**7. Acknowledgements**

The Defense Threat Reduction Agency, Clinical Research Management, Inc and the National Research Council have provided financial and/or programmatic support. The technical assistance of Andy Zheng, Michael Addis, Keenan Bailey and Soma Chanda is gratefully acknowledged.

### **8. References**

214 Modern Telemetry

The use of telemetry to record biopotentials like the EEG during long periods is fundamental to study the role of brain damage in epileptogenesis. Our group (de Araujo Furtado *et al*., 2010) found and quantified SRS in rats exposed to the nerve agent soman, several days postexposure. White and co-workers (2010) investigated the occurrence of spontaneous seizures in the kainate model through the use of a commercially available telemetry system (DSI). They were able to identify spikes and spike clusters, which occurred after the initial, prolonged seizure, but preceded the first spontaneous seizure, thus finding clues about the development of chronic epilepsy using the EEG as a powerful biomarker. An EEG telemetry system can allow the investigation of a phenomenon that without continuous monitoring would never be accurately studied. Still, one must be careful about the interpretation of results because the

The identification and characterization of SRS, that occur after acute seizures induced by soman, emphasize the importance of quantifying SRS in studies where the objective is to find new therapeutics against soman-provoked seizures. It is known that exposure to soman can cause acute and chronic damage (Petras, 1994; Shih *et al*., 2003), therefore, an ideal evaluation model must assess the neuroprotective effect of the therapeutic agent with both short-term and long-term EEG monitoring. However, it is very common to monitor the EEG for a time period of only 1–2 days post-exposure in the field of nerve agent studies. Obviously, this period is not enough to detect SRS and long-term morphological changes. Optimally, one should study the EEG changes over a period of several months (limited by

Among the limitations of telemetry, battery life is probably one of the most important. Also, an implantable telemetry system must be miniaturized in a way that the subject is not disturbed. Sealing of the transmitter plays a role, because if sealing is compromised it can ruin the device and consequentially the experiment. Several new technologies may address these limitations. New approaches that allow battery integration with the circuit/electrodes and the use of rechargeable batteries may be a great advantage (Budgett *et al*., 2007). The lack of spatial resolution that is inherent in the EEG could be compensated by the use of arrays of multiple electrodes and the use of Bluetooth technology. Rechargeable batteries could permit one to run very long-term experiments (perhaps 1-2 years), studying epileptogenesis not only in animals that display acute seizures, but also on those that do not exhibit initial status epilepticus. Finally, the use of a semi-automated algorithm is a minimum requirement for data analysis in order to analyze continuous long-term EEG

Material has been reviewed by the Walter Reed Army Institute of Research. There is no objection to its presentation and or publication. The opinions or assertions contained herein are the private views of the author, and are not to be construed as official or as reflecting

The Defense Threat Reduction Agency, Clinical Research Management, Inc and the National Research Council have provided financial and/or programmatic support. The technical

number of EEG channels limits the identification of the epileptic focus.

**5. Conclusions** 

the battery life of telemetry devices).

recordings in a time-efficient and accurate manner.

true views of the Department of the Army or Department of Defense.

**6. Disclosure statement** 

**7. Acknowledgements** 


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**11** 

*France* 

**An Efficient Adaptive** 

*2CEA LETI MINATEC,* 

Christophe Delavaud2 and Pascal Ciais2 *1Institut Supérieur d'Electronique de Paris,* 

**Antenna-Impedance Tuning Unit** 

**Designed for Wireless Pacemaker Telemetry** 

Since its first implantation into human body in 1958, pacemaker has known several evolutions [1-2] to become nowadays a vital cardiovascular device frequently prescribed to improve the quality of life for hearth failure patients. To increase the quality of service, pacemaker industry tends to integrate wireless telemetry technology into the medical device to allow home monitoring of the patient. Home monitoring technology challenges to analyse

The pacemaker radio communication module, designed to exchange data with an external base station, features new technologies including, but not limited, new architecture, low power design technique, acoustic wave filter co-integration, miniaturized antenna design, etc. The miniaturized antenna embedded on the pacemaker device is typically a narrow bandwidth high-Q antenna [3] easily detuned by unpredictable near field environmental factors [4-6]. The input impedance of the implanted antenna can vary due to the tissue (muscle, fat, skin, etc.) properties, thickness, and also the individual properties which differ from one person to another. In addition, the patient position and more generally the nearby objects may cause also change in the antenna input impedance. Mismatch of the antenna impedance significantly degrades the transmitter radiated output power, the receiver

To highlight the possible random variability in the antenna input impedance that contributes to generate more or less important mismatch losses, precise characterization of the pacemaker antenna using different realistic human models is needed. In this way, electromagnetic simulations and measurements of the input impedance of the antenna

To guarantee the success of the wireless communication even in the presence of mismatch losses, traditional solution over specifies the design of the RF power modules consuming more energy at the expense of the battery lifetime. This solution is obviously not mandatory where a targeting lifetime at least greater than seven years is required for such implantable medical device. More suitable solution is focused on the addition of an adaptive antennaimpedance tuning unit to automatically match the antenna input impedance to the optimal

and to diagnose while the patient is sitting or sleeping at home.

sensitivity, and therefore the power efficiency of the radio transceiver.

impedance of the RF front-end radio communication module.

immersed into homogeneous and heterogeneous human model were performed.

**1. Introduction** 

Francis Chan Wai Po1, Emeric de Foucauld2, Jean-Baptiste David2,

