**4. Methods**

#### **a. Review of literature**

The ratio of penetration of SRD and its real effectiveness in healthcare remain unknown. This work reviews technological advances on SRD, produced from 2001 to 2011, to be applied in healthcare scenarios and mainly in AAL ones.

A more careful reading of the summaries showed that selected papers not always matched with the focus of this review. The found papers using search engines contained the words we were looking for but they were not always in the proper context. Search engines usually work using orthographical criteria and not semantic ones and this is a great weakness in automated

**Figure 2.** Selected models of social alarm devices: (a) AMIE+ Tunstall, (b) Neat Atom, (c) TX4 Bosch, (d) S37 TeleAlarm

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The systems of social alarm devices consist of two operational units: the buttons that are worn by the users typically hung over the neck or attached at the wrist, and the fixed unit that is connected to the home phone. When the user is in a distress situation, he can push the button, a radio frequency signal will be transmitted to the fixed unit and an emergency phone call will

The buttons transmit a signal that typically consists of three pulses (depending on the model) at the frequency of 869.21 MHz. These are emissions in domestic settings that can affect the electromagnetic environments and can involve the increase in the exposure to electromagnetic

Laboratory measurements have been carried out to characterize and analyse the RF emissions of the more extended social alarm devices. The objectives were to obtain the radiation pattern in order to identify the position when the electric field is at a maximum, and to calculate the power density and the Equivalent Isotropically Radiated Power (EIRP) for each of the tested

The electric field strength and other parameters of the emissions of the device under testing

The performed environmental study of the working conditions of the social alarm devices helps to quantify the exposure of assisted people and to analyse the EMC of networks and

For this work five models of social alarm devices were chosen from among the most frequently used in telecare monitoring activities. These devices AMIE+ Tunstall, Neat Atom, TX4 Bosch,

The measurements were performed in a semianechoic chamber, shown in Figure 3 and Figure 4. The room has dimensions of 9,76 m x 6,71 m x 6,10 m, the walls are lined with a foam based

have been measured to examine the compliance with exposure guidelines.

S37 TeleAlarm and System 5000 Smart Call, are shown in Figure 2.

**b. Measurements: electromagnetic laboratory evaluation**

fields of users, patients, medical workers and people in general.

equipment that operate in the surrounding areas.

searches.

devices.

be made to the monitor centre.

and (e) System 5000 Smart Call.

The research methodology employed for examining the adoption of SRD in healthcare has been divided into four phases: literature collection, categorization of the selected papers, analysis of the publications included in every category and results.

#### **Search strategy**

Both automatic and manual searches were carried out on professional databases including EMBASE, MEDLINE and PUBMED in order to identify relevant articles published between 2001 and 2011. The keywords used in the searching areas of title, keywords and abstract were a combination of 'short range device (or devices)', 'short range technology (or technologies)', 'radiofrecuency, 'rfid (and synonyms)', 'bluetooth', 'near field communication', 'wlan', 'uwb' and finally 'humans'. The number of papers initially located was 653. After eliminating duplicates and other inaccurate results, 378 were excluded and 275 were finally taken into account. Other systematic reviews carried out by different authors some years or months before were also very useful in identifying and including relevant studies not located by search engines.

Publication types reviewed were: Article, Article in Press, Conference Abstract, Conference Paper, Conference Review, Editorial, Erratum, Letter, Note, Review and Short Survey. Editorials, Letters, and Opinion Papers were excluded as well as those studies which dealt with ethical and legal aspects. No restrictions were imposed on the quality of the study design.

#### **Data synthesis**

Two authors independently reviewed the selected papers in order to classify them into one of the following categories at least:


**Figure 2.** Selected models of social alarm devices: (a) AMIE+ Tunstall, (b) Neat Atom, (c) TX4 Bosch, (d) S37 TeleAlarm and (e) System 5000 Smart Call.

A more careful reading of the summaries showed that selected papers not always matched with the focus of this review. The found papers using search engines contained the words we were looking for but they were not always in the proper context. Search engines usually work using orthographical criteria and not semantic ones and this is a great weakness in automated searches.

#### **b. Measurements: electromagnetic laboratory evaluation**

transmission, and microamperes when in the sleep mode. The lifespan of the battery may be

The ratio of penetration of SRD and its real effectiveness in healthcare remain unknown. This work reviews technological advances on SRD, produced from 2001 to 2011, to be applied in

The research methodology employed for examining the adoption of SRD in healthcare has been divided into four phases: literature collection, categorization of the selected papers,

Both automatic and manual searches were carried out on professional databases including EMBASE, MEDLINE and PUBMED in order to identify relevant articles published between 2001 and 2011. The keywords used in the searching areas of title, keywords and abstract were a combination of 'short range device (or devices)', 'short range technology (or technologies)', 'radiofrecuency, 'rfid (and synonyms)', 'bluetooth', 'near field communication', 'wlan', 'uwb' and finally 'humans'. The number of papers initially located was 653. After eliminating duplicates and other inaccurate results, 378 were excluded and 275 were finally taken into account. Other systematic reviews carried out by different authors some years or months before were also very useful in identifying and including relevant studies not located by search

Publication types reviewed were: Article, Article in Press, Conference Abstract, Conference Paper, Conference Review, Editorial, Erratum, Letter, Note, Review and Short Survey. Editorials, Letters, and Opinion Papers were excluded as well as those studies which dealt with ethical and legal aspects. No restrictions were imposed on the quality of the study design.

Two authors independently reviewed the selected papers in order to classify them into one of

calculated in terms of tens of days.

healthcare scenarios and mainly in AAL ones.

analysis of the publications included in every category and results.

**4. Methods**

148 Telemedicine

**Search strategy**

engines.

**Data synthesis**

the following categories at least: **•** Electromagnetic compatibility **•** Electromagnetic health risks

**•** Monitored environments **•** Ambient assisted living **•** Technological assessment

**•** Electromagnetic effects on the biological tissues

**a. Review of literature**

The systems of social alarm devices consist of two operational units: the buttons that are worn by the users typically hung over the neck or attached at the wrist, and the fixed unit that is connected to the home phone. When the user is in a distress situation, he can push the button, a radio frequency signal will be transmitted to the fixed unit and an emergency phone call will be made to the monitor centre.

The buttons transmit a signal that typically consists of three pulses (depending on the model) at the frequency of 869.21 MHz. These are emissions in domestic settings that can affect the electromagnetic environments and can involve the increase in the exposure to electromagnetic fields of users, patients, medical workers and people in general.

Laboratory measurements have been carried out to characterize and analyse the RF emissions of the more extended social alarm devices. The objectives were to obtain the radiation pattern in order to identify the position when the electric field is at a maximum, and to calculate the power density and the Equivalent Isotropically Radiated Power (EIRP) for each of the tested devices.

The electric field strength and other parameters of the emissions of the device under testing have been measured to examine the compliance with exposure guidelines.

The performed environmental study of the working conditions of the social alarm devices helps to quantify the exposure of assisted people and to analyse the EMC of networks and equipment that operate in the surrounding areas.

For this work five models of social alarm devices were chosen from among the most frequently used in telecare monitoring activities. These devices AMIE+ Tunstall, Neat Atom, TX4 Bosch, S37 TeleAlarm and System 5000 Smart Call, are shown in Figure 2.

The measurements were performed in a semianechoic chamber, shown in Figure 3 and Figure 4. The room has dimensions of 9,76 m x 6,71 m x 6,10 m, the walls are lined with a foam based radiofrequency absorber material (RANTEC Ferrosorb300) specified to have a reflection/ absorption coefficient of -18 dB at the frequency of 869.21 MHz.

All of the measurements during this work were made in the far field region with respect to the sources. At 869.21 MHz, the wavelength is about 34 cm, which means the reactive near field extends to around 5.5 cm from the source (based on the usual λ/2π criterion, where λ is the wavelength). The antennas of the social alarm devices are no more than around 5 cm in size, and they are integrated inside the casing device. Hence, the radiating near field extends no further than around 1.5 cm at 869.21 MHz (based on the usual 2D2 /λ criterion, where D is the maximum source dimension).

The devices tested were mounted on a manual positioning device with an EMCO 1060 motor, allowing the device to be rotated and permitted the measuring antenna to sample the radiation pattern at any angle. All the measurements were performed in vertical and horizontal polarizations; a positioner with an EMCO 1051 motor allows the changes of the position of the measuring antenna that is a VBAA-9144 Schwarzbeck biconical antenna with a frequency range of 80 MHz - 1 GHz. The instruments and devices used to obtain the radiation pattern are shown in Figure 3.

FSM 016, with an HD10 controller to move it automatically. This positioning device is shown

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**Figure 4.** Radiation pattern of two models of social alarm devices: (a) AMIE+ Tunstall, and (b) Neat Atom.

**Figure 5.** Measuring antenna and positioners required for the E-field measurements inside the anechoic chamber.

The measurements were carried out with an EMI Test Receiver ESIB26, Rhode & Schwartz with a frequency range of 20 Hz - 26.5 GHz. The EMI test receiver calculates the electric field strength taking into account the antenna factor and the cable attenuation, according to the

in Figure 5.

following equation [16]:

**Figure 3.** Measuring antenna and positioning devices to obtain the radiation pattern inside the anechoic chamber.

The radiation pattern of the models (a) AMIE+ Tunstall, and (b) Neat Atom are shown in Figure 4.

After obtaining the radiation pattern, the position of each tested device at which the electric field strength is maximum was fixed. In that position the electric field strength was measured as a function of distance in horizontal and vertical polarization in the far field region in steps of 10 cm, from 0.2 m to 1.7 m. The positioning device used to determine the distances was a Short Range Technologies for Ambient Assisted Living Systems in Telemedicine: New Healthcare Environments http://dx.doi.org/10.5772/57020 151

radiofrequency absorber material (RANTEC Ferrosorb300) specified to have a reflection/

All of the measurements during this work were made in the far field region with respect to the sources. At 869.21 MHz, the wavelength is about 34 cm, which means the reactive near field extends to around 5.5 cm from the source (based on the usual λ/2π criterion, where λ is the wavelength). The antennas of the social alarm devices are no more than around 5 cm in size, and they are integrated inside the casing device. Hence, the radiating near field extends

The devices tested were mounted on a manual positioning device with an EMCO 1060 motor, allowing the device to be rotated and permitted the measuring antenna to sample the radiation pattern at any angle. All the measurements were performed in vertical and horizontal polarizations; a positioner with an EMCO 1051 motor allows the changes of the position of the measuring antenna that is a VBAA-9144 Schwarzbeck biconical antenna with a frequency range of 80 MHz - 1 GHz. The instruments and devices used to obtain the radiation pattern

**Figure 3.** Measuring antenna and positioning devices to obtain the radiation pattern inside the anechoic chamber.

The radiation pattern of the models (a) AMIE+ Tunstall, and (b) Neat Atom are shown in

After obtaining the radiation pattern, the position of each tested device at which the electric field strength is maximum was fixed. In that position the electric field strength was measured as a function of distance in horizontal and vertical polarization in the far field region in steps of 10 cm, from 0.2 m to 1.7 m. The positioning device used to determine the distances was a

/λ criterion, where D is

absorption coefficient of -18 dB at the frequency of 869.21 MHz.

no further than around 1.5 cm at 869.21 MHz (based on the usual 2D2

the maximum source dimension).

are shown in Figure 3.

150 Telemedicine

Figure 4.

**Figure 4.** Radiation pattern of two models of social alarm devices: (a) AMIE+ Tunstall, and (b) Neat Atom.

FSM 016, with an HD10 controller to move it automatically. This positioning device is shown in Figure 5.

**Figure 5.** Measuring antenna and positioners required for the E-field measurements inside the anechoic chamber.

The measurements were carried out with an EMI Test Receiver ESIB26, Rhode & Schwartz with a frequency range of 20 Hz - 26.5 GHz. The EMI test receiver calculates the electric field strength taking into account the antenna factor and the cable attenuation, according to the following equation [16]:

$$E = V + AF + ATT \tag{1}$$

Decision 2006/771/EC on harmonisation of the radio spectrum for use by short-range devices (2011/829/EU) [15], and the Spanish National Table of Spectrum Location (ITC/332/2010) [17].

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Although most of the papers collected only partially cover the subject matter, the research performed for this chapter clearly demonstrates the high number of publications related to

The number of papers seems to have increased significantly since 2001 as Figure 6 shows. The

248 papers finally included in our review were classified into six categories.

**Figure 6.** Papers which mention SRD technology in healthcare from 2001 to 2011 (Npapers: 248)

However, it is important to note the lack of publications which evaluate the effectiveness of SRD in real healthcare scenarios and most of the studies found only cover technological issues

In this work, the two categories which are of most interest to the authors are AAL and monitored environments. Both characterize more complex scenarios, where SRD are combined with sensors to work together in a wireless network, finally connected to remote information repositories of data and software, as presented in Figure 1. Reducing hospital admissions and length of stay are main objectives in order to save economic and human resources, as well as to improve a patient's quality of life. However, most of these outpatients are elderly, or have

**5. Results**

**a. Review of literature**

as is shown in Figure 7.

SRD in healthcare during recent years.

Where E is the electric field strength (dBuV/m), V is the measured voltage (dBuV), AF is the antenna factor (dBm−1), and ATT is the cable attenuation (dB). After obtaining the horizontal and vertical components, the total field strength was calculated. The power density was derived using the following equation:

$$S = EH = \frac{E^2}{377} \tag{2}$$

Where the unit of S is W/m2 and E has now been converted to linear units. The EIRP of each tested device was calculated for comparison with the emission limit of 16.4 mW set by standard regulations [15][17]. EIRP is the power that would have to be emitted if the antenna were isotropic in order to produce a power density equal to that observed in the direction of maximum gain of the actual antenna.

The EIRP is obtained from the power density as follows:

$$EIRP = 4\pi r^2 \mathcal{S}\_{\text{max}} \tag{3}$$

Where EIRP is in units of W, r is the distance to the antenna in meters, and Smax(r) is the maximum power density measured at each distance in W/m2 . The EIRP was calculated using the maximum measurement of power density, so the measurements of the electric field strength were realized in the direction of maximum radiation.

#### **c. Compliance with exposure levels threshold**

This research addresses the characterization of EM environments that are actually present in households, taking into account an analysis of the potential safe usage of domestic telemedi‐ cine systems. The data had been analysed with regard to potential risks and operational disturbances in accordance with existing European standards.

The field strength recorded from the tested devices have been compared with the correspond‐ ing International Commission on Non-ionizing Radiation Protection (ICNIRP) reference levels values defined for the general public depending on the working frequency [18].

It is also useful to compare the obtained levels with the thresholds for the safety and basic performance of the electromedical equipment. The International Electrotechnical Commission (IEC) Standard IEC 60601-1-2 [19], sets a minimum immunity level of 3 (V/m) for non-life supporting devices.

After calculating the parameters that characterize the emissions of the social alarm devices under testing, the results recorded are compared with the limit values set by the national and international bodies: Commission Implementing Decision of 8 December 2011 amending Decision 2006/771/EC on harmonisation of the radio spectrum for use by short-range devices (2011/829/EU) [15], and the Spanish National Table of Spectrum Location (ITC/332/2010) [17].
