UC San Diego

There has long been speculation of inter-cellular communication through weak electromagnetic (EM) fields playing a functional role in biological systems. The predominant theory for how a cell could ever generate electric fields is mechanical vibration of charged or polar biomolecules such as cell membranes or microtubules. The challenge to this theory is explaining how high-frequency vibrations would not be over-damped by surrounding biological media. As many of these suspected resonators are too large for atomistic molecular dynamics simulations, accurately modeling biological resonators remains an ongoing challenge. Starting with energy transfer expressions from coupled-mode theory, we derive expressions for the minimum quality factor required to sustain communication for both near- and far-field interactions. Next, we analyze microtubules as candidate ``antennas", using a custom electromagnetic simulation technique to assess the field strength from vibrating microtubules. Building off the difficulties of simulating the microtubule in conventional molecular simulation techniques, we develop our own method of simulating electrodynamic interactions in biological systems and implement it for a model of linear DNA. Lastly, we discuss experimental work with our collaborators in the biological sciences. We developed a series of band pass filter frequency selective surfaces to narrow down the frequency of signaling in barrier experiments, then followed up with listening and stimulation type experiments in the biologically active frequency spectrum. Overall, our modeling suggests that any potential biological EM signaling could not overcome the damping from surrounding viscous media, at least based on identified biological resonances. Biological resonators contain insufficient charge or dipole moments to produce significant fields to overcome background thermal energy. Electrodynamic interactions seem to require electric fields or velocities unrealistic in biological systems. Our experimental results are mixed in their findings, giving indirect evidence of biological signaling, but providing no direct measurement of EM signals.