Impact of low intensity millimetre waves on cell functions

Investigations on the biological impact of low levels of millimetrewave energy date back to the first experiments on the generation and detection of these high-frequency signals by Sir Jagadis Chunder Bose at the end of the 19th century. Slightly more than a hundred years later, millimetre-wave transmission has become a ubiquitous commercial reality. Despite the widespread use of millimetre-wave transmitters for communications, radar and even non-lethal weapons systems, only a handful of researchers have funded programmes focusing on millimetre-wave interactions with biological systems. As such, there is a growing need for a better understanding of the mechanisms of these interactions and their possible adverse and therapeutic implications. Independent of the health impact of long-term exposure to high doses of millimetre-wave energy on whole organisms, there exists the potential for subtle effects on specific tissues or organs which can best be quantified in studies which examine real-time changes in cellular function as energy is applied. In this Letter, a series of experiments are presented which show changes in cell membrane potential and the action potential firing rate of cortical neurons under short (1 min) exposures to continuous-wave 60 GHz radiation at mW/cm power levels, more than 1000 times below the US government maximum permissible exposure. The findings have implications for non-contact stimulation and control of neurologic function, and might prove useful in a variety of health applications from suppression of peripheral neuropathic pain to the treatment of central neurological disorders.