**6.2 Real time systems in the literature**

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

However, the power efficiency is quite low (Paffi et al., 2011). Propagating systems are mainly based on rectangular or radial waveguides (Hansen et al., 1999), whereas resonant cavities are mainly obtained by shorting radial waveguides through metallic rods (Balzano et al., 2000). These structures are characterized by high volume efficiency, i.e. a lot of bodies (up to 65 animals) can be simultaneously exposed in a limited space. However, due to the importance of a correct body positioning, animals are restrained within plastic cylinders. Therefore, resonant cavities are suitable for chronic long-term (days or moths) exposures only if the exposure is limited to a few hours per day, as done in some two years bioassay

A separated mention must be made of reverberating chambers (Corona et al., 2001). Inside those systems a statistically uniform field can be obtained and a large number of animals can be simultaneously exposed in a habitat simulating the usual one of animals (Wu et al., 2010). These are the reasons why they are suitable for large-scale, long-term

Moving to the *in vitro* systems, among the 54 off-line setups found in the literature, the most used (24) are propagating structures (Paffi et al., 2010), such as Transverse Electromagnetic (TEM) cells and rectangular waveguides. The main advantages of propagating structures are the EM field uniformity inside the biological sample and versatility. With a proper dosimetric characterization, propagating systems have been used to expose different volumes of various kinds of cells inside sample holders, such as multiwells, Petri dishes, and flasks (Paffi et al., 2010). Also resonant systems have been largely used (12) in off-line *in vitro* experiments (Paffi et al., 2010). They are closed and compact structures, such as shortcircuited waveguides; thus both the active and the sham systems easily fit inside a commercial incubator, often needed for maintaining the optimal environmental conditions (Schuderer et al., 2004). Due to the onset of a standing wave inside resonant systems, the power efficiency is generally high, but the positioning of the sample is critical, because of the extremely localized regions of field uniformity (Paffi et al., 2010). On the contrary, radiating systems, usually consisting of commercial or ad hoc fabricated antennas, present low power efficiency, but generally allow for the simultaneous exposure of a lot of samples. However, they need EM compatible arrangements due to the lack of enclosures confining

Regarding the 13 real-time *in vitro* systems, they are mostly based on propagating structures, with the only exception of one resonant (Hagan et al., 2004) and one radiating system (Yoon et al., 2006). Indeed, propagating structures are generally the most versatile

To meet such requirements, two main solutions have been proposed in the literature (Paffi et al., 2010): closed structures modified with holes for sample observation and data recording and open systems specially designed to have the field confined in a small volume around the surface. This latter solution also implies high values of power efficiency (Liberti

A detailed description of different kinds of real-time systems, together with their main

and adaptable to the additional constrains imposed by real-time acquisition.

experiments (e.g. PERFORM A).

the emitted field (Paffi et al., 2010).

et al., 2004; Paffi et al., 2007).

features, will be given in Section 6.2.

experiments.

According to the classification described above, real-time *in vitro* systems published in international journals from 1999 up to now, have been organized in a schematic view in Table 2.


Table 2. Classification of the real-time *in vitro* systems published from 1999
