**5. Design procedure**

In (Paffi et al., 2010) a standardized procedure was proposed for reaching the optimum exposure design. It consists of seven main steps, as schematically shown in Fig. 3.

Fig. 3. Flow chart of the standardized procedure for the design and characterization of exposure systems

300 Real-Time Systems, Architecture, Scheduling, and Application

continuous waves (CW) or modulated signals, especially at the frequencies typical of mobile communication. In one case (Pakhomov et al., 2003), the effects of a pulsed signal at 9 GHz

Due to the complexity of the experimental procedure, generally exposure systems for realtime experiments are more difficult to design since, beside the requirements typical of any exposure system (see Section 2), they have to meet additional and demanding requirements

In particular, for *in vivo* experiments, only two real-time systems are present in the literature from 1999 until now (Testilier et al., 2002; Arima et al., 2011). Both of them are based on a simple EM structure (i.e. an antenna), while the real-time monitoring of the biological parameter is obtained through highly invasive techniques. In Testilier et al. (2002) neurotransmitter levels in a rat brain were monitored during the exposure through an invasive microdialysis technique; in Arima et al. (2011) the microcirculation of the rat brain

The reason of such a reduced number of *in vivo* studies can be found in bioassays typically used to measure the effects of EM fields that require the employment of complex procedures and instrumentation. Biological data are often collected after the animal sacrifice and the

In (Paffi et al., 2010) a standardized procedure was proposed for reaching the optimum

exposure design. It consists of seven main steps, as schematically shown in Fig. 3.

Fig. 3. Flow chart of the standardized procedure for the design and characterization of

during the exposure is observed through a cranial window on the skull.

subsequent removal of organs and tissues for the analysis.

on brain slices were investigated.

(see Section 5).

**5. Design procedure** 

exposure systems

Before carrying out the experimental activity, a hypothesis is formulated (step 1), leading to the choice of an appropriate biological system to be exposed. It can be a particular kind of cell, a tissue, an organ, or a whole organism, as an animal. The experiment to test the hypothesis is then defined (step 2), including biological models, endpoints, techniques, and exposure parameters. The outcome of the analyses carried out during this step determines all the requirements, both biological and EM, of the exposure system. Moving from biological protocol and requirements on exposure parameters, the most suitable EM basic structure is chosen (step 3). If a system meeting all the requirements for the planned experiment is already present in the literature, one may decide to use that system as it is or to adapt it to new constrains; otherwise, the chosen EM structure must be first dimensioned on theoretical bases (step 4). Generally, the basic structure must be modified in order to meet all the biological and EM requirements. Thus, an iterative process of adaptation and optimization of the system (step 5) takes place using numerical tools, leading to the nal design parameters (dimensions, materials, sample position, etc.). The next two steps are the manufacture (step 6) and the experimental validation (step 7) of the exposure system. Measurements should be conducted firstly with the empty structure; then it has to be loaded with the biological sample to validate the behavior of the system and to experimentally evaluate the dosimetry, i.e. the SAR distribution in the sample. If acceptable agreement between measurement and simulation is not achieved, one must return to steps 5, 6, or 7 depending on the hypothesized cause of mismatch.

As already noted, biological requirements represent a crucial point for the design of an exposure system since they could be the most limiting ones, especially when a particular equipment and protocol procedures are needed, e.g. in real-time experiments.
