CEA-Leti’s antenna laboratory has developed DEVIN, a miniaturized personal exposimeter designed to continuously measure, in real-world conditions, both the power emitted by a smartphone and its distance from the body. Commissioned by ANSES, the French Agency for Food, Environmental and Occupational Health & Safety, the device was created to give WHO epidemiologists reliable data on actual phone exposure, filling a long-standing gap between laboratory studies and epidemiological surveys based largely on self-reported questionnaires.

DEVIN is an “uplink” exposimeter, meaning it measures the signal transmitted by the mobile phone itself rather than emissions from base stations. That distinction matters because a handset can transmit up to 200 milliwatts, far less than a cell tower, but often at extremely close range to the body — against the ear, in a pocket, or near the brain. CEA-Leti’s technical achievement was to integrate a complete measurement system into a device the size of a credit card and only 1 centimeter thick, allowing it to be attached to the back of a phone.

The instrument records 10 measurements per second, including transmitted power, frequency band, and the position of the phone’s transmitting antenna relative to the body. That makes it possible to estimate how energy is distributed inside the body and to compare exposure across different usage patterns. Tests on 300 volunteers showed substantial variation: holding a phone to the ear during a call produces higher exposure than sending a text message, and exposure rises when the handset is farther from the base station because the phone increases its power to maintain the network link. Even so, all measured values remained well below regulatory limits.

The work was extended through the European Seawave project, led by the University of Thessaloniki with CEA-Leti among the partners, which produced a 5G-compatible version of DEVIN. This newer model can detect the different antennas used in recent smartphones and runs for several days on battery power. Because it measures physical quantities directly, it does not depend on mobile operators or on any specific phone model, and it avoids relying on telecom signals that change from one generation of mobile technology to the next.

The project has already resulted in several scientific publications, including studies on the determinants of radiofrequency electromagnetic fields emitted by smartphones in French cellular networks and validation work for DEVIN5G. More broadly, it gives epidemiologists a tool that can keep pace with the rapid rollout of mobile networks, while underscoring CEA-Leti’s ability to develop advanced instrumentation in response to public-health needs.

​​​​​​​​​​​The CEA-Leti antenna laboratory has developed DEVIN, a miniaturized personal exposimeter capable of continuously measuring, under real-life conditions, the power emitted by a smartphone as well as its distance from the body. Designed at the request of ANSES to provide reliable data to WHO epidemiologists, this instrument, already tested on 300 volunteers and subsequently adapted to 5G as part of the Seawave project, showcases CEA-Leti's expertise in miniaturization and instrumentation in support of public health research.​

Until now, studies on the impact of electromagnetic waves from mobile phones have relied on laboratory experiments based on a worst-case scenario. Epidemiological studies, meanwhile, have been based on self-reported questionnaires, without any objective measurement of actual exposure.

To address this gap, ANSES (the French Agency for Food, Environmental and Occupational Health & Safety) commissioned CEA-Leti to design a measurement instrument. The objective? To provide WHO epidemiologists with reliable data on people's actual exposure when using their phones.

This is known as an “uplink" exposimeter, as it specifically measures the signal emitted by the mobile phone. The phone can transmit up to 200 milliwatts of power, much less than base station antennas. The difference is that it is used very close to the body, either in contact with the skin or close to the brain.

CEA-Leti's innovation lies in integrating a complete system into a miniaturized device. DEVIN was reduced to the size of a credit card, with a thickness of just one centimeter, so that it can be attached to the back of a phone.

It records ten measurements per second, including transmitted power, frequency band, and the position of the transmitting antenna relative to the body, making it possible to determine how energy is distributed within the body.

The results revealed significant variations in exposure levels. For example, a phone call with the handset held against the ear results in greater exposure than sending a text message, while greater distance from a base station increases uplink exposure.

The weaker the radio link between the transmitter and receiver, the more power the phone uses to maintain its connection to the network. However, all measurements remained well below the regulatory exposure limits.

The European Seawave project, led by the University of Thessaloniki and involving several partners, including CEA-Leti, has taken this work a step further with the development of a 5G-compatible version of DEVIN.

This version can detect different antennas integrated into recent smartphones and has a battery life of several days.

The exposimeter does not depend on mobile network operators or specific phone models. It directly measures physical quantities, without relying on telecommunications signals, which differ from one mobile technology generation to another.

This research has led to the publication of several scientific papers and provides epidemiologists with a tool to catch up with the rapid deployment of mobile networks, thanks to an instrument adapted to 5G mobile communications.

Above all, beyond the technical achievement, this research demonstrates CEA-Leti's ability to develop technology in response to societal needs.

Determinants of radiofrequency electromagnetic fields emitted by smartphones in French cellular telephony networks - ScienceDirect

Up-Link Personnal Exposimeter DEVIN5G: RF Performance Validation | IEEE Conference Publication | IEEE Xplore