rate , etc . ) . the readers may be placed at various 
 locations  for instance , at different places in the house 
 of the person being monitored or in a medical facility . the tag performs specifically instructed functions and 
 transmits the data collected to the readers . the tags can 
 also receive instructions from the readers to perform 
 additional functions or to modify some preprogrammed 
 functions , such as changing the time or duration of the 
 data collection period . the readers transfer the received 
 data to a router , a pc or pda which is connected to the 
 internet . the pc or pda is also used to store the data 
 and can analyze and display them in a useful format , such as heart - beat waveforms , for immediate use by 
 someone such as an in - house care taker . the 
 information transmitted to the internet can be viewed by 
 different authorized remote offices such as a doctor s 
 office , an emergency facility , etc . the reader can also 
 be configured as a mobile handheld device to be 
 operated by a medical professional , such as a nurse , to 
 read the patient s tag data on his / her visit to the doctor s 
 office . information from this portable reader is 
 transmitted wirelessly to a pc for data storage , 
 processing , diagnosis and display . additional functions 
 such as data analysis and display can be built into this 
 portable reader to provide patient s information directly 
 to the medical professional without using a pc . it 
 should be noted that medical professionals from remote 
 offices can also control the readers to act upon the tags 
 through commands transmitted to the readers via the 
 internet , as needed for proper actions . another idea for personal health examination and 
 monitoring using the wireless rfid technique has tags 
 implanted onto certain body s parts and readers attached 
 to the body s skin . as described in the other idea 
 illustrated in fig . 3 , the tags perform various functions 
 on the human s parts and transmit the collected 
 information to the readers , which are connected to the 
 router , pc , or pda wirelessly . this idea requires the use 
 of implantable tags and is thus more difficult to be 
 implemented . however , it is more effective for 
 examination and monitoring because tags have direct 
 contact with the parts to be monitored and can 
 accommodate a wider range of monitoring than those 
 used in fig . wider range of 
 monitoring is possible since more implantable devices 
 can be placed at different places in the body for 
 monitoring while only a limited number of parts can be 
 monitored using tags attached to the body s skin . a 
 potential problem of this approach is the transmission of collected data from the implanted tags to the readers 
 partly or completely across the body , whose media have 
 very high loss ( 15 ) and hence attenuate substantially the 
 transmitted signals that carry the collected data . these 
 signals may thus be too weak to be detected by the 
 readers . another potential problem is the radiation 
 exposure inside the human body which might cause 
 other health issues . this potential health effect indeed 
 needs extensive study before the deployment of 
 implantable tags . this concern , however , is expected to 
 be less than that with cell phones if the radio signal 
 reaching the implantable tags is limited to much less 
 than that currently used by cell phones , which is 
 possible since the rfid range is only a fraction of what 
 is used for cell phones . implantable tags should not 
 allow radiation exposure exceeding a safe level , nor put 
 patients at further risk for other problems such as 
 infections after they are approved by an authorized 
 government health organization such as the food and 
 drug administration ( fda ) , which regulates medical 
 devices in the u.s.a . in fact , in 2004 , the fda 
 approved an rfid tag for implantation in humans as a 
 means for accessing a person s health records ( 17 ) . implantable rfid chips designed for animal tagging 
 are now being used in humans ( 10,11 ) . most 
 importantly , this approach should be used only for those 
 in dire conditions , such as patients in the situation that 
 have no other choices for monitoring purposes , due to 
 the need of patients operation and implantation . implantable tags require special materials and 
 packaging for them not to cause detrimental effects to 
 the body upon implantation . development of such tags 
 requires significant interdisciplinary collaboration 
 between different disciplines such as electrical 
 engineering , biomedical engineering , and medicine . 4 shows an application of rfid in examining and monitoring many patients simultaneously in a 
 medical facility . each patient carries tags that are either 
 attached externally to the body or implanted inside the 
 body and can be identified with a unique i d 
 preprogrammed into his / her tags . this arrangement not 
 only improves the examination and monitoring of 
 patients significantly but also substantially reduces the 
 use of the financial and personal resources , thus 
 offering a very efficient and cost - effective health 
 assessment and monitoring system . although periodic personal health inspections and 
 monitoring are important , there is a significant interest 
 and need not only to examine but also to monitor health 
 condition continuously . continuous monitoring of the 
 health of patients provides instantaneous information on 
 the state of patients , effectively and significantly 
 improving health care , especially for elderly patients or 
 those experiencing deteriorating health . this can 
 effectively help medical professionals to respond 
 quickly and more efficiently in emergencies , helping 
 prevent many potentially catastrophic events . additionally , continuous monitoring supplies valuable , 
 complete and accurate health condition of the patients . this information will allow medical professionals to 
 conduct long - term studies of the patients health 
 condition and gain invaluable knowledge not only of 
 the patients but also of particular illnesses . the 
 information can also make feasible more accurate 
 prediction of the patients future health conditions  
 thus allowing optimum treatment plans to be made . continuous monitoring of personal health conditions 
 wirelessly from a remote location further offers more 
 convenience , lower cost and facilitates improved care 
 for patients , particularly out - patients or those living in 
 rural areas that are inconvenient and difficult to access 
 to health care facilities , or in emergency situations . it 
 should be particularly noted that the constant 
 monitoring of patient well - being does not take into 
 account the non - measurable aspects such as pain , but 
 the use of the proposed rfid techniques should not 
 duplicate the function of a nurse working with the patient for pain . as with any technology and its intended applications , 
 the cost of the proposed rfid systems can be 
 approximately broken down into two categories : rfid 
 system development cost and implementation cost . for 
 system development cost , existing tags and readers 
 developed for consumer applications consumer tags and 
 readers are relatively inexpensive - a tag can cost as low 
 as a few u.s . cents ( 18 ) and a reader can cost around 
 100 u.s . dollars ( 19 ) . specially designed implantable tags are needed in 
 one of our proposed ideas and , for these tags , new 
 research and development needs to be conducted . we 
 expect that the cost of these implantable tags , once fully 
 developed and mass produced , should be very similar to 
 that of the existing tags . the primary cost of developing 
 the proposed rfid systems lies in the integration and 
 testing of the rfid systems for the particular 
 application of personal health examination and 
 monitoring . all these development costs , however , are 
 born by biomedical - equipment development companies 
 just as in the development of any other medical 
 equipment . this cost mainly 
 consists of the cost for purchasing readers and tags , cost 
 of maintenance and for the rfid sensor networks to be 
 installed in medical facilities as proposed in fig . the prices 
 of the readers and tags , as discussed earlier , are 
 inexpensive . the rfid system is basically a wireless 
 device and its maintenance is also relatively 
 inexpensive . the installation cost for rfid sensors in 
 a medical facility is very similar to the installation of 
 other in - building wireless networks such as wi - fi 
 hotspots for internet access ( 20 ) . nevertheless , presently , the 
 actual cost for implementing the proposed rfid sensor 
 network is not available , as this system is new and has 
 not been implemented for medical practices . a major concern with the use of rfid technology in 
 the medical field is its ethical aspects . for instance , it may be possible to gather 
 sensitive data about a patient without consent through 
 reading of the tags at a distance without his or her 
 knowledge . furthermore , tags can be used for nonconsent 
 surveillance of the patient or other purposes . additionally , patient data transmitted through air or the 
 internet can also possibly be stolen without consent . these privacy issues , however , may be completely or 
 partially resolved with proper encryption methods . in 
 general , the ethical concerns can possibly be addressed 
 with better and more secured technologies for rfid . we have presented several ideas using rfid 
 technology , one of the most significantly developed and 
 advanced technologies in the past decade , for personal 
 health examination and monitoring . these ideas 
 demonstrate that health examination and monitoring of 
 patients can be done wirelessly at any time and any 
 place without interfering with the patients normal 
 activities and should therefore be attractive once 
 developed and deployed for the medical field . it is 
 believed that implementing the rfid technology would 
 not only help reduce the enormous and significantly 
 growing medical costs in the u.s.a . , but also help 
 improve the health treatment capability as well as 
 enhance the understanding of long - term personal health 
 and illness . it is hoped that these ideas will serve as a 
 way to illustrate potential use and advantages of the 
 rfid technology for medical applications . potential 
 applications and advantages of the rfid as well as 
 other advanced electronic technologies for medicine are 
 enormous and if properly developed and implemented , 
 can have tremendous impacts on the medical field . in 
 essence , they allow us to  see farther , wider and 
 clearer  into patients bodies , which is one of the 
 ultimate objectives of medical professionals and most 
 desirable capabilities in medical treatments . applications of these technologies to medicine seem to 
 be limited only by our imagination  with creativity , 
 numerous applications of these technologies in the 
 medical field can be derived .
this paper presents several possible applications of the radio - frequency identification 
 ( rfid ) technology for personal health examination and monitoring . 
 one application involves using 
 rfid sensors external to the human body , while another one uses both internal and external rfid 
 sensors . 
 another application involves simultaneous assessment and monitoring of many patients in a 
 hospital setting using networks of rfid sensors . all the assessment and monitoring 
 are done wirelessly , 
 either continuously or periodically in any interval , in which the sensors collect information on human 
 parts such as the lungs or heart and transmit this information to a router , pc or pda device connected 
 to the internet , from which patient s condition can be diagnosed and viewed by authorized medical 
 professionals in remote locations . 
 instantaneous information allows medical professionals to intervene 
 properly and in a timely fashion to prevent possible catastrophic effects to patients . 
 the continuously 
 assessed and monitored information provides medical professionals with more complete and long - term 
 studies of patients . 
 the proposed ideas promise to result in not only enhancement of the health 
 treatment quality but also in significant reduction of medical expenditure .