Elektrotechnik & Informationstechnik (2013) 130/7: 191–200. DOI 10.1007/s00502-013-0156-y ORIGINALARBEITEN
Smart NFC-sensors for healthcareapplications and further developmenttrendsS. Cecil, M. Bammer, G. Schmid OVE, K. Lamedschwandner OVE, A. Oberleitner
A promising approach for the application of NFC in healthcare is the combination of the simple handling of NFC with differentsensor functionalities. By an advanced design of the NFC-antenna and the surrounding hard- and software, the intelligent NFC-tagcan operate as a smart sensor with NFC-interface for the transfer of measurement data. According to this principle, various sensorapplications for health care scenarios can be realized. In this article several developments of NFC-sensor applications are introducedlike NFC-based fill level measurement, NFC-based analog scale (position detection), NFC-based blood-glucose meter, NFC-based cryo-sensor for vials and NFC-based ultraviolet (UV) assessment for sun burn prevention. The main advantages of these applications arethat all NFC-sensors can simply be used by medical, nursing staff or patients and consumers.
Keywords: near field communication; smart sensors; healthcare; ambient assisted living; NFC-smartphone
Intelligente NFC-Sensoren für den Gesundheits-/Pflegebereich und weitere Entwicklungstrends.
Großes Potenzial für NFC-Anwendungen im Gesundheitsbereich besteht vor allem durch die intuitive Handhabung von NFC in Verbin-dung mit verschiedenen Sensoren. Mit einem entsprechenden Design von NFC-Antenne und zugehöriger Hard- und Software könnenintelligente NFC-Sensoren entwickelt werden, deren Messdaten über die NFC-Schnittstelle zu anderen elektronischen Geräten (z. B.einem Smartphone) übertragen werden können. Nach diesem Grundprinzip sind verschiedenste Sensoranwendungen für den Gesund-heitsbereich möglich. In diesem Artikel werden mehrere verschiedene NFC-Sensoranwendungen für den Gesundheitsbereich vorge-stellt: NFC-basierte Füllstandmessung, Positionserkennung (lineare Schmerzskala) mittels NFC-Antenne, ein NFC-Blutzuckermessgerät,ein NFC-Sensor für die Kontrolle der Kühlkette von Ampullen und ein UV-Sensor zur Sonnenbrandvorbeugung. Der wesentliche Vorteildieser Entwicklungen ist die einfache Anwendung durch medizinisches und pflegerisches Personal, Patienten und Konsumenten.
Schlüsselwörter: Nahfeldkommunikation (NFC); intelligente Sensoren; Gesundheits- und Pflegebereich; NFC-Smartphone
1. IntroductionNear Field Communication (NFC) is one of the most promising wire-less communication technologies for future applications in the fieldsof healthcare, ambient assisted living (AAL), payment, ticketing, re-tail support, marketing and entertainment. NFC will be integrated inmost mobile phones and other personal communication and elec-tronic equipment in the near future, so that the spread of thisemerging technology will rapidly increase, offering a wide varietyof applications in the above mentioned areas.
The paper focuses on intelligent antenna design with additionalfunctions and smart sensor development for medical devices as wellas wireless applications. New developments of next generation NFCsensors with integrated sensor and measurement functionality aswell as applications in the ambient assisted living (AAL) and health-care sector are described and discussed.
Why do we think that NFC is best suited for AAL and healthcareapplications?
The answer is quite simple, because NFC technology is very easyto use! Just touch a NFC enabled smart card to start an applicationvia an e.g. App on a smartphone and then follow the visual or au-dio guide by just touching other NFC enabled devices and informa-tion or symbol tags. A further important advantage of NFC is that,for most applications, only one communication point or NFC en-
abled device has to be active. Therefore, NFC covers a lot of furtheraspects like energy harvesting, green technology, ultra-low radia-tion, smart integration and makes a lot of new applications readyfor the mass market [1]. Finally, with NFC the Internet of thingscan be realized quite easily. Last but not least, NFC is an Austrianinvention by NXP (formerly Philips Gratkorn) in cooperation withSony.
RFID and NFC are two closely related wireless communicationtechnologies that are used globally for a vast number of applicationssuch as access control, asset tracking and contactless payments.RFID enables a one way wireless communication, typically betweenan unpowered RFID tag and a powered RFID reader. Powered tagscan be used for applications with high distances between reader andtag (e.g. container identification). RFID-transponder without embed-ded energy supply use three frequencies: 125 kHz (LF), 13.56 MHz
Cecil, Stefan, Seibersdorf Labor GmbH, Business Unit EMC&Optics, 2444 Seibersdorf,Austria (E-mail: [email protected]); Bammer, Manfred, AITAustrian Institute of Technology GmbH, Department Health & Environment, Business UnitBiomedical Systems, 2700 Wiener Neustadt, Austria; Schmid, Gernot, Seibersdorf LaborGmbH, Business Unit EMC&Optics, 2444 Seibersdorf, Austria; Lamedschwandner, Kurt,Seibersdorf Labor GmbH, Business Unit EMC&Optics, 2444 Seibersdorf, Austria;Oberleitner, Andreas, AIT Austrian Institute of Technology GmbH, Department Health &Environment, Business Unit Biomedical Systems, 2700 Wiener Neustadt, Austria
ORIGINALARBEITEN S. Cecil et al. Smart NFC-sensors for healthcare applications and further development
(HF) and 840–960 MHz (UHF). At favorable terms UHF-transpondercan communicate over 100 m, typical distances for a steady trans-mission are 7–10 m. Because of physical limitations the commu-nication with HF and LF is restricted with maximal 2 m, depend-ing on the antenna design and the transmission power. The com-munication with NFC-devices at HF is limited at some centime-ters.
NFC operates at 13.56 MHz and is an extension of High Frequency(HF) RFID standards. NFC therefore shares many physical proper-ties with RFID especially the one way communication (reader/writer-mode). There are however three key differences:
– NFC is capable of a two way communication and can thereforebe used for more complex interactions such as card emulationand peer-to-peer (P2P) sharing.
– NFC is limited to communication at close proximity, typically 5 cmor less.
– Because of limitations in the operating systems, NFC-smartphonesusually read only one tag at one time.
A description of further possibilities and the detailed functioningof NFC can be found in [2] and [3].
These properties were developed primarily to enable secure mo-bile payments and NFC is for this reason limited to singular andclose proximity interactions. An important by-product is that NFCis now available in the majority of mobile phones and this is per-haps the most important difference between NFC and RFID technol-ogy.
The developments and prototypes introduced in this article willbenefit from the advantages of NFC communication and the wideuse of NFC enabled smartphones and some NFC enabled featurephones. The smartphones used in the described applications areused in reader/writer-mode, the passive part is an intelligent sen-sor for several medical applications with a NFC-interface. The mainadvantage in comparison to the peer-to-peer-mode is, that the sen-sor needs no energy supply, reduced NFC-capabilities and can bekept small, simple and cheap.
The basic technical principle of the data transfer from a tag toa reader with NFC is shown in Fig. 1. The connection is basicallyestablished by an inductive coupling of two antenna coils (self-inductances L1 and L2) and the coupling strength is representedby the coupling factor k depending on the self inductances L1 andL2 and the mutual inductance M between the two coils as follows:
k = M√L1 * L2
The mutual inductance is very sensitive to the distance between thetwo coils, so NFC will only work when the coils are in close proximity.Moreover, the resonance frequency of the receiver and the transmit-
Fig. 1. The working principle of a connection between a NFC-trans-mitter (NFC-reader, NFC-smartphone) and a NFC-receiver (NFC-tag orNFC-sensor)
ter coils need be tuned to the transmission frequency of 13.56 MHzin order to enable sufficient power transfer to the purely passivetransponder circuit. This can be done by a parallel capacitor. Thedata transmission from the passive transponder to the reader deviceis based on the so called principle of “load modulation”. This meansthat the transponder circuit digitally modulates the load impedanceof the transponder antenna depending on the information bits tobe sent. In Fig. 1 this is simplified illustrated by the switch S. By clos-ing and opening the switch S the load impedance of the transpon-der coil is modulated between R (switch S open) and (R ‖ Rmod).Due to the mutual coupling of the reader and transponder anten-nas this change in load impedance can be detected by the readerantenna.
2. NFC-based fill level measurementSelf-injection technologies have been growing continuously sincethe 1980‘s in many fields of medicine. They enable many patientswith chronic diseases a convenient self-treatment. Although pensand auto-injectors for administering insulin for diabetes patients arecurrently the most known and widest used products, many otherdiseases are treated using self-injection devices too, e.g. psoriasis,cancer, osteoporosis, multiple sclerosis as well as treatment of im-paired growth. Usually, such a pen consists of a dosing and in-jections mechanics in the upper part and a holder for a replace-able cartridge (“injectable”) which contains the drug to be injected(Fig. 2).
Due to cost reasons, most pens and auto-injectors are purelymechanical, i.e. they do not contain any electronics, which conse-quently means that recording about the administered dosage needsto be done manually by the patient, based on a paper/pencil prin-ciple (diary). Moreover, the remaining fill level of the cartridge canonly be obtained by visual inspection of the rather coarse and im-precise scale on the pen (Fig. 2) or by calculating from the di-ary recordings. Especially in case of elderly, mentally and/or visu-ally impaired patients, irregularities (e.g. forgotten entries) in the di-ary recordings can therefore lead to problems with dosing whichcan have serious health impacts. Therefore, a cost efficient andreliable system for the determination of the cartridge fill level ishighly desirable. The trend to disposable pens is worldwide veryhigh, so that the requirements for a cheap housing including afill level measurement system are even higher than for reusablepens.
NFC as a highly intuitive, modern and reliable short range com-munication technology in combination with a passive capacitive filllevel sensor system, was found to be a very promising approachto address the above mentioned requirements, as described as fol-lows.
For capacitive sensing of the fill level, the cartridge requires metal-lic electrodes at its outer surface which can easily be realized by avapour deposit, printing process or a label (Fig. 3).
By inserting the cartridge into the pen, the electrodes are con-nected to a sensor circuit consisting of two loop antennas (one mea-
Fig. 2. Example of a typical pen with a replaceable insulin cartridgefor diabetes treatment
S. Cecil et al. Smart NFC-sensors for healthcare applications and further development ORIGINALARBEITEN
Fig. 3. Schematic model of a pen with the passive NFC-based fill levelsensor
surement and one reference antenna) tightly packed on top of eachother, covering the same area.
In addition, a resonant 13.56 MHz communication antenna ispacked on top of the measurement and reference antenna andconnected to an advanced low power NFC-compatible transpon-der chip (currently under development), containing, in addition tothe RF-interface and CPU, two 13.56 MHz analog signal inputs, andA/D converters for processing the voltages induced in the measure-ment and reference antenna (Figs. 3, 4). The supply power of theentire transponder electronics and sensor circuit can be harvestedfrom the 13.56 MHz magnetic field of the reader device, i.e. aNFC-enabled smartphone with a corresponding software applica-tion (Fig. 5).
All the electronics required in the transponder can be operatedpurely passive (i.e., no battery inside the pen is required) and canbe realized at low cost in a size that can easily be integrated in theshaft of the pen without significantly altering its dimensions and/ordesign.
The described innovative system provides highly beneficial fea-tures for patients using self-injection systems. Beside precise car-tridge fill level measurements up to 0.5 insulin units (IU), automateddosage recordings, dosage calculators, reminder functions and di-rect wireless data transfer to health telemonitoring systems are onlya few examples of possible future applications enabled by this inno-vation.
3. NFC-based analog scale (e.g. pain scale)Visual analog scales (VAS) are frequently used to capture subjec-tive data in health status questionnaires, during psychological test-
Fig. 5. Fill level measurement of an insulin cartridge in a self-injec-tion pen by a NFC-enabled smartphone using the newly developedsystem
ing and many more application areas. The VAS usually consists of asolid line of defined length, with a verbal description of the extremestates associated to each end of the line, and the patient has to ratethe requested parameter (e.g., the perceived pain) by indicating thecorresponding position along this line (Fig. 6). In most cases VASsare still used on a paper-pencil basis, requiring wasteful (manual)post-processing and at the same time being susceptible to errors.Moreover, the fact that the VAS does not provide any feedback tothe patient is often reported to lead to difficulties of adequately as-sociating the perceived status to the corresponding position alongthe VAS.
In addition, modern Ambient Assisted Living (AAL) environmentsin general require more capabilities in terms of data acquisition anddata processing than offered by classical VASs, especially in viewof periodically assessed health relevant parameters. The applicationof NFC technology for quick, interactively and reliably capturingsubjective health relevant data can provide these needed capabili-ties.
The principle of the newly developed NFC-based interactive linearanalog scale is based on the functional extension of a passive ISO/IEC14443 compatible transponder by a sensor coil, a compensation coiland a low power analog to digital (A/D) converter (Fig. 7, see [4]).
The function is based on the sensor coil consisting of severalturns, non-equally distributed along the axis (x) of the scale. Withan increasing area for voltage induction or an increasing density
ORIGINALARBEITEN S. Cecil et al. Smart NFC-sensors for healthcare applications and further development
Fig. 6. Example of a typical visual analog scale currently used for pain self-assessment
Fig. 7. Schematic outline of the basic components of the NFC-based interactive linear analog scale [4]
Fig. 8. Example use case of the NFC-based interactive linear analogscale as pain scale
of turns from left to right the induced voltage sensor coil in-creases. The output voltage Us of the sensor coil depends on theposition (along axis x) of the peak of the highly localized mag-netic field caused by the interrogator, i.e. the NFC-enabled mobilephone.
The compensation coil consists of at least one single turn alongthe outer boundaries of the sensor coil and provides the compen-sation voltage Uc (also induced by the interrogator field), requiredto compensate for variations of the interrogator’s magnetic fieldstrength. Due to different interrogator models or varying distances(in z direction) between the interrogator and the NFC-based inter-active linear analog scale, the compensation coil is necessary. Thetwo voltages Us and Uc are A/D converted and from the relation be-tween the voltages Us and Uc the position of the interrogator devicealong the axis can be derived. The information about the current po-sition of the interrogator device is then forwarded to the memory ofthe transponder chip and repeatedly read out by the interrogator
via the transmit/receive coil using the NFC-based transmission pro-tocol.
Using an appropriate and sophisticated software application onthe mobile phone (e.g. an App on a smartphone) enables graphi-cal feedback and additional support for the user during the decisionprocess and thereby overcomes some of the problems known fromclassical visual analog scales, mentioned in the above section. Fig-ure 8 illustrates the usage of the NFC-based interactive linear ana-log scale. The user simply has to bring the mobile phone in closeproximity and slide it along the axis of the scale. The display of themobile phone provides real time feedback about the current posi-tion. When the position of the mobile phone, i.e. the reading onthe mobile phone’s display, corresponds to the value the user asso-ciates with the parameter under consideration (e.g. well-being, pain,etc.) this value will be recorded after confirmation by the user. Oncestored on the mobile phone, further processing and/or forwardingof these data via the Internet is possible in an almost unlimited man-ner.
The NFC-based interactive linear analog scale can be realized bya multilayer printing process on a foil or a label with thicknessesnot more than approximately 0.3 mm and can therefore be easilyintegrated into paper questionnaires or realized as an adhesive label.Moreover, an integration of the developed NFC-based interactivelinear analog scale into textiles is currently under investigation.
The electronic and interactive version of a visual analog scaleenables an easy-to-use, comfortable and robust way of captur-ing and quantifying subjective health relevant parameters, such aspain, pain-profiles, well-being and other parameters which oftenshould be rated in practice. At the same time overcoming severaldrawbacks of classical visual analog scales on paper-pencil bases,the actual time-stamp will be automatically recorded via the mo-bile phone. Taking into account the forecasted penetration of NFC-enabled mobile phones on the market in the near future, the de-veloped device enables patients to rate many subjective health pa-rameters anywhere, at any time, by just placing the mobile phone
S. Cecil et al. Smart NFC-sensors for healthcare applications and further development ORIGINALARBEITEN
at the corresponding position above the developed NFC-based in-teractive linear analog scale. Real time feedback about the currentposition on the mobile phone’s display and graphical support ofthe user during the decision process ensures accurate data captur-ing, and the acquired data can easily be forwarded wirelessly to atelemonitoring, therapy and compliance management center. Espe-cially for home-monitoring of patients with chronic pain, this pas-sive NFC analog scale will be a big improvement for monitoringthe efficacy of different pain therapy methods and pain medica-tions.
4. NFC-based blood-glucose meterThe daily measurement of the level of glucose in the blood is es-sential for patients with diabetes, especially patients with diabetestype 1 need to measure their blood glucose level several times aday. An easy and efficient handling of the glucose measurement iscrucial for the patients to avoid derogation of everyday life. A reduc-tion of the size of blood-glucose meters as well as a better graphicaluser interface for better usability are some desirable requirementsfor future devices. Additionally, the easy transfer of the measuredvalues to a device which is connected to a tele-monitoring system,are future perspectives and requirements for new blood-glucose de-vices.
Actual commercial available blood-glucose meters have differentdrawbacks. The displays have only limited viewing possibilities likecharacter size, different colors and graphical display possibilities. Theresults are only saved on the device, and therefore other authorizedpersons have no access to the data. Furthermore, a blood-glucosemeter needs a battery, which can be a problem, when it needs to
be changed or the device is used in a cold environment (belowzero).
The application of NFC can help to enhance the simple handlingof the blood-glucose measurement. More and more smartphoneson the market have a NFC-interface built inside. The developed NFC-based blood-glucose meter uses the NFC-interface of a smartphonefor transferring measurement data, and energy for the power supplyof the measurement sensor unit.
With this approach, the size of the blood glucose-meter itself canbe reduced radically. There is no need for a display, battery anda storage unit for the measurements anymore. Therefore, the sizeof the NFC-based blood glucose-meter can be reduced to the sizeof a credit card (see [5]). The results are displayed on the screenof the smartphone and the touch screen of the smartphone canbe used for operating the blood-glucose measurement. Even themeasurement data can be saved in the data storage of the smart-phone. All additional functions of the smartphone like data trans-fer, visualization of the results and many more features can beused for a more comfortable measurement and therapy manage-ment.
In Fig. 9, the block diagram of the concept of the NFC-basedblood-glucose meter is shown. Part 2 and 9 of the block diagramare the NFC-coils of the smartphone and the developed NFC-basedblood-glucose meter. Between these two coils the commands ofthe smartphone to the device, results from the measurement tothe smartphone and supply of energy is transferred. The coil ofthe device has to be tuned exactly, that the transfer of data andenergy can occur at the same time. Parallel to the NFC-coil is theintegrated NFC-chip (part 4), which controls the NFC-data trans-fer in both directions. Part 3 generates the DC-voltage for the
Fig. 9. Schematic block diagram of the NFC-based blood-glucose meter [5]
ORIGINALARBEITEN S. Cecil et al. Smart NFC-sensors for healthcare applications and further development
Fig. 10. Voltage at the 1500 Ohm resistor for different resonance capacities with the prototypes of the blood-glucose meter power supply forthe Google Nexus and the Nokia 6212 NFC-interface
supply of the device from the 13.56 MHz NFC-signal (energy har-vesting). If needed, some energy can be stored in an optional en-ergy storage (part 5). The generated voltage has to be limited. Thiscan be done by a DC-DC-converter or by a simple voltage limita-tion with a Zener-diode or a LED (Part 6). In any case, the usergets an optical feedback that there is enough energy available forstarting the measurement. Part 7 is the measurement sensor unitwith the slot for a test-strip and the electronic for the measure-ment.
Essentially for the functionality of the NFC-based blood-glucosemeter is the transfer of data and supply of energy at the sametime via the same interface. For the test of the prototype thismeans, that the NFC-chip (part 4 in Fig. 9) has to answer via theNFC-connection and at the same time there has to be approxi-mately 5 mW of energy available for the blood-glucose measure-ment unit (part 7). The input impedance of a typical blood-glucosemeasurement unit was determined at 1500 Ohm and it was re-placed by a corresponding resistor, so that a voltage of at least2.7 V is needed for supplying the blood-glucose measurement unitwith sufficient energy. Three different prototypes with two smart-phones were tested. All prototypes consisted of a NFC-coil with twoturns and a rectifier inside the turns. Prototype 1 and 2 have a coilarea of 35 × 65 mm, and prototype 2 has an additional metallicplane in the free place in the middle of the turns. Prototype 3 hasa coil area of 75 × 55 mm and also a metallic plane in the middleof the turns. The metallic plane represents all additional electronicparts, which will be placed in the middle of the NFC-coil in furtherdesigns. The NFC-coils were tuned by changing the tuning capac-ity (between part 3 and 4), which is in parallel to the NFC-coil. InFig. 10 the results of the tuning of the NFC-coil of some prototypesare shown.
For all prototypes the resonance capacity with the highest volt-age at the 1500 Ohm resistor was evaluated applying the GoogleNexus smartphone. For prototype 1 the resonance capacity, usingthe Nokia 6212 phone, was evaluated too.
First of all, it should be noticed, that the NFC-chip (Typ A, ISO/IEC14443, Mifare Classic 1k, input capacitance 19 pF) could be readout at all tested configurations. For prototype 1 the measurementsresulted in an optimal resonance capacity of 270 pF with the Nexussmartphone. With the Nokia 6212 phone the optimal resonance ca-pacity was 220 pF. These results show that the type of smartphone
has an impact on the optimal resonance capacity. Prototype 2 gainedthe highest output voltage with an optimal capacity of 150 pF butthe output voltage was nearly constant between 0 pF to 220 pF.This means, a conducting area inside the NFC-coil (e.g. the blood-glucose meter) changes the resonance behavior too. In the investi-gated prototype 2 the output voltage stays nearly constant over abig range of capacity. Prototype 3 showed its resonance at a capac-ity of 82 pF and a very small range of applicable capacity in order tohave enough voltage to take a measurement.
The determination of the resonance capacity showed, that thereare many influencing factors on the optimal capacity. Therefore, theapplied resonance capacity has to be chosen carefully, so that alldifferent designs and applied NFC interfaces can provide the energyfor the measurement procedure, while the NFC-connection is trans-ferring data.
For the measurement with the new NFC-based blood-glucose me-ter, a stable connection to the NFC-interface of the smartphone isneeded. For an easy to use handling, the device needs to be fixedonto the back of the smartphone. This can be done with varioustechniques: magnetic fixing, advanced hook and pile strips, nan-otechnology surfaces or mechanical latching.
When the NFC-based blood-glucose meter has established a sta-ble NFC-connection, the corresponding software App on the smart-phone is started and the blood-glucose meter can be controlled viathe touchscreen of the smartphone. The data of previous measure-ments can be displayed or a new measurement can be started viathe app.
A big advantage of the blood-glucose measurement with thesmartphone is the possibility of a connection to any online data baseduring the measurement. Therefore, the result of the measurementcan be saved immediately, e.g. in a personal data storage or sent toauthorized persons. Additionally needed data for the security checksof the measurement or a check to establish whether the test-stripsare originals, can be down loaded, e.g. from a server of the manu-facturer of the device and the test-strips. The features of a classicalglucose-meter and the new NFC-based glucose-meter are illustratedin Fig. 11.
5. NFC-based low-cost cryo-sensor for vialsCooling chain interruptions during handling and transportation ofbiological materials are critical, as the material may be seriously dam-
ORIGINALARBEITEN S. Cecil et al. Smart NFC-sensors for healthcare applications and further development
aged. Therefore, a cost efficient system that reliably detects such in-terruptions is desired in many cases, as it can prevent the furtheruse of potentially affected biological materials. For example, somebiological materials are stored in tanks with liquid nitrogen at mi-nus 196 ◦C. Each material sample is contained in a vial and severalvials are contained in a rack which is submersed in liquid nitrogen.This means, when a material sample (vial) is required the whole rackmust be taken out of the tank, the requested vial is taken out ofthe rack and afterwards the rack is returned into the tank as fast aspossible. The requested vial, of course, needs to be put in a separatecooling unit until it reaches its final destination. In case of delays ormishandling during taking out vials from the tank or problems withthe cooling of the requested vial it may happen that vials temporarilyexperience significant temperature increase, e.g. higher than minus100 ◦C. In such cases the biological sample may have been adverselyaffected and its further use should be avoided.
Triggered by the particular demand of a potential project part-ner, a smart cryo-sensor was developed which enables the reliabledetection of a single cooling chain interruption.
The concept is based on a bimetal strip, a ratch mechanism anda thin breakable electrically conductive rod (e.g. graphite rod). Thebasic outline and functional principle is shown in Fig. 12.
A bimetal strip and a breakable thin electrically conductive rodare arranged in parallel next to each other. One end of the break-able thin electrically conductive rod and one end of the bimetal stripare fixed in a stiff U-shaped (or L-shaped) holder. On the free end ofthe bimetal strip, a ratch sleeve is mounted in which a correspondingratch rod is partly inserted. The ratch sleeve and ratch rod are de-signed in a way that a relative movement of the two parts is possibleonly in one direction (Fig. 12, top).
The main and important feature of the system is that it automat-ically activates itself during the first freezing process as follows: Thedecreasing temperature causes the bimetal strip to bend downwards(towards the holder). At the same time this causes the ratch sleeveto make a relative movement against the ratch rod because the ratch
rod adjoins at the holder and cannot move downwards. By choos-ing appropriate dimensions, the ratch rod is fully inserted into theratch sleeve when the target storage temperature (e.g. −196 ◦C)is reached. The system remains in this stage as long as the storagetemperature is kept (Fig. 12, center).
When the temperature increases (e.g. due to a temporal interrup-tion of the cooling chain) the bimetal strip together with the ratchsleeve and ratch rod moves upwards and at a certain temperaturethe ratch rod starts to exert an upwards directed mechanical bend-ing force on the breakable thin electrically conductive rod. As longas the temperature increases the bending force increases until theconductive rod breaks. The breaking of the conductive rod is a non-resettable response which can easily be evaluated, either by elec-trical means or even visually. By choosing appropriate dimensionsand materials the required threshold temperature (e.g. −100 ◦C), atwhich the system shall respond, can be defined.
In a miniaturized version, such a sensor is low cost and can be at-tached to each vial containing temperature sensitive biological ma-terials. In practice, every vial which is taken out from the coolingchain can then be checked if the cooling chain was continuouslyclosed or if there was any (even a single) interruption. Checking caneither be performed visually or electrically, in the most convenientway by using RFID or NFC technology, when the sensor is equippedwith a corresponding transponder enabling a contactless readout ofthe sensor status.
6. NFC-based ultraviolet assessmentOverexposure to ultraviolet (UV) radiation induces photochemicaldamage of skin cells (causing the commonly well-known sun burn)and is presently seen as the most frequent cause of skin cancer.Presently available personal UV-monitors are battery powered stand-alone devices. These are expensive because they need to containall required components (sensor diodes, signal processing, measure-ment control, post-processing of the measurement results, etc.). Thedevelopment described here shifts the sensor front-end and the min-imum required ultra-low power electronic circuitry into a slim low-
Fig. 13. Basic outline of the NFC-based UV assessment. Top: schematic block diagram; bottom: outline of smart transponder and usage in practice
S. Cecil et al. Smart NFC-sensors for healthcare applications and further development ORIGINALARBEITEN
cost and passive smart NFC transponder. All other required stepsare carried out by the corresponding App on the user’s smartphone,thereby creating a robust, low-cost and reliable personal UV mon-itoring device for the mass market. The system consists of a sim-ple, robust and slim low-cost UV-sensor integrated into a smarttransponder (e.g., in smart card format). The measured raw dataare transferred to the smartphone with corresponding App via NFC.In order to keep the sensor small and low-cost a broadband pho-todiode overlaid with an appropriate UV-filter is used (Fig. 13). Thecutback of the broadband measurement, i.e. that the measured UVintensity does not contain any spectral information, can be compen-sated by the App on the smartphone, based on actual GPS- and timedata as well as data obtainable from global UV-radiation databases(locally stored on the phone or via real time access). Based on ad-ditionally available personal data (skin type, sun tan lotion, etc.) theindividual maximum exposure time can be estimated. In summary,this device therefore brings both a health benefit for the end user aswell as an added value for cosmetic industries.
7. Future perspectives of NFC for sensingIn healthcare, the systems for data capturing of vital patient datahave to be easy to use, reliable and fast. In healthcare scenariosyou always have the need to measure biosignals but also to ask thepatient for other information such as wellbeing, pill intake, physicalactivities, bread units and much more depending on the disease. Inthe need of a technology which can measure or capture all this data,NFC is the only technology where electronically measured values andnon-electronic information can be captured with the same protocoland device.
One of the features of NFC making it especially suited for health-care applications and usage by technically poorly skilled or impairedpersons is, that the communication is started by just bringing thetwo peers close to each other, i.e. no additional action for initi-ating the data exchange by the user is necessary. Taking into ac-count that NFC is already being integrated in more and more mobilephones, and the high penetration of mobile phones in the popu-lation, NFC offers the possibility for a wide variety of useful appli-
cations not only in healthcare and care applications but in manyareas.
The described example of a very smart UV sensor solution basedon a NFC interface for a perfect sun protection, wherever you areon this planet, shows that beyond healthcare and AAL applicationsthere are much more possible NFC sensing applications just waitingto be invented and realized in future.
Ticketing and payment are available on the market since 15 re-spectively 5 to 10 years. This market with high chip volumes (severalhundred million chips per year) generates cost-efficient chip plat-forms which can be used with minor or major modifications for
NFC sensing tasks. This opens a variety of applications which canincrease usability and comfort as well as are more useful for humansthan probably payment and ticketing. This helps to push NFC ap-plications further forward via use cases with high impacts for theindividual user.
In short, with NFC sensing, more valuable and easy to use ap-plications are possible at reasonable costs than with other wirelesscommunication technologies!
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Authors
Stefan Cecilreceived his M.Sc. degree in Electrical Engi-neering, Industrial Electronics and AutomaticControl Engineering from the Vienna Univer-sity of Technology, Austria, in 2003. Since2004 he has been scientist in the Seibers-dorf Laboratories in the expert group “Elec-tromagnetic Compatibility”. There he joinedseveral projects on problems of electromag-netic compatibility, human exposition and an-
tenna design, especially the design of NFC-antennas. His researchis in the area of application of numerical simulations of electro-magnetic fields with different simulation tools (Finite Difference inTime Domain (FDTD), Method of Moments, Ray-tracing-Tools, Low-Frequency-algorithms). He has managed several projects with theaim of the electromagnetic compatibility of electronic implants, dis-persion of electric current in the human body and human safetydistances at different electromagnetic sources.In this area of investigation and research Stefan Cecil has authoredor co-authored more than 25 conference and technical papers.
Manfred Bammerreceived his M.Sc. (Dipl.-Ing.) in Electrical En-gineering, Industrial Electronics and Auto-matic Control Engineering from the ViennaUniversity of Technology, Austria in 1991 andhis MAS degree in Communication and Man-agement Development from the Danube Uni-versity Krems in 2001.Manfred Bammer joined the AIT Austrian In-stitute of Technology in 1993, where he is
head of the Business Unit Biomedical Systems and inventor as wellas creator of the project “Next Generation NFC Applications” whichis a co-operation between AIT Austrian Institute of Technology andSeibersdorf Laboratories. In parallel, Manfred Bammer is the safetyofficer for medical device development of AIT and he has devel-oped the lecture “Medical device technology—Regulatory affairsand quality management” in the Master thesis course “Healthcareand Rehabilitation Technology” for the University of Applied Sci-ences Technikum Vienna, Austria.
ORIGINALARBEITEN S. Cecil et al. Smart NFC-sensors for healthcare applications and further development
Manfred Bammer has authored or co-authored more than 20 con-ference and technical papers in the fields of NFC (Near Field Com-munication) and is co-inventor of about 10 NFC patents pending.Manfred Bammer has also a long track record bringing applied re-search inventions with his team to a state where they can easilybe commercialized e.g. non-invasive pulse wave analysis algorithms(ARCSolver) for cardiovascular risk stratification is already certified byCE, FDA and JPAL and used by more than 2.000 physicians world-wide or the plasmo process observer system for on-line inspectingof laser welding, laser drilling etc. which led to the founding of anown company plasmo Industrietechnik GmbH. The system is alreadyused by all major car producers and their equipment suppliers foron-line quality control.
Gernot Schmidwas born in Vienna, Austria, in 1969. He re-ceived the M.Sc. degree in Electrical Engineer-ing from the Vienna University of Technologyin 1997. Since 1997 he has been with the ex-pert group “Electromagnetic Compatibility”as Senior Applied Researcher, Project Man-ager and Deputy Head. He has been work-ing on numerous national as well as interna-tional research projects related to the expo-
sure assessment in electromagnetic fields, the biological impact ofelectromagnetic fields, and electromagnetic interference of medicalimplants. Moreover, since 2009 he has been involved in the devel-opment of NFC sensor applications. Gernot Schmid is member ofthe expert group on EMF of the Austrian Federal Ministry of Health.He is author/co-author of 18 refereed articles in SCI-listed journals,more than 90 conference papers, numerous research project reportsand holder of several NFC-related patents. He serves as reviewerfor several SCI-listed journals (Physics in Medicine and Biology, Bio-electromagnetics, Health Physics, Physiological Measurements, Radi-ation Protection Dosimetry, Radiation Research) and is a member ofthe Bioelectromagnetics Society (BEMS) and the European Bioelec-tromagnetic Association (EBEA).
Kurt Lamedschwandnerreceived his M.Sc. (Dipl.-Ing.) in electrical en-gineering from the Vienna University of Tech-nology, Austria, in 1993, his MBA degreefrom Webster University Vienna in 2001 andhis Ph.D. (Dr. techn.) from the Johannes Ke-pler University Linz, Austria in 2009.Kurt joined the Seibersdorf Laboratories in1993 where he is head of the expert group“Electromagnetic Compatibility” and leader
of the project “Next Generation NFC Applications” which is a co-operation between the AIT Austrian Institute of Technology and theSeibersdorf Laboratories. In parallel he is lecturer on EMC at the Vi-enna University of Technology, at the University of Applied SciencesTechnikum Vienna and at the University of Applied Sciences CampusVienna.Since 1996 he has been member of the Working Group EMC of theAustrian Electrotechnical Association (OVE), since 1999 he serves aschair of the IEEE EMC Austria Chapter. Kurt Lamedschwandner hasauthored or co-authored more than 70 conference and technicalpapers in the fields of EMC (Electromagnetic Compatibility), EMF(personal exposure in Electromagnetic Fields) and NFC (Near FieldCommunication).
Andreas Oberleitnerreceived his M.Sc. (Dipl.-Ing.) in Electrical andBiomedical Engineering from the TechnicalUniversity of Graz, Austria, in 2004. Afterfinishing his studies, he joined the AIT Aus-trian Institute of Technology GmbH as an en-gineer in charge of hardware developmentof medical devices. His main focus lies onthe project management and development ofnon-invasive diagnostic and therapeutic de-
vices, especially for cardiology and AAL.Oberleitner is a certified regulatory affairs expert for medical devicesand member of the OVE TK MG, the technical standardisation groupfor medical devices. In parallel he is lecturer on regulatory affairs formedical devices at the University of Applied Sciences Technikum Vi-enna, Austria.
