RF waves, SAR measurement and future wireless µsensors.

International audienceHumans are permanently exposed to multiple electromagnetic (EM) fields, potentially dangerous, which represent a true public health concern. The basic restrictions impose that the absorbed power per unit mass (Specific Absorption Rate, SAR) shall not exceed 0.08 W/Kg for the whole body and 2W/Kg locally for 10 g of tissue (E.C. recommendation, July 12th 1999). The measurements of the SAR induced by GSM and UMTS systems still follow protocols using current standards and measurement tools based on technologies and concepts dating back before 2000. The objective of our project is to study a method using multiphysic solutions allowing SAR measurement with miniature probes and the transmission of measured data. One of the applications of our project consists in the design and realization an incubator to cultivate neural cells and tissues, containing an antenna to produce an EM field and specific sensors (µcoils of about 100µm) for the “near field” measures of SAR and µthermocouples for temperature control; we expect to observe mainly “non-thermal” effects of EM fields. This approach is considered as a “high priority research need” in the conclusions of the WHO (2006). The frequency was chosen in the range of GSM (1.8GHz), but this system will be adaptable for other wave lengths and able to closely follow the evolution of new communication technologies. Further studies will focus on measures using microsensors “self operated” (the EM field will be used as a source of energy for the sensor which could be directly interrogated). There are many practical applications in vivo in diagnosis and real-time biological and clinical measures